Troubleshoot your Mitsubishi MELSERVO MR-J4 Servo Amplifier with our guide. Decode “AL.” alarm codes, fix absolute position errors (AL.25), and use MR Configurator2 for advanced diagnostics.

MR-J4 Fault Codes Reference Table

Below is the comprehensive list of alarm and warning codes for the MR-J4 servo amplifier:

Mitsubishi MELSERVO MR-J4 Fault Codes List

tr>

Fault Code and Meaning	Cause and Remedy
AL. 10.1 Undervoltage (Voltage drop in the control circuit power)	Cause: (1) Control circuit power supply connection is incorrect. (2) Voltage of control circuit power supply is low. (3) Power was cycled before internal power stopped. (4) Instantaneous power failure occurred. (5) Distorted voltage due to power regeneration converter. Remedy: Check the connection of the control circuit power supply. Connect it correctly. Review the voltage (200V class: >160VAC, 400V class: >280VAC, 24VDC: >17VDC). Cycle the power after the seven-segment LED of the servo amplifier is turned off. Review the power supply capacity and stability. Review the setting of "[AL. 10 Undervoltage] detection method selection" (Pr. PC27 / Pr. PC20).
AL. 10.2 Undervoltage (Voltage drop in the main circuit power)	Cause: (1) Main circuit power supply wiring disconnected. (2) Wiring between P3/P4 or P1/P2 disconnected. (3) Magnetic contactor control connector disconnected. (4) Bus bar between converter and drive unit disconnected. (5) Main circuit power supply voltage is low. (6) Alarm occurred during acceleration (bus voltage drop). (7) Servo amplifier malfunctioning. (8) Converter unit malfunctioning. Remedy: Check wiring and connect correctly. Increase the voltage of the main circuit power supply. Increase the acceleration time constant or increase power supply capacity. Replace the servo amplifier. Replace the converter unit.
AL. 11.1 Switch setting error (Axis number setting error)	Cause: (1) The setting of the axis No. is incorrect. (2) The station number is set to a value other than "1" to "120". Remedy: Check settings of auxiliary axis number switches (SW2-5/SW2-6) and axis selection rotary switch (SW1). Set correctly. Set the station number correctly (SW2/SW3). If settings are correct, replace the servo amplifier.
AL. 11.2 Switch setting error (Disabling control axis setting error)	Cause: The setting of the disabling control axis switch is incorrect. Remedy: Check if setting matches valid configurations (e.g., Only A-axis disabled, Only B-axis disabled, etc.). Set the switch correctly. If correct, replace the servo amplifier.
AL. 12.1 Memory error 1 (RAM) (RAM error 1)	Cause: (1) A part in the servo amplifier (RAM) has failed. (2) Noise from nearby device caused the error. Remedy: Disconnect cables except control circuit power and check repeatability. If repeatable: Replace the servo amplifier. If not repeatable: Check power supply for noise and take countermeasures against surroundings.
AL. 12.2 to 12.6 Memory error 1 (RAM) (RAM error 2 - 6)	Cause: See AL. 12.1. Remedy: Check with the method for [AL. 12.1].
AL. 13.1 Clock error (Clock error 1)	Cause: (1) MR-J3-T10 came off during CC-Link IE communication. (2) A part in the servo amplifier is failure. (3) Clock error transmitted from controller. (4) Servo amplifier of the next axis is malfunctioning. (5) Noise or shorted connector. Remedy: Check if [AL. 74 Option card error 1] occurred. Follow methods for AL. 74. Disconnect cables (except control power). If repeatable, replace servo amplifier. Replace the controller. Replace the servo amplifier of the next axis. Take countermeasures against noise/short circuits.
AL. 14.1 Control process error (Control process error 1)	Cause: (1) MR-J3-T10 came off during CC-Link IE communication. (2) Parameter setting is incorrect. (3) Noise or shorted connector. (4) Servo amplifier malfunctioning. Remedy: Check if [AL. 74] occurred. Follow AL. 74 instructions. Set parameters correctly. Check power supply for noise; check if connector is shorted. Replace the servo amplifier.
AL. 14.2 Control process error (Control process error 2)	Cause: (1) CC-Link IE communication drop. (2) Synchronous signal error from controller. (3) Adaptive tuning/Vibration suppression executed for multiple axes simultaneously. (4) Parameter setting incorrect. Remedy: Check AL. 74 history. Replace the controller. Execute tuning for each axis individually. Set parameters correctly. Replace the servo amplifier.
AL. 15.1 Memory error 2 (EEP-ROM) (EEP-ROM error at power on)	Cause: (1) EEP-ROM malfunctioning. (2) Noise caused the error. (3) Write times exceeded 100,000 (parameters/programs changed too frequently). Remedy: Disconnect cables. If repeatable, replace servo amplifier. Take countermeasures against noise. Replace servo amplifier. Change process to use parameters/point tables less frequently.
AL. 15.4 Memory error 2 (EEP-ROM) (Home position information read error)	Cause: (1) EEP-ROM malfunctioning. (2) Multiple rotation data saved as home position read failure. (3) Noise. (4) Write times exceeded 100,000. Remedy: Replace servo amplifier if repeatable. Make home position setting again. Take countermeasures against noise. Replace servo amplifier and reduce parameter write frequency.
AL. 16.1 Encoder initial communication error 1 (Receive data error 1)	Cause: (1) Encoder cable malfunctioning (disconnected/shorted). (2) Linear servo motor/encoder not compatible. (3) Wiring of linear encoder incorrect. (4) Servo amplifier malfunctioning. (5) Encoder malfunctioning. Remedy: Replace or repair the encoder cable. Use a compatible servo amplifier/linear encoder. Wire the linear encoder correctly (Check PSEL). Replace the servo amplifier. Replace the servo motor or linear encoder.
AL. 16.3 Encoder initial communication error 1 (Receive data error 3)	Cause: (1) An axis not used is not set as disabled-axis. (2) Encoder cable disconnected. (3) Communication method parameter incorrect [Pr. PC22/PC04]. (4) Parallel drive system parameter [Pr. PF40] incorrect. (5) Encoder cable malfunctioning. Remedy: Set unused axis as disabled-axis (SW2). Connect encoder cable correctly. Set parameters correctly. Replace or repair the cable. Review power and related parts for instantaneous failure. Replace servo amplifier or encoder.
AL. 16.8 Encoder initial communication error 1 (Incompatible encoder)	Cause: (1) Incompatible servo motor or linear encoder connected. (2) Software version of servo amplifier does not support the motor/encoder. (3) Encoder is malfunctioning. Remedy: Replace with a compatible motor/encoder. Replace servo amplifier with one that supports the motor/encoder. Replace the servo motor or linear encoder.
AL. 17.1 Board error (Board error 1)	Cause: (1) A current detection circuit is malfunctioning. (2) Noise caused the device error. Remedy: If it occurs during servo-on, replace the servo amplifier. Take countermeasures against noise.
AL. 17.3 to 17.9 Board error (Board error 2 - 8)	Cause: Servo amplifier recognition signal, axis setting switch, or internal components (inrush suppressor) malfunctioning. Remedy: Disconnect cables. If repeatable, replace the servo amplifier. Take countermeasures against noise in the surrounding environment.
AL. 19.1 Memory error 3 (Flash-ROM) (Flash-ROM error 1)	Cause: (1) The Flash-ROM is malfunctioning. (2) Noise caused the device error. Remedy: Disconnect cables. If repeatable, replace the servo amplifier. Take countermeasures against noise.
1A.1 Servo motor combination error 1	Cause: The combination of servo amplifier and servo motor is incorrect, settings are invalid, or an encoder is malfunctioning. Remedy: Check the model name of the servo motor and corresponding servo amplifier; use the correct combination. Check and correct the setting of [Pr. PA01] (Rotary/Linear/Direct drive selection). For linear motors: Check if [Pr. PA17] and [Pr. PA18] are set correctly. Check if the servo amplifier software version supports the connected motor (e.g., TM-RG2M/TM-RU2M). Replace the servo motor and check repeatability.
1A.2 Servo motor control mode combination error	Cause: The setting of [Pr. PA01] does not correspond to the connected servo motor, or encoders are connected reversely in fully closed loop mode. Remedy: Set [Pr. PA01] correctly. Check the connection destination of the encoder and connect it correctly.
1A.4 Servo motor combination error 2	Cause: The servo amplifier is malfunctioning. Remedy: Replace the servo amplifier.
1B.1 Converter unit error	Cause: The protection coordination cable is not correctly connected, or an alarm occurred in the converter unit. Remedy: Check the protection coordination cable connection and connect it correctly. Check the alarm of the converter unit and take action following the converter unit remedies.
1E.1 Encoder malfunction	Cause: An encoder is malfunctioning or environmental noise/vibration is interfering. Remedy: Replace the servo motor and check repeatability. Check for noise, ambient temperature, and vibration; take countermeasures against the cause.
1E.2 Load-side encoder malfunction	Cause: A load-side encoder is malfunctioning or environmental noise is interfering. Remedy: Replace the load-side encoder and check repeatability. Check for noise, ambient temperature, and vibration; take countermeasures against the cause.
1F.1 Incompatible encoder	Cause: Connected motor/encoder is not compatible, software version is too old, or encoder is malfunctioning. Remedy: Replace the motor/encoder with a compatible one. Replace the servo amplifier with one whose software version supports the encoder. Replace the servo motor or linear encoder. If issue persists, replace the servo amplifier.
1F.2 Incompatible load-side encoder	Cause: Connected load-side encoder is incompatible, software version is too old, or encoder is malfunctioning. Remedy: Use a load-side encoder compatible with the servo amplifier. Replace the servo amplifier with one whose software version supports the load-side encoder. Replace the load-side encoder. If issue persists, replace the servo amplifier.
20.1 Encoder normal communication - Receive data error 1	Cause: Encoder cable failure, grounding issue, incorrect parameters, or hardware malfunction. Remedy: Check if encoder cable is disconnected or shorted; repair or replace cable. Connect the external conductor of the encoder cable to the connector ground plate. Check and correct communication method parameters ([Pr. PC22], [Pr. PC04], etc.). In parallel drive systems, check/correct [Pr. PF40]. Replace the servo amplifier. Replace the servo motor or linear encoder. Check for noise/environment issues and take countermeasures.
20.2 Encoder normal communication - Receive data error 2	Cause: Same causes as Fault 20.1. Remedy: Refer to the check methods and remedies for [AL. 20.1].
20.5 Encoder normal communication - Transmission data error 1	Cause: A/B/Z-phase wiring incorrect, cable malfunction, or grounding issue. Remedy: Check A/B-phase pulse signals (PA, PAR, PB, PBR); repair encoder cable. Check grounding of the encoder cable shield. If using linear encoder, check parameter settings. If unresolved, replace servo amplifier or encoder.
20.6 Encoder normal communication - Transmission data error 2	Cause: Z-phase wiring incorrect, cable malfunction, or grounding issue. Remedy: Check Z-phase pulse signals (PZ/PZR); repair encoder cable. Refer to remedies for [AL. 20.1] for cable/grounding checks.
21.1 Encoder data error 1	Cause: High speed/acceleration oscillation, grounding issue, encoder malfunction, or noise. Remedy: Decrease the loop gain and check repeatability. Check if encoder cable shield is connected to the ground plate. Replace the servo motor. Take countermeasures against noise/vibration.
21.2 Encoder data update error	Cause: Encoder malfunction, grounding issue, or noise. Remedy: Replace the servo motor. Check encoder cable grounding. Take countermeasures against noise/ambient temperature.
21.4 Encoder non-signal error	Cause: Encoder signal not input, grounding issue, or noise. Remedy: Review the wiring; check if the encoder cable is connected correctly. Check encoder cable grounding. Take countermeasures against noise/environment.
24.1 Ground fault detected by hardware detection circuit	Cause: Servo amplifier malfunction, ground fault in motor power cable, ground fault in motor, or main circuit short. Remedy: Disconnect servo motor power cables (U/V/W); if alarm persists, replace servo amplifier. Check if motor power cable is shorted; replace if necessary. Check insulation of the motor (between U/V/W and Ground); replace motor if shorted. Check for shorts in the main circuit power supply cable; correct wiring. Check regenerative resistor wiring. Take countermeasures against noise.
24.2 Ground fault detected by software detection function	Cause: Control circuit power supply voltage low (under 20V) on specific models, or ground faults (similar to 24.1). Remedy: Ensure control circuit power supply voltage is 20 V or higher before inputting servo-on. Disconnect motor cables; if alarm persists, replace servo amplifier. Check for cable shorts or motor insulation failure. Correct main circuit wiring.
25.1 Servo motor encoder - Absolute position erased	Cause: First power on, battery removed/disconnected, low battery voltage, or cable/connection issues. Remedy: If first time startup: Mount battery correctly and perform home position return. If battery was removed/disconnected: Check mounting and perform home position return. If using junction battery cable: Check connections to CN4 and battery case. If battery voltage is less than 3 V DC: Replace battery. Check if the correct/recommended encoder cable is used. Check for loose connections or cable failures (repair/replace if needed). If servo amplifier or encoder is malfunctioning, replace them.
25.2 Scale measurement encoder - Absolute position erased	Cause: First power on, battery issues, cable issues, or hardware malfunction. Remedy: Perform home position return (required on first startup or after battery loss). If battery voltage is low (< 3V DC), replace the battery. Check for loose connections or shorts in the encoder cable. Replace the servo amplifier or scale measurement encoder if not repeatable.
27.1 Initial magnetic pole detection - Abnormal termination	Cause: Moving part collision, wiring error, resolution setting mismatch, mounting direction error, or insufficient travel distance. Remedy: Move the start position of the magnetic pole detection to avoid collisions. Correct the servo motor power cable wiring. Set linear encoder resolution ([Pr. PL02/PL03]) correctly. Mount linear encoder correctly or adjust polarity parameters ([Pr. PC45] or [Pr. PC27]). Increase travel distance setting ([Pr. PL09]) if movement is too short. Review [Pr. PL17] if travel is too long or vibration occurs.
27.2 Initial magnetic pole detection - Time out error	Cause: Motor did not stop when expected, limit switch activated, or detection voltage/travel too small. Remedy: Stop the linear servo/direct drive motor externally, then enable servo-on again. Move the start position away from limit switches. Increase travel distance/voltage with [Pr. PL09] setting.
27.3 Initial magnetic pole detection - Limit switch error	Cause: Limit switches are off during detection, or direct drive motor settings are incorrect. Remedy: Check limit switches; ensure both are OFF (or ON depending on logic). If using a direct drive motor, check [Pr. PL08] setting. Set to "_ 1 _ _".
27.4 to 27.7 Initial magnetic pole detection errors	Cause: Various estimation, speed, or position deviation errors during pole detection. Remedy: Check using the check method for AL 27.1.
28.1 Linear encoder error 2 (Environment)	Cause: (1) Ambient temperature of linear encoder is out of specification. (2) Signal level of linear encoder has dropped. Remedy: Lower the ambient temperature. Contact linear encoder manufacturer. Check mounting condition of the linear encoder and correct it.
2A.1 Linear encoder error 1-1	Cause: (1) Mounting condition of head/scale is poor. (2) External conductor not connected to ground plate. (3) Noise/Vibration interference. (4) Linear encoder internal alarm. Remedy: Adjust positions of scale and head; check repeatability. Connect encoder cable ground plate correctly. Take countermeasures against noise/vibration in the surrounding area. Contact encoder manufacturer regarding internal alarm details.
2B.1 Encoder counter error 1	Cause: (1) Encoder cable disconnected or shorted. (2) External conductor not grounded. (3) Noise interference. (4) Encoder or Direct Drive motor malfunction. Remedy: Repair or replace the encoder cable. Connect cable ground correctly. Take countermeasures against noise. Replace the direct drive motor.
2B.2 Encoder counter error 2	Cause: The connection of the servo motor (U/V/W) is incorrect. Remedy: Check U/V/W wiring and connect it correctly.
30.1 Regeneration heat error	Cause: (1) Regenerative resistor setting (Pr. PA02) incorrect. (2) Resistor not connected. (3) Input power voltage is too high. (4) Regenerative load ratio exceeded 100%. Remedy: Set [Pr. PA02] correctly. Connect the regenerative resistor/option correctly. Reduce power supply voltage (e.g., check if 24V DC is set but 48V is applied). Reduce positioning frequency or load. Use a larger capacity regenerative option. If problem persists, replace servo amplifier.
30.2 Regeneration signal error	Cause: Detection circuit of the servo amplifier is malfunctioning. Remedy: Replace the servo amplifier.
30.3 Regeneration feedback signal error	Cause: Detection circuit malfunction or noise. Remedy: Remove regenerative option, check if alarm occurs at power on. If yes, replace amplifier. Check for noise or ground faults in the environment.
31.1 Abnormal motor speed (Overspeed)	Cause: (1) Command pulse frequency too high. (2) Electronic gear settings incorrect. (3) Servo system unstable/oscillating. (4) Input voltage drop or wiring issue. (5) Encoder cable connection issue. Remedy: Check command pulse frequency and operation pattern. Review electronic gear ratio settings. Adjust servo gain to stop oscillation. Check 24V DC / Main circuit power supply voltage stability. Check encoder cable connection (CN2A/CN2B/CN2C). Replace servo motor or encoder if hardware failure.
32.1 Overcurrent (Hardware detected)	Cause: (1) Servo amplifier malfunction. (2) Ground fault or short circuit in motor cable. (3) Servo motor insulation failure. (4) Dynamic brake malfunction. (5) Wiring of regenerative resistor incorrect. Remedy: Disconnect motor cables; if alarm persists, replace amplifier. Check motor cables for shorts/ground faults; replace if necessary. Check motor insulation. Wire the regenerative resistor correctly. Check for noise in the environment.
32.2 Overcurrent (Software detected)	Cause: (1) Servo gain is too high (oscillation). (2) Servo amplifier or motor malfunction. (3) Ground fault/short in cable. (4) Encoder cable connection incorrect. Remedy: Reduce speed loop gain ([Pr. PB09]). Check for oscillation and suppress it. Check motor and encoder wiring connections. Replace servo amplifier or motor if hardware is faulty.
33.1 Main circuit voltage error (Overvoltage)	Cause: (1) Regenerative resistor setting incorrect. (2) Wire breakage of built-in/option resistor. (3) Regeneration capacity insufficient. (4) Power supply voltage too high. Remedy: Check and correct [Pr. PA02] setting. Measure resistance of built-in/option resistor; replace if open. Use a larger capacity regenerative option or reduce load/deceleration speed. Reduce the power supply voltage to prescribed value.
34.1 SSCNET receive error 1	Cause: (1) SSCNET cable disconnected, dirty, or broken. (2) Controller or Amp hardware failure. (3) Noise interference. Remedy: Connect SSCNET cable correctly. Wipe dirt from cable tip. Replace SSCNET cable. Take noise countermeasures. Replace servo amplifier or controller if hardware failure.
35.1 Command frequency error	Cause: (1) Input pulse frequency is too high. (2) Command input pulse filter setting incorrect. (3) Noise interference. Remedy: Reduce command pulse frequency. Review [Pr. PA13] filter setting. Take countermeasures against noise.
36.1 SSCNET receive error 2	Cause: Intermittent communication error (similar causes to AL 34.1 but specific timing/interval). Remedy: Check cable connections and cleanliness. Replace SSCNET cable. Take noise countermeasures. Replace servo amplifier or controller.
37.1 Parameter setting range error	Cause: (1) A parameter was set out of setting range. (2) A parameter setting contradicts another. Remedy: Check the parameter error No. and setting value. Set the value within the correct range. Correct the contradictory setting values. Replace the servo amplifier if the error persists.
37.2 Parameter combination error	Cause: (1) A parameter setting contradicts another. (2) [Pr. PA01] master/slave settings are incorrect. (3) Forced stop deceleration function enabled in [Pr. PA04]. Remedy: Correct the setting value (check master-slave settings if applicable). Set [Pr. PA01] to "standard control mode" or "fully closed loop control mode". Disable "forced stop deceleration function selection" in [Pr. PA04].
37.3 Point table setting error	Cause: (1) The setting of point tables is incorrect. (2) Point table setting changed due to servo amplifier malfunction. Remedy: Check if point table settings are within range using MR Configurator2. Correct the setting value. Replace the servo amplifier.
39.1 Program error	Cause: (1) A checksum of the program did not match at power-on. (2) Program changed due to malfunction. Remedy: Rewrite the program. Replace the servo amplifier.
39.2 Instruction argument external error	Cause: (1) Program never written since initialization. (2) Command argument is out of specifications. Remedy: Write the program. Correct the command description. Replace the servo amplifier.
39.3 Register No. error	Cause: A specified number of the general purpose register used for a command is out of specifications. Remedy: Correct the command description. Replace the servo amplifier.
39.4 Non-correspondence instruction error	Cause: A used command corresponds to a non-existent program. Remedy: Correct the command description. Replace the servo amplifier.
3A.1 Inrush current suppression circuit error	Cause: Inrush current suppressor circuit is malfunctioning. Remedy: Replace the servo amplifier.
3D.1 Parameter error for driver communication (Slave)	Cause: The master transmit data selection for driver communication is not set correctly. Remedy: Check settings of [Pr. PD16] and [Pr. PD17] on the master side. Set the parameters correctly.
3D.2 Parameter error for driver communication (Master)	Cause: Issue with master communication settings. Remedy: Check with the check method for [AL. 3D.1].
3E.1 Operation mode error	Cause: (1) MR-J4 connection changed (compatibility mode/SSCNET controller issues). (2) [Pr. PA01] setting value was changed. Remedy: Restore servo amplifier to factory setting using MR Configurator2 ("MR-J4(W)-B mode selection"). Reconnect the servo amplifier to the controller. Set [Pr. PA01] correctly.
3E.6 Operation mode switch error	Cause: Positioning data memorized in amplifier differs from actual positioning mode. Remedy: After changing positioning mode, initialize the point table/program method. Refer to section 7.2.8 [Pr. PT34] of the Instruction Manual. Set the positioning mode back to the correct setting.
3E.8 MR-D30 combination error	Cause: MR-D30 functional safety unit connected while CC-Link IE Field Network Basic communication is selected. Remedy: Disconnect the MR-D30 unit.
42.1 Servo control error (Position deviation)	Cause: (1) [Pr. PA17] and [Pr. PA18] not set for linear motor used. (2) Linear encoder resolution setting differs. (3) Incorrect mounting direction of linear encoder. (4) Servo motor wiring incorrect. (5) Initial magnetic pole detection not executed. Remedy: Set [Pr. PA17] and [Pr. PA18] correctly. Correct [Pr. PL02] and [Pr. PL03]. Mount encoder correctly or review "encoder pulse count polarity selection" ([Pr. PC45] / [Pr. PC27]). Connect wiring correctly. Execute magnetic pole detection.
42.2 Servo control error (Speed deviation)	Cause: (1) [Pr. PA17/PA18] settings incorrect. (2) Linear encoder resolution setting incorrect. (3) Incorrect mounting direction. (4) Wiring incorrect. (5) Magnetic pole detection not executed. (6) Speed deviation exceeded detection level. Remedy: Set parameters correctly (PA17, PA18, PL02, PL03). Review encoder mounting and polarity parameters. Review operation status and [Pr. PL06] setting.
42.3 Servo control error (Torque/Thrust deviation)	Cause: (1) [Pr. PA17/PA18] settings incorrect. (2) Linear encoder resolution settings incorrect. (3) Incorrect mounting direction. (4) Wiring incorrect. (5) Magnetic pole detection not executed. (6) Torque/thrust deviation exceeded detection level. Remedy: Set parameters correctly. Review operation status and [Pr. PL07] setting.
42.8 Fully closed loop control error (Position deviation)	Cause: (1) Load-side encoder resolution setting incorrect. (2) Mounting direction of load-side encoder incorrect. (3) Position deviation exceeded detection level. Remedy: Set [Pr. PE04] and [Pr. PE05] correctly. Review encoder mounting and polarity selection ([Pr. PC45] / [Pr. PC27]). Review operation status and [Pr. PE07].
42.9 Fully closed loop control error (Speed deviation)	Cause: (1) Load-side encoder resolution setting incorrect. (2) Mounting direction incorrect. (3) Speed deviation exceeded detection level. Remedy: Set [Pr. PE04] and [Pr. PE05] correctly. Review encoder mounting and polarity. Review operation status and [Pr. PE06].
42.A Fully closed loop control error (Command stop)	Cause: Position deviation during command stop. Remedy: Check with the check method for [AL. 42.8].
45.1 Main circuit device overheat error 1	Cause: (1) Ambient temperature exceeded 55°C. (2) Close mounting out of specifications. (3) Overload status repeated. (4) Cooling fan/heat sink clogged. (5) Servo amplifier malfunction. Remedy: Lower the ambient temperature. Use within mounting specifications. Check operation pattern. Clean the cooling fan/heat sink periodically. Replace the servo amplifier.
45.2 Main circuit device overheat error 2	Cause: Same as 45.1. Remedy: Check with the check method for [AL. 45.1].
46.1 Abnormal temperature of servo motor 1	Cause: (1) Ambient temperature of servo motor exceeded prescribed value. (2) Servo motor is overloaded. (3) Thermal sensor in encoder is malfunctioning. Remedy: Lower the ambient temperature. Reduce load or review operation pattern. Replace the servo motor.
46.2 Abnormal temperature of servo motor 2	Cause: (1) Ambient temperature exceeded value (linear/direct drive). (2) Motor overloaded. (3) Thermistor wire shorted. Remedy: Lower the ambient temperature. Reduce load or review operation pattern. Repair cable or replace servo motor.
46.3 Thermistor disconnected error	Cause: (1) Parallel drive parameters/axis number incorrect. (2) Parallel drive encoder cable not connected. (3) Thermistor wire not connected. (4) Incorrect encoder cable model used. Remedy: Set [Pr. PF37] and axis number (SW2-3/4, SW1) correctly. Connect the encoder cable correctly. Change cable to MR-ENECBL_M-H-MTH if necessary. Repair lead wire or replace servo motor.
46.4 Thermistor circuit error	Cause: Thermistor circuit of the servo amplifier is malfunctioning. Remedy: Replace the servo amplifier.
46.5 Abnormal temperature of servo motor 3	Cause: See 46.1. Remedy: Check with the check method for [AL. 46.1].
46.6 Abnormal temperature of servo motor 4	Cause: Current applied in excess of continuous output current. Remedy: Reduce the load or review operation pattern. Use a larger capacity motor.
47.1 Cooling fan stop error	Cause: (1) Foreign matter caught in cooling fan. (2) Cooling fan life expired. Remedy: Remove foreign matter. Replace the servo amplifier.
47.2 Cooling fan speed reduction error	Cause: (1) Foreign matter caught in cooling fan. (2) Cooling fan life expired (speed dropped below alarm level). Remedy: Remove foreign matter. Replace the servo amplifier.
50.1 Thermal overload error 1	Cause: (1) Servo motor power cable disconnected. (2) U/V/W connection incorrect. (3) Electromagnetic brake not released. (4) Encoder mounting direction incorrect. (5) Continuous high current applied. (6) Encoder cable connection incorrect. (7) Servo system unstable/resonating. (8) Servo amplifier/encoder malfunction. Remedy: Repair or replace servo motor power cable. Connect U/V/W correctly. Check brake wiring and release mechanism. Review "encoder pulse count polarity selection". Reduce load or increase motor capacity. Check connections at CN2A, CN2B, CN2C. Adjust gains. Check power supply voltage (e.g., 48V vs 24V setting). Replace servo amplifier or motor.
50.2 Thermal overload error 2	Cause: See 50.1. Remedy: Check with the check method for [AL. 50.1].
50.3 Thermal overload error 4	Cause: See 50.1. Remedy: Check with the check method for [AL. 50.1].
50.4 Thermal overload error 1 during a stop	Cause: Load exceeded overload protection characteristic. Causes include: collision, power cable disconnected, hunting during servo-lock, brake not released, incorrect encoder mounting, excess current, unstable system (resonance), or amplifier/motor malfunction. Remedy: Check operation pattern (moving part collision). Repair or replace the servo motor power cable. Adjust gains if hunting occurs. Release the electromagnetic brake. Mount encoder correctly and review parameters (e.g., Pr. PC45, Pr. PC27). Reduce the load or use a larger capacity motor. Connect encoder cables (CN2A, CN2B, CN2C) correctly. Adjust gains to stop resonance. Replace the servo amplifier or servo motor.
50.5 Thermal overload error 2 during a stop	Cause: Same causes as [AL. 50.4]. Remedy: Refer to the remedies for Fault Code 50.4.
50.6 Thermal overload error 4 during a stop	Cause: Same causes as [AL. 50.4]. Remedy: Refer to the remedies for Fault Code 50.4.
51.1 Thermal overload error 3 during operation	Cause: Maximum output current flowed continuously. Causes include: power cable disconnected, incorrect U/V/W wiring, encoder cable connection, incorrect encoder mounting direction, insufficient torque (saturated), or amplifier/motor malfunction. Remedy: Repair or replace the servo motor power cable. Connect U/V/W wiring correctly. Connect encoder cable correctly. Mount encoder correctly; review "encoder pulse count polarity selection" parameters. Reduce load, review operation pattern, or use a larger capacity motor. Replace the servo amplifier. Replace the servo motor.
51.2 Thermal overload error 3 during a stop	Cause: Similar to 51.1 (collision, cable disconnects, wiring errors, saturated torque, etc.). Remedy: Check operation pattern for collisions. Refer to remedies for Fault Code 51.1 (check cables, wiring, mounting, load).
52.1 Excess droop pulse 1	Cause: Droop pulses exceeded alarm level. Causes: Disconnected power/encoder cable, incorrect wiring, torque limit enabled, collision, brake activated, voltage drop, short accel/decel time, small position loop gain, incorrect alarm level setting, or electronic gear setting. Remedy: Repair or replace servo motor power cable. Connect wiring (U/V/W) and encoder cables correctly. Increase torque limit value. Check operation pattern (collision). Release electromagnetic brake. Reduce load or use larger capacity motor. Check power supply voltage and capacity. Increase acceleration/deceleration time constant. Increase position loop gain (Pr. PB08). Set error excessive alarm level correctly (Pr. PC24, PC43, etc.). Set feedback pulse electronic gear to 1/1. Review timing of servo-on; ensure motor isn't rotated by external force.
52.3 Excess droop pulse 2	Cause: Same causes as [AL. 52.1]. Remedy: Refer to the remedies for Fault Code 52.1.
52.4 Error excessive during 0 torque limit	Cause: The torque limit has been set to 0. Remedy: Do not input a command while the torque limit value is 0.
52.5 Excess droop pulse 3	Cause: Same causes as [AL. 52.1]. Remedy: Refer to the remedies for Fault Code 52.1.
52.6 Excess droop pulse during servo-off	Cause: Servo motor shaft was rotated by external force, servo-on enabled while rotating, or controller/amp/encoder malfunction. Remedy: Review machine (prevent external force movement). Review the timing of the servo-on. Replace the controller. Replace the servo motor. Replace the servo amplifier.
54.1 Oscillation detection error	Cause: The servo system is unstable and oscillating, resonance frequency changed, or encoder malfunction. Remedy: Adjust servo gain with auto tuning. Set machine resonance suppression filter. Change the setting value of the machine resonance suppression filter. Replace the servo motor or linear encoder.
56.2 Over speed during forced stop	Cause: Forced stop deceleration time constant is short, torque limit enabled, system unstable, or encoder malfunction. Remedy: Adjust/Increase the deceleration time constant parameter (e.g., Pr. PC51). Review the torque limit value. Adjust servo gain; set machine resonance suppression filter. Replace the servo motor or linear encoder.
56.3 Estimated distance over during forced stop	Cause: Forced stop deceleration time constant is short, torque limit enabled, or encoder malfunction. Remedy: Adjust/Increase the deceleration time constant setting value. Review the torque limit value. Replace the servo motor or linear encoder.
56.4 Forced stop start error	Cause: SSCNET III cable disconnected/shorted, noise near device, amp or controller malfunction. Remedy: Connect SSCNET III cable correctly. Replace or repair the cable. Take countermeasures against noise/ambient temperature. Replace the servo amplifier. Replace the controller.
61.1 Point table setting range error	Cause: "1" or "3" was set to the sub function of the last point table (255). Remedy: Review the settings.
63.1 STO1 off	Cause: STO1 was turned off (enabled) under speed conditions (Motor speed > 50 r/min or 50 mm/s). Remedy: Turn on STO1 (disable).
63.2 STO2 off	Cause: STO2 was turned off (enabled) under speed conditions (Motor speed > 50 r/min or 50 mm/s). Remedy: Turn on STO2 (disable).
63.5 STO by functional safety unit	Cause: STO of the functional safety unit was turned off (enabled) under speed conditions. Remedy: Turn on STO (disabled).
64.1 STO input error	Cause: When a functional safety unit is used, a connector is connected to CN8 of the servo amplifier. Remedy: Turn off control circuit power, then remove the connector of CN8.
64.2 Compatibility mode setting error	Cause: J3 compatibility mode is set while functional safety unit is used (not supported). Remedy: Set the compatibility mode correctly (disable J3 mode when using functional safety unit).
64.3 Operation mode setting error	Cause: Speed monitoring function enabled in fully closed loop, direct drive, or linear servo control modes (scale measurement enabled). Remedy: Set the parameter setting correctly.
65.1 Functional safety unit communication error 1	Cause: Functional safety unit came off, unit malfunction, amp malfunction, or noise. Remedy: Turn off control circuit power and connect the functional safety unit correctly. Replace the functional safety unit. Replace the servo amplifier. Take countermeasures against noise/surroundings.
65.2 to 65.9 Functional safety unit communication errors (various)	Cause: Communication or signal between functional safety unit and servo amplifier failed. Remedy: Refer to the remedies for [AL. 65.1] (Check connection, replace unit/amp).
66.1 Encoder initial communication error - Receive data error 1	Cause: Encoder cable malfunction (disconnected/shorted), servo amplifier malfunction, encoder malfunction, or noise. Remedy: Replace or repair the encoder cable. Replace the servo amplifier. Replace the servo motor. Take countermeasures against noise/vibration.
66.2 to 66.7 Encoder initial communication errors (Data/Transmission)	Cause: Similar to 66.1. Remedy: Refer to the remedies for [AL. 66.1].
66.9 Encoder initial communication - Process error 1	Cause: Servo motor with functional safety not connected, functional safety unit malfunction, amp malfunction, encoder malfunction, or noise. Remedy: Connect a servo motor with functional safety. Replace the functional safety unit. Replace the servo amplifier. Replace the servo motor. Take countermeasures against noise.
67.1 Encoder normal communication error 1	Cause: Encoder cable malfunction, amplifier malfunction, encoder malfunction, or noise. Remedy: Repair or replace the cable. Replace the servo amplifier. Replace the servo motor. Take countermeasures against noise.
67.2 to 67.7 Encoder normal communication errors (various)	Cause: Same causes as [AL. 67.1]. Remedy: Refer to the remedies for [AL. 67.1].
68.1 Mismatched STO signal error	Cause: STO1 and STO2 not inputted correctly (wired incorrectly), input states are different, parameter setting (Pr. PF18) incorrect, circuit malfunction, or noise. Remedy: Wire STO1 and STO2 of CN8 connector correctly. Set STO1 and STO2 to the same input states. Review the parameter setting (STO diagnosis error detection time). Replace the servo amplifier. Take countermeasures against noise.
Alarm 69.1 Forward rotation-side software limit detection - Command excess error	Cause: (1) Command position exceeded 32 bits when software limit is activated. (2) Command position exceeded 30 bits from the set value. (3) Controller is malfunctioning. (4) Noise/Interference near the device. Remedy: Set the command position correctly (ensure it is within 32 bits). Set parameters [Pr. PT15] to [Pr. PT18] correctly relative to command position. Replace the controller if the error is repeatable. Check noise and ambient temperature; take countermeasures against the environment.
Alarm 69.2 Reverse rotation-side software limit detection - Command excess error	Cause: See causes for Alarm 69.1. Remedy: Follow the check method and actions for [Alarm 69.1].
Alarm 69.3 Forward rotation stroke end detection - Command excess error	Cause: (1) Command position exceeded 30 bits from detected position after LSP detection. (2) Forward rotation stroke limit switch not connected to LSP. (3) Controller malfunctioning. (4) Noise/Interference. Remedy: Check operation pattern; ensure position is set correctly. Connect the limit switch correctly. Replace the controller. Take countermeasures against noise or environmental causes.
Alarm 69.6 Lower stroke limit detection - Command excess error	Cause: (1) Command position exceeded 30 bits from detected position after RLS detection. (2) Lower stroke limit switch not wired or positioned incorrectly. (3) Noise/Interference. (4) Controller malfunctioning. Remedy: Check operation pattern and command position. Wire the limit switch correctly or adjust its position. Take countermeasures against noise. Replace the controller.
Alarm 70.1 Load-side encoder initial communication error 1 - Receive data error 1	Cause: (1) Load-side encoder cable is malfunctioning (disconnected/shorted). (2) Servo amplifier (MR-J4-_ -RJ) is not compatible with the A/B/Z-phase linear encoder used. (3) Wiring of the linear encoder is incorrect. (4) Servo amplifier malfunctioning. (5) Load-side encoder malfunctioning. (6) Noise/Interference. Remedy: Replace or repair the encoder cable. Use a servo amplifier compatible with the encoder. Wire the linear encoder correctly (Check PSEL). Replace the servo amplifier. Replace the load-side encoder. Take countermeasures against noise/environment.
Alarm 70.3 Load-side encoder initial communication error - Receive data error 3	Cause: (1) An axis not used is not set as disabled-axis. (2) Load-side encoder cable disconnected. (3) Load-side encoder cable malfunctioning. (4) Power voltage unstable (external power supply). (5) Parameter setting of communication method is incorrect. (6) Wiring of A/B/Z-phase linear encoder incorrect. (7) Servo amplifier not compatible with four-wire type linear encoder. Remedy: Set the axis as disabled-axis using control axis switches (SW2). Connect the cable correctly. Replace or repair the cable. Review power supply and related parts. Set parameters [Pr. PC44] or [Pr. PC26] correctly. Wire the encoder correctly. Use a compatible servo amplifier. Replace the servo amplifier or load-side encoder.
Alarm 70.8 Load-side encoder initial communication - Incompatible encoder	Cause: (1) A load-side encoder not compatible with the servo amplifier was connected. (2) Software version of servo amplifier does not support the load-side encoder. (3) Load-side encoder malfunctioning. Remedy: Use a load-side encoder compatible with the servo amplifier. Replace the servo amplifier with one having a supported software version. Replace the load-side encoder.
Alarm 70.A Load-side encoder initial communication - Process error 1	Cause: (1) Servo amplifier malfunctioning. (2) Load-side encoder malfunctioning. (3) Noise/Interference near device. Remedy: Replace the servo amplifier. Replace the load-side encoder. Take countermeasures against noise/vibration.
Alarm 71.1 Load-side encoder normal communication error 1 - Receive data error 1	Cause: (1) Load-side encoder cable is malfunctioning. (2) External conductor of encoder cable not connected to connector ground plate. (3) Parameter setting of communication method is incorrect. (4) Servo amplifier malfunctioning. (5) Load-side encoder malfunctioning. (6) Noise/Interference. Remedy: Repair or replace the cable. Connect the ground plate correctly. Set parameters [Pr. PC44] or [Pr. PC26] correctly. Replace the servo amplifier. Replace the load-side encoder. Take countermeasures against noise.
Alarm 72.1 Load-side encoder data error 1	Cause: (1) Encoder detected high speed/acceleration due to oscillation. (2) Load-side encoder malfunctioning. (3) Noise/Interference. Remedy: Use the encoder with low loop gain. Replace the load-side encoder. Take countermeasures against noise/vibration.
Alarm 72.4 Load-side encoder non-signal error	Cause: (1) A signal of the load-side encoder has not been inputted (wiring issue). (2) Noise/Interference. Remedy: Review the wiring; ensure cable is wired correctly. Take countermeasures against noise.
Alarm 74.1 Option card error 1	Cause: (1) MR-J3-T10 came off during CC-Link IE communication. (2) MR-J3-T10 is malfunctioning. (3) Servo amplifier is malfunctioning. Remedy: Install the option card correctly. Replace the MR-J3-T10 card. Replace the servo amplifier.
Alarm 75.3 Option card connection error	Cause: (1) MR-J3-T10 came off. (2) MR-J3-T10 is malfunctioning. (3) Servo amplifier is malfunctioning. Remedy: Install the option card correctly. Replace the MR-J3-T10 card. Replace the servo amplifier.
Alarm 79.1 Functional safety unit power voltage error	Cause: (1) Power supply of the functional safety unit is failure. (2) Functional safety unit is malfunctioning. (3) Servo amplifier is malfunctioning. (4) Noise near the device. Remedy: Install the unit correctly. Replace the functional safety unit. Replace the servo amplifier. Take countermeasures against noise.
Alarm 79.3 Abnormal temperature of functional safety unit	Cause: (1) Ambient temperature exceeded 55 °C. (2) Ambient temperature is less than 0 °C. (3) Close mounting is out of specifications. (4) An opening is clogged up. (5) Functional safety unit malfunctioning. (6) Noise/Interference. Remedy: Lower the ambient temperature. Increase the ambient temperature. Mount the unit correctly according to specifications. Clean the opening periodically. Replace the functional safety unit. Take countermeasures against noise.
Alarm 79.5 Input device error	Cause: (1) Signal of input device not inputted correctly (wiring). (2) Input device setting parameter is not set correctly. (3) Test pulse time was not set correctly. (4) Functional safety unit malfunctioning. (5) Noise/Interference. Remedy: Review the wiring. Review the parameter settings. Set the test pulse value longer or shorter as required. Replace the functional safety unit. Take countermeasures against noise.
79.6 Output device error	Cause: (1) A signal of an output device has not been outputted correctly. (2) The test pulse time was not set correctly. (3) Current of the output device is excessive. (4) The functional safety unit is malfunctioning. Remedy: Check if the output device cable is wired correctly or if the load is within specifications. Check setting of [Pr. PSD30 Output device - Test pulse off time]. Set value longer if necessary. Check if current usage is within prescribed limits. Replace the functional safety unit and check repeatability. Check for noise or ambient temperature issues in the surrounding environment.
79.7 Mismatched input signal error	Cause: (1) A mismatch of input signal DI_A and DI_B continued for a fixed time. (2) An input mismatch time was not set correctly. (3) The functional safety unit is malfunctioning. Remedy: Check if the input device cable is wired correctly. Check settings of [Pr. PSD18] to [Pr. PSD23]. Set the value longer if mismatched time is longer than set value. Replace the functional safety unit. Take countermeasures against noise or ambient environment issues.
79.8 Position feedback fixing error	Cause: (1) Position feedback data does not change within the error detection time [Pr. PSA22]. (2) The position feedback data does not change. (3) The servo motor is malfunctioning. Remedy: Review the [Pr. PSA22] parameter setting. Perform an operation which rotates the servo motor within the position feedback fixing error detection time. Replace the servo motor. Replace the functional safety unit.
7A.1 Parameter verification error (safety observation function)	Cause: (1) A parameter of the functional safety unit is incorrect. (2) The functional safety unit is malfunctioning. (3) Something near the device caused it (noise/temperature). Remedy: Review the parameter and set it correctly. Replace the functional safety unit. Take countermeasures against environmental causes.
7A.2 Parameter setting range error	Cause: (1) The initial settings for the functional safety unit have not been finished. (2) A parameter was set out of range. Remedy: Enable the setting checking the parameter contents ([Pr. PSA01]). Check the value of set parameters and set them within range.
7A.3 Parameter combination error	Cause: (1) A parameter of the functional safety unit or servo amplifier is incorrect. Remedy: Check settings: [Pr. PSA02], [Pr. PSA18]-[Pr. PSA21], [Pr. PSC03], [Pr. PSD01]-[Pr. PSD17], [Pr. PSD26], and Servo amp [Pr. PA14]. Set the parameters correctly.
7A.4 Functional safety unit combination error	Cause: (1) A combination of functional safety unit and servo amplifier is incorrect. Remedy: Return to the servo amplifier which was combined with the functional safety unit or initialize the setting.
7B.1 Encoder diagnosis error 1	Cause: (1) An encoder cable is malfunctioning (disconnected or shorted). (2) An encoder is malfunctioning. (3) The functional safety unit or servo amplifier is malfunctioning. Remedy: Repair or replace the encoder cable. Replace the servo motor. Replace the functional safety unit or servo amplifier. Check noise/vibration in the environment.
7B.2 Encoder diagnosis error 2	Cause: See causes for 7B.1. Remedy: Check it with the check method for [AL. 7B.1].
7B.4 Encoder diagnosis error 4	Cause: (1) Ambient temperature of the encoder exceeded 40 °C. (2) Ambient temperature of the encoder is less than 0 °C. (3) Servo motor is overloaded. Remedy: Lower the ambient temperature if over 40 °C. Increase the ambient temperature if under 0 °C. Reduce the load or review the operation pattern (effective load ratio). If problem persists, replace the servo motor or functional safety unit.
7C.1 Functional safety unit communication setting error	Cause: (1) Communication cycle does not match. (2) The time taken for detection of safety communication errors is not set correctly. (3) Functional safety unit malfunctioning. Remedy: Check communication cycle setting [Pr. PSC01]. Set correctly. Refer to "MR-D30 Instruction Manual" and check settings. Replace the functional safety unit.
7C.2 Functional safety unit communication data error	Cause: (1) Time taken for detection of errors is not set correctly. (2) An error occurred at the safety master station side. (3) An error occurred at the servo system controller side. Remedy: Refer to "MR-D30 Instruction Manual" and check setting. Refer to troubleshooting for the master station. Check if settings of the servo system controller side are correct.
7D.1 Stop observation error	Cause: (1) During SOS, servo motor position changed by more than SOS allowance [Pr. PSA05]. (2) During SOS, servo motor speed changed by larger than SOS allowance [Pr. PSA04]. (3) Command from controller is over the standstill speed. Remedy: Review the alarm level. Check if travel distance is larger than setting. Review parameter settings [Pr. PSA04] and [Pr. PSA15]. Check the operation pattern and commands from controller. Replace servo motor, safety unit, or servo amplifier if hardware failure is suspected.
7D.2 Speed observation error	Cause: (1) The command pulse frequency is high. (2) Settings of the electronic gear are incorrect. (3) Command from controller is excessive (over SLS speed). (4) A larger speed command than the SLS speed was inputted. (5) Servo system is unstable/oscillating. (6) Velocity waveform has overshot. Remedy: Check operation pattern and command pulse frequency. Review electronic gear settings. Review the setting value of the SLS speed. Adjust servo gain or reduce load if oscillating. Increase acceleration/deceleration time constant if overshooting. Wire the encoder cable correctly.
82.1 Master-slave operation error 1	Cause: Driver communication error was detected. Remedy: Check it with the check method for [AL. 34.1].
84.1 Network module undetected error	Cause: (1) The network module was disconnected. (2) Noise/Environmental interference. (3) Network module malfunctioning. Remedy: Connect the network module correctly. Take countermeasures against noise (refer to "Noise reduction techniques"). Replace the network module or servo amplifier.
84.2 Network module initialization error 1	Cause: (1) Network module disconnected. (2) Incompatible network module connected. (3) Network cable disconnected or wiring incorrect. Remedy: Connect the module correctly. Replace with a network module compatible with the servo amplifier. Check wiring and connect cable correctly. Replace the network cable if malfunctioning.
84.3 Network module initialization error 2	Cause: See causes for 84.2. Remedy: Check it with the check method for [AL. 84.2].
85.1 Network module error 1	Cause: (1) Network module disconnected. (2) Network cable disconnected. (3) Wiring of network cable is incorrect. (4) Network cable malfunctioning. (5) Controller setting incorrect. Remedy: Connect module/cable correctly. Wire correctly. Replace the network cable. Review controller settings. Replace network module, servo amplifier, or controller if hardware failure.
86.1 Network communication error 1	Cause: (1) Network module disconnected. (2) Network cable disconnected. (3) Wiring incorrect. (4) Network disconnected by wrong procedure. (5) Data transmission interrupted. Remedy: Connect module correctly. Turn off control circuit power, connect cable correctly, then power on. Perform network connection according to correct procedure. Review controller communication setting. Take noise countermeasures.
8A.1 USB/Serial communication time-out error	Cause: (1) Communication commands have not been transmitted. (2) A communication cable was disconnected. (3) The servo amplifier is malfunctioning. Remedy: Transmit a command from the personal computer. Replace the communication cable. Replace the servo amplifier.
8A.2 Modbus RTU communication time-out error	Cause: (1) Communication commands have not been transmitted. (2) A communication cable was disconnected. Remedy: Transmit a command from the controller. Replace the communication cable. Replace the servo amplifier.
8D.1 CC-Link IE communication error 1	Cause: The MR-J3-T10 came off during communication. The Ethernet cable was disconnected or wiring is incorrect. Disconnected using the wrong procedure. Cable failure or transmission status abnormal (noise/temperature). Hardware failure (MR-J3-T10, Servo Amplifier, or Master Station). Remedy: Check if [AL. 74 Option card error 1] occurred. Turn off control circuit power and reconnect the Ethernet cable. Wire the Ethernet cable correctly. Replace the Ethernet cable. Take countermeasures against noise/temperature. Replace the MR-J3-T10, Servo Amplifier, or Master station if the error is repeatable.
8D.2 CC-Link IE communication error 2	Cause: Refer to causes for [AL. 8D.1]. Remedy: Check with the check method for [AL. 8D.1].
8D.3 Master station setting error 1	Cause: Station No. is set to a value other than 1 to 120. Network number is set to a value other than 1 to 239. Hardware malfunction (MR-J3-T10, Servo Amplifier, or Master Station). Remedy: Set the Station No. correctly ([Pr. Po02]). Set the Network number correctly ([Pr. Po03]). Replace the MR-J3-T10, Servo Amplifier, or Master Station.
8D.5 Master station setting error 2	Cause: A reserved station has been selected by the master station, and cyclic communication stopped. Remedy: Cancel the reserved station selection.
8D.6 CC-Link IE communication error 3	Cause: Refer to [AL. 8D.1]. Remedy: Check with the check method for [AL. 8D.1].
8D.7 CC-Link IE communication error 4	Cause: Transmission status abnormal (noise, ambient temp). Hardware malfunction (MR-J3-T10, Servo Amplifier, or Master Station). Remedy: Take countermeasures against noise or temperature. Replace the MR-J3-T10, Servo Amplifier, or Master Station.
8E.1 USB/Serial communication receive error	Cause: PC setting incorrect. Communication cable malfunction. Servo amplifier malfunction. Remedy: Review PC settings. Replace the communication cable. Replace the servo amplifier.
8E.2 USB/Serial communication checksum error	Cause: The setting of the personal computer is incorrect. Remedy: Review the settings on the personal computer.
8E.3 USB/Serial communication character error	Cause: Transmitted character out of specifications. Communication protocol failure. PC setting incorrect. Remedy: Correct the transmission data. Modify transmission data to accord with communication protocol. Review PC settings.
8E.6 Modbus RTU communication receive error	Cause: Setting of controller/servo amplifier (baud rate, parity, etc.) is incorrect. Communication cable malfunction. Servo amplifier malfunction. Remedy: Review the settings. Replace the communication cable. Replace the servo amplifier.
88._ / 8888._ Watchdog	Cause: The MR-J3-T10 came off during CC-Link IE communication. A part such as the CPU (or servo amplifier) is malfunctioning. Remedy: Check if [AL. 74 Option card error 1] occurred. Replace the servo amplifier.
90.1 Home position return incomplete	Cause: Home position return has not been performed. Operation executed without home position setting after [AL. 25] (Battery failure). Indexer method: [AL. E3] occurred simultaneously. Software stroke limit detected. Remedy: Execute a home position return. Check battery voltage/cable, remove failure, then execute home position return. Remove cause of [AL. E3] and perform home position return. Move machine within limit range and perform home position return.
90.2 Home position return abnormal termination	Cause: Proximity dog not connected. Stroke limit detected after start. Did not decelerate to creep speed (proximity dog turned off too early). Deceleration failed at indexer method. Remedy: Connect proximity dog correctly. Review stroke limit position/wiring. Review dog position, speed parameters, and travel distance. Review positional relationship of stroke limit and home position.
90.5 Z-phase unpassed	Cause: The Z-phase signal was not detected normally. Home position return executed but motor did not pass Z-phase. Remedy: Review the Z-phase signal and wiring. Review the setting position of the home position return start and proximity dog.
91.1 Main circuit device overheat warning	Cause: Ambient temperature of servo amplifier exceeded 55°C. Close mounting is out of specifications. Remedy: Lower the ambient temperature. Use within the range of specifications (check mounting distances).
92.1 Encoder battery cable disconnection warning	Cause: Battery was not connected to CN4 correctly. Battery cable disconnected or malfunctioning. Battery voltage is low/consumed. Encoder cable disconnected or shorted. Servo amplifier or Encoder malfunction. Remedy: Connect the battery correctly. Replace or repair the battery cable. Replace the battery (if less than 3.1 V DC). Replace or repair the encoder cable. Replace the servo amplifier or servo motor.
93.1 ABS data transfer warning	Cause: The Z-phase was not turned on at servo-on. The magnetic pole detection was executed. Remedy: Turn on the Z-phase and disable magnetic pole detection. Make home position setting again. Disable magnetic pole detection, cycle SON (Servo-on), and transfer ABS data.
95.1 STO1 off detection	Cause: STO1 not inputted correctly (wiring issue). STO1 turned off (enabled) under speed conditions. Servo amplifier malfunction. Safety component (e.g., MR-J3-D05) failure. Remedy: Wire correctly (or attach short-circuit connector if STO not used). Turn on STO1 (disabled). Replace the servo amplifier. Take corrective actions for the safety component.
95.3 STO warning 1	Cause: "Input device - Fixing-diagnosis execution selection at start-up" not executed. Parameters ([Pr. PSD27]/[Pr. PSD28]) set incorrectly. Wiring incorrect or noise interference. Functional safety unit malfunctioning. Remedy: Execute the fixing-diagnosis at start-up. Review the parameters. Review wiring and take noise countermeasures. Replace the functional safety unit.
95.4 STO warning 2 (safety observation function)	Cause: Test operation mode not set correctly. Safety communication error or network disconnected. Input mode selection [Pr. PSA02] incorrect. Incompatible functional safety unit connected. Safety communication setting [Pr. PSC04] incorrect. Servo amplifier or functional safety unit malfunction. Noise or ambient temperature issue. Remedy: Set test operation mode correctly. Check "Ab" display and take countermeasures for network trouble. Review [Pr. PSA02] and [Pr. PSC04] parameters. Replace functional safety unit (Software ver A2 or later required). Replace servo amplifier or functional safety unit. Take countermeasures against noise/temperature.
95.5 STO warning 3 (safety observation function)	Cause: STO command/SS1 command turned off (enabled) under specific speed conditions (e.g., 50 r/min or less). Remedy: Turn on (disable) STO command/SS1 command of the functional safety unit.
96.1 In-position warning at home positioning	Cause: INP (In-position) did not turn on within the specified time during home positioning. Remedy: Adjust gains to set droop pulses within the In-position range. Remove cause of droop pulse occurrence.
96.2 Command input warning at home positioning	Cause: Command already inputted at time of home positioning. Creep speed is too high. Remedy: Stop command input, set it after home positioning. Decelerate the creep speed.
96.3 Servo off warning at home positioning	Cause: Home positioning executed during servo-off. Remedy: Turn to servo-on, then execute home positioning.
96.4 Home positioning warning (Z-phase)	Cause: Z-phase was not turned on after servo-on. Remedy: Rotate the direct drive motor to turn on the Z-phase, then make home position setting.
97.1 Program operation disabled warning	Cause: Program started while "program operation disabled" was active (power not cycled after change). Remedy: Cycle the power of the servo amplifier.
97.2 Next station position warning	Cause: Abnormal value specified to signal input of next station. Number of stations per rotation [Pr. PT28] not specified correctly. Power not cycled after changing [Pr. PT28]. Remedy: Review parameter settings or next station position input signal. Cycle the power of the servo amplifier.
98.1 Forward rotation-side software stroke limit reached	Cause: Software limit set within actual operation range. Point table data exceeds software limit. JOG/Manual pulse operation reached limit. Remedy: Set [Pr. PT15] to [Pr. PT18] correctly. Correct the point table. Operate within software limit (adjust JOG speed/pulse multiplication).
98.2 Reverse rotation-side software stroke limit reached	Cause: See 98.1 causes. Remedy: See 98.1 remedies.
99.1 Forward rotation stroke end off	Cause: Limit switch (LSP) not connected. Forward rotation stroke end exceeded during driving. Remedy: Connect limit switch correctly. Check operation pattern.
99.2 Reverse rotation stroke end off	Cause: Limit switch (LSN) not connected or stroke end exceeded. Remedy: Connect limit switch correctly or check operation pattern.
9A.1 Optional unit input data sign error	Cause: MR-D01 connection issue, sign setting issue (+/-), or unit malfunction. Remedy: Connect MR-D01 correctly. Turn on only one sign. Replace MR-D01.
9A.2 Optional unit BCD input data error	Cause: Value other than "0" to "9" is set in a digit. Remedy: Set a value from "0" to "9".
9B.1 Excess droop pulse 1 warning	Cause: Motor power cable disconnected or wired incorrectly (U/V/W). Encoder cable connection incorrect. Torque limit enabled/insufficient. Collision with machine. Power supply voltage dropped. Accel/decel time too short. Position loop gain too small. Remedy: Repair/replace motor cable; check wiring. Increase torque limit or motor capacity. Check operation pattern (collision). Check power supply capacity. Increase accel/decel time constant. Increase position loop gain [Pr. PB08].
9B.4 Error excessive warning during 0 torque limit	Cause: The torque limit has been set to 0. Remedy: Do not input a command while the torque limit value is 0.
9C.1 Converter unit warning	Cause: A warning occurred in the converter unit during servo-on. Remedy: Check the warning of the converter unit and take action following its manual.
9D.1 Station number switch change warning	Cause: Station No. switch setting changed after power-on or servo amplifier malfunction. Remedy: Restore the setting (do not change after power-on). Replace servo amplifier if necessary.
9D.2 Master station setting warning	Cause: Station specific mode mismatch between master and servo. Incorrect master station type or cyclic points. [Pr. PSA02] or connection wiring incorrect (MR-D30). Remedy: Review station mode and [Pr. PN03]. Correct master station settings. Connect wiring correctly.
9E.1 CC-Link IE warning	Cause: Incorrect slide switch combination (SW1-1/SW1-2). Transmission status abnormal (noise). Ethernet cable disconnected or wired incorrectly. Master station communication settings ([Pr. Po02], [Pr. Po03]) incorrect. Remedy: Set slide switches correctly (SW1-1 OFF, SW1-2 ON for Basic). Take countermeasures against noise. Repair/Replace Ethernet cable. Review communication settings.
9F.1 Low battery	Cause: Battery not connected to CN4. Battery voltage low (consumed). Encoder cable problem. Remedy: Connect battery correctly. Replace the battery (less than 4.9V). Repair or replace encoder cable.
E0.1 Excessive regeneration warning	Cause: Regenerative power exceeded 85% of permissible power. Remedy: Reduce positioning frequency. Increase deceleration time constant. Reduce load. Use a regenerative option.
E1.1 Thermal overload warning 1 (during operation)	Cause: Load was over 85% to the alarm level of [AL. 50.1]. Remedy: Reduce load, check operation pattern (See check method for AL. 50.1).
E1.3 Thermal overload warning 3 (during operation)	Cause: Load was over 85% to the alarm level of [AL. 51.1]. Remedy: Reduce load (See check method for AL. 51.1).
E2.1 Servo motor temperature warning	Cause: Motor temperature reached 85% of occurrence level of [AL 46.2]. Remedy: Check effective load ratio and cooling status (See check method for AL. 46.2).
E3.1 Multi-revolution counter travel distance excess	Cause: Travel distance from home position is 32768 rev or more. Remedy: Review operation range. Execute home position return again. Cycle power.
E3.2 Absolute position counter warning	Cause: Noise/Ambient device caused data corruption, or encoder malfunction. Remedy: Take countermeasures against noise. Cycle power and home position return. Replace servo motor if persistent.
E4.1 Parameter setting range error warning	Cause: A parameter was set out of range with the servo system controller. Remedy: Set the parameter within the valid range.
E5.1 Time-out during ABS data transfer	Cause: I/O signal wiring incorrect/loose. Sequence program incorrect. Remedy: Repair or replace I/O signal wire. Modify the sequence program.
E6.1 Forced stop warning	Cause: EM2/EM1 (Forced stop) turned off. External 24 V DC power supply is off. Remedy: Ensure safety and turn on EM2/EM1. Input the 24 V DC power supply.
95.4 STO warning 2 (safety observation function)	Cause: Test operation mode not set correctly. Safety communication error or network disconnected. Input mode selection [Pr. PSA02] incorrect. Incompatible functional safety unit connected. Safety communication setting [Pr. PSC04] incorrect. Servo amplifier or functional safety unit malfunction. Noise or ambient temperature issue. Remedy: Set test operation mode correctly. Check "Ab" display and take countermeasures for network trouble. Review [Pr. PSA02] and [Pr. PSC04] parameters. Replace functional safety unit (Software ver A2 or later required). Replace servo amplifier or functional safety unit. Take countermeasures against noise/temperature.
95.5 STO warning 3 (safety observation function)	Cause: STO command/SS1 command turned off (enabled) under specific speed conditions (e.g., 50 r/min or less). Remedy: Turn on (disable) STO command/SS1 command of the functional safety unit.
96.1 In-position warning at home positioning	Cause: INP (In-position) did not turn on within the specified time during home positioning. Remedy: Adjust gains to set droop pulses within the In-position range. Remove cause of droop pulse occurrence.
96.2 Command input warning at home positioning	Cause: Command already inputted at time of home positioning. Creep speed is too high. Remedy: Stop command input, set it after home positioning. Decelerate the creep speed.
96.3 Servo off warning at home positioning	Cause: Home positioning executed during servo-off. Remedy: Turn to servo-on, then execute home positioning.
96.4 Home positioning warning (Z-phase)	Cause: Z-phase was not turned on after servo-on. Remedy: Rotate the direct drive motor to turn on the Z-phase, then make home position setting.
97.1 Program operation disabled warning	Cause: Program started while "program operation disabled" was active (power not cycled after change). Remedy: Cycle the power of the servo amplifier.
97.2 Next station position warning	Cause: Abnormal value specified to signal input of next station. Number of stations per rotation [Pr. PT28] not specified correctly. Power not cycled after changing [Pr. PT28]. Remedy: Review parameter settings or next station position input signal. Cycle the power of the servo amplifier.
98.1 Forward rotation-side software stroke limit reached	Cause: Software limit set within actual operation range. Point table data exceeds software limit. JOG/Manual pulse operation reached limit. Remedy: Set [Pr. PT15] to [Pr. PT18] correctly. Correct the point table. Operate within software limit (adjust JOG speed/pulse multiplication).
98.2 Reverse rotation-side software stroke limit reached	Cause: See 98.1 causes. Remedy: See 98.1 remedies.
99.1 Forward rotation stroke end off	Cause: Limit switch (LSP) not connected. Forward rotation stroke end exceeded during driving. Remedy: Connect limit switch correctly. Check operation pattern.
99.2 Reverse rotation stroke end off	Cause: Limit switch (LSN) not connected or stroke end exceeded. Remedy: Connect limit switch correctly or check operation pattern.
9A.1 Optional unit input data sign error	Cause: MR-D01 connection issue, sign setting issue (+/-), or unit malfunction. Remedy: Connect MR-D01 correctly. Turn on only one sign. Replace MR-D01.
9A.2 Optional unit BCD input data error	Cause: Value other than "0" to "9" is set in a digit. Remedy: Set a value from "0" to "9".
9B.1 Excess droop pulse 1 warning	Cause: Motor power cable disconnected or wired incorrectly (U/V/W). Encoder cable connection incorrect. Torque limit enabled/insufficient. Collision with machine. Power supply voltage dropped. Accel/decel time too short. Position loop gain too small. Remedy: Repair/replace motor cable; check wiring. Increase torque limit or motor capacity. Check operation pattern (collision). Check power supply capacity. Increase accel/decel time constant. Increase position loop gain [Pr. PB08].
9B.4 Error excessive warning during 0 torque limit	Cause: The torque limit has been set to 0. Remedy: Do not input a command while the torque limit value is 0.
9C.1 Converter unit warning	Cause: A warning occurred in the converter unit during servo-on. Remedy: Check the warning of the converter unit and take action following its manual.
9D.1 Station number switch change warning	Cause: Station No. switch setting changed after power-on or servo amplifier malfunction. Remedy: Restore the setting (do not change after power-on). Replace servo amplifier if necessary.
9D.2 Master station setting warning	Cause: Station specific mode mismatch between master and servo. Incorrect master station type or cyclic points. [Pr. PSA02] or connection wiring incorrect (MR-D30). Remedy: Review station mode and [Pr. PN03]. Correct master station settings. Connect wiring correctly.
9E.1 CC-Link IE warning	Cause: Incorrect slide switch combination (SW1-1/SW1-2). Transmission status abnormal (noise). Ethernet cable disconnected or wired incorrectly. Master station communication settings ([Pr. Po02], [Pr. Po03]) incorrect. Remedy: Set slide switches correctly (SW1-1 OFF, SW1-2 ON for Basic). Take countermeasures against noise. Repair/Replace Ethernet cable. Review communication settings.
9F.1 Low battery	Cause: Battery not connected to CN4. Battery voltage low (consumed). Encoder cable problem. Remedy: Connect battery correctly. Replace the battery (less than 4.9V). Repair or replace encoder cable.
E0.1 Excessive regeneration warning	Cause: Regenerative power exceeded 85% of permissible power. Remedy: Reduce positioning frequency. Increase deceleration time constant. Reduce load. Use a regenerative option.
E1.1 Thermal overload warning 1 (during operation)	Cause: Load was over 85% to the alarm level of [AL. 50.1]. Remedy: Reduce load, check operation pattern (See check method for AL. 50.1).
E1.3 Thermal overload warning 3 (during operation)	Cause: Load was over 85% to the alarm level of [AL. 51.1]. Remedy: Reduce load (See check method for AL. 51.1).
E2.1 Servo motor temperature warning	Cause: Motor temperature reached 85% of occurrence level of [AL 46.2]. Remedy: Check effective load ratio and cooling status (See check method for AL. 46.2).
E3.1 Multi-revolution counter travel distance excess	Cause: Travel distance from home position is 32768 rev or more. Remedy: Review operation range. Execute home position return again. Cycle power.
E3.2 Absolute position counter warning	Cause: Noise/Ambient device caused data corruption, or encoder malfunction. Remedy: Take countermeasures against noise. Cycle power and home position return. Replace servo motor if persistent.
E4.1 Parameter setting range error warning	Cause: A parameter was set out of range with the servo system controller. Remedy: Set the parameter within the valid range.
E5.1 Time-out during ABS data transfer	Cause: I/O signal wiring incorrect/loose. Sequence program incorrect. Remedy: Repair or replace I/O signal wire. Modify the sequence program.
E6.1 Forced stop warning	Cause: EM2/EM1 (Forced stop) turned off. External 24 V DC power supply is off. Remedy: Ensure safety and turn on EM2/EM1. Input the 24 V DC power supply.
E7 Controller forced stop warning	Cause: The forced stop signal of the servo system controller was inputted. The forced stop signal was inputted via Modbus RTU communication. Remedy: Ensure safety and cancel the forced stop signal of the controller.
E8 Cooling fan speed reduction warning	Cause: Foreign matter caught in the cooling fan. Cooling fan life has expired. Remedy: Remove the foreign matter. Replace the servo amplifier if fan life exceeded.
E9 Main circuit off warning	Cause: Main circuit power supply is off or wiring (P3/P4 or P1/P2) is disconnected. Magnetic contactor control connector disconnected. Bus bar between converter/drive unit disconnected. Parameter setting [Pr. PA02] or [Pr. PC27/PC05] contradicts wiring. Bus voltage dropped during operation (under 50 r/min). Servo amplifier or converter unit malfunction. Remedy: Turn on the main circuit power. Connect wiring/bus bars correctly. Review parameter settings [Pr. PA02], [Pr. PC27], [Pr. PC05]. Review power supply capacity. Increase acceleration time constant. Replace the servo amplifier or converter unit.
EA ABS servo-on warning	Cause: The servo-on was not enabled within 1s after ABSM (ABS transfer mode) was turned on. The wiring of I/O signals is incorrect or loose. The sequence program is incorrect. Remedy: Repair or replace the I/O signal wire. Modify the sequence program.
EB The other axis error warning	Cause: [AL. 24 Main circuit error] or [AL. 32 Overcurrent] occurred on the other axis. "All alarms" is selected in [Pr. PF02] "Target alarm selection of other axis error warning". Remedy: Eliminate the cause of the alarm on the other axis side. Remove the cause of the occurring alarm at the other axis.
EC Overload warning 2	Cause: Operations over rated output were repeated while the servo motor shaft was not rotated. The load is too large or the capacity is not enough. Remedy: Reduce the load. Replace the servo motor with one of larger capacity.
ED Output watt excess warning	Cause: Output wattage (speed × torque) exceeded 120% of rated output continuously. Remedy: Reduce the servo motor speed. Reduce the load.
F0 Tough drive warning	Cause: Instantaneous power failure: Control circuit power supply voltage dropped. Vibration: Machine resonance suppression filter value changed frequently due to resonance. Remedy: Check power supply voltage (Refer to AL. 10.1 remedies). Set the machine resonance suppression filter manually. Check machine status for loose screws/parts.
F2 Drive recorder - Miswriting warning	Cause: Flash-ROM malfunctioning (area writing timeout). Data not written to drive recorder area. Remedy: Disconnect cables (except control power), check repeatability. Replace servo amplifier if repeatable. Check if clearing alarm history disables this alarm with MR Configurator2.
F3 Oscillation detection warning	Cause: Oscillation detection logic triggered. Remedy: Check with the check method for [AL. 54.1].
F4 Positioning warning	Cause: Target position set out of range. Acceleration/Deceleration time constant set out of range ([Pr. PT49], [Pr. PT50]). Home position return type set out of setting range ([Pr. PT45]). Remedy: Set the target position correctly. Set acceleration/deceleration time constants correctly. Set home position return type correctly. Cancel the warning (turn on C_ORST).
F5 Simple cam function - Cam data miswriting warning	Cause: Flash-ROM malfunctioning. Cam data checksum error (noise entry or power off during write). Remedy: Replace the servo amplifier. After writing cam data again, cycle the power. If writing temporally, turn on cam control command again.
F6 Simple cam function - Cam control warning	Cause: Cam axis one cycle current value restoration failed. Cam axis feed current value restoration failed. Cam unregistered error (data never written or lost). Cam control data setting range error. Cam control inactive (power not cycled after write, or servo-off during cam control). Remedy: Move feed current value to within stroke in reciprocating motion pattern. Write the cam data. Set cam control data correctly. Cycle the power. Turn on cam control command during servo-on.
F7 Machine diagnosis warning	Cause: Vibration failure: Servo system unstable/oscillating or vibration increased due to part deterioration. Friction failure: Friction changes due to environment or part deterioration. Total travel distance: Servo motor total travel distance exceeds threshold. Remedy: Adjust servo gain (auto tuning) or set resonance suppression filter. Set larger threshold multiplication ([Pr. PF40]). Maintain equipment and replace parts. After replacing equipment, reset servo motor total travel distance.
61 Overcurrent	Cause: A current higher than the permissible current was applied to the power regeneration converter unit. Potential causes include: (1) Incorrect combination of AC reactor and converter unit. (2) Current exceeds instantaneous maximum rating. (3) Insufficient power supply capacity. (4) Unbalanced input power supply phases. (5) Noise or grounding issues. (6) Converter unit malfunction. Remedy: Connect the correct AC reactor. Check operation pattern or increase the capacity of the power regeneration converter unit. Check and ensure sufficient power supply capacity. Improve the balance of power supply phases. Take countermeasures against noise and grounding issues. Replace the power regeneration converter unit.
62 Frequency error	Cause: The frequency of the input power supply exceeds the permissible range. Potential causes include: (1) Main circuit power supply is turned off. (2) Input frequency is out of specifications. (3) Unstable power supply voltage during operation. (4) Noise or grounding issues. (5) Converter unit malfunction. Remedy: Turn on the main circuit power supply. Check the power supply frequency (should be within 50 Hz ± 3% or 60 Hz ± 3%). Check the power supply stability during motor acceleration/deceleration. Take countermeasures against noise and grounding issues. Replace the power regeneration converter unit.
66 Process error	Cause: The process did not complete within the specified time. (1) Noise or shorted connector. (2) Converter unit malfunction. Remedy: Check power supply for noise and connectors for shorts; take countermeasures. Replace the power regeneration converter unit.
67 Open phase	Cause: (1) Wiring of L1, L2, and L3 is incorrect or disconnected. (2) Converter unit malfunction. Remedy: Review and correct the wiring of L1, L2, and L3. Replace the power regeneration converter unit.
68 Watchdog	Cause: A part such as the CPU is malfunctioning. Remedy: Replace the power regeneration converter unit.
69 Ground fault	Cause: A ground fault occurred on the servo motor power lines. (1) Ground fault at servo motor power cable. (2) Ground fault at servo motor. (3) Servo amplifier malfunction. (4) Converter unit malfunction. Remedy: Replace the servo motor power cable. Replace the servo motor. Replace the servo amplifier. Replace the power regeneration converter unit.
6A MC drive circuit error	Cause: Failure of the magnetic contactor drive circuit. (1) Rotary switch setting contradicts wiring constitution. (2) Magnetic contactor failed. (3) Converter unit malfunction. Remedy: Check and correct the setting of the rotary switch or wiring constitution. Replace the magnetic contactor. Replace the power regeneration converter unit.
6B Inrush current suppression circuit error	Cause: (1) Inrush relay turned on and off very frequently. (2) Inrush current suppressor circuit is malfunctioning. Remedy: Check and adjust the operation pattern. Replace the power regeneration converter unit.
6C Main circuit error	Cause: An error was detected when the main circuit capacitor was charged. (1) Total capacity of connected amplifiers exceeds permissible capacity. (2) Converter unit malfunction. (3) Servo amplifier malfunction. Remedy: Review and reduce the capacity of connected servo amplifiers. Replace the power regeneration converter unit. Replace the servo amplifier.
6E Board error	Cause: (1) Converter unit is malfunctioning. (2) Noise from nearby devices. Remedy: Replace the power regeneration converter unit. Take countermeasures against noise.
70 Converter forced stop error	Cause: (1) EM1 (Forced stop) was turned off. (2) External 24 V DC power supply is off. (3) Converter unit malfunction. Remedy: Ensure safety and turn on EM1 (Forced stop). Input the 24 V DC power supply. Replace the power regeneration converter unit.
71 Undervoltage	Cause: (1) Power supply wiring is incorrect. (2) Power supply voltage is low. (3) Instantaneous power failure (> 60 ms). (4) Converter unit malfunction. Remedy: Wire the power supply correctly. Review the power supply voltage. Review the power source stability. Replace the power regeneration converter unit.
72 Cooling fan error	Cause: The speed of the cooling fan decreased. (1) Foreign matter caught in the fan. (2) Cooling fan life expired. Remedy: Remove the foreign matter. Replace the power regeneration converter unit.
73 Regenerative error	Cause: The regenerative load ratio exceeded 100%. Remedy: Reduce the frequency of positioning. Reduce the load.
75 Overvoltage	Cause: Bus voltage exceeded prescribed value (200V class: >420V, 400V class: >840V). (1) Insufficient regeneration capacity. (2) High power supply voltage. (3) Ground fault/short in servo motor cable. (4) Ground fault at servo motor. (5) Noise. Remedy: Check operation pattern or use a larger converter unit. Reduce the power supply voltage. Replace the servo motor power cable. Replace the servo motor. Take countermeasures against noise.
76 Switch setting error	Cause: (1) Rotary switch setting is incorrect. (2) Forced stop input disabled by rotary switch but wiring exists. (3) Converter unit malfunction. Remedy: Set the rotary switch correctly. Check wiring and rotary switch settings. Replace the power regeneration converter unit.
77 Main circuit device overheat	Cause: (1) Ambient temperature exceeded 55 °C. (2) Frequent on/off under overload status. (3) Clogged cooling fan/heat sink. (4) Converter unit malfunction. Remedy: Lower the ambient temperature. Check operation pattern. Clean the cooling fan/heat sink periodically. Replace the power regeneration converter unit.
7E Overload 1	Cause: Continuous output current exceeded the overload protection characteristic. Remedy: Reduce the load. Check operation pattern.
7F Overload 2	Cause: Short-term output current exceeded the overload protection characteristic. Remedy: Check operation pattern.
E9 Instantaneous power failure warning	Cause: Instantaneous power failure occurred for 30 ms or longer ([AL. 71] may occur). Remedy: Review the power supply.
EA External forced stop warning	Cause: (1) EM1 turned off. (2) External 24 V DC power supply is off. (3) Converter unit malfunction. Remedy: Ensure safety and turn on EM1. Input the 24 V DC power supply. Replace the power regeneration converter unit.
EB Excessive regeneration warning	Cause: Regenerative load ratio exceeded 80% ([AL. 73] may occur). Remedy: Reduce the frequency of positioning. Reduce the load.
EC Overload warning	Cause: Warning level for Overload 1 or 2 reached ([AL. 7E] may occur). Remedy: Check remedies for Overload 1 (7E) and Overload 2 (7F).
EE Cooling fan speed reduction warning	Cause: Cooling fan speed decreased to warning level ([AL. 72] may occur). Remedy: Check remedies for Cooling fan error (72).
15 Memory error 2 (EEP-ROM)	Cause: Failure of the part (EEP-ROM) in the resistance regeneration converter unit. (1) EEP-ROM is malfunctioning at power on. (2) The number of write times to EEP-ROM exceeded 100,000. (3) EEP-ROM is malfunctioning during normal operation. (4) Something near the device caused it (noise/short). Remedy: Disconnect cables except for control circuit power supply and check repeatability. Check if parameters have been used very frequently (reduce usage if changed). Check if error occurs when changing parameters during normal operation. Check power supply for noise and check if connector is shorted. Replace the resistance regeneration converter unit if the error is repeatable.
17 Board error	Cause: A part in the resistance regeneration converter unit is malfunctioning. (1) Recognition signal was not read properly. (2) Something near the device caused it (noise, ambient temp). Remedy: Disconnect cables except for control circuit power supply and check repeatability. Check the noise, ambient temperature, etc. Replace the resistance regeneration converter unit if repeatable.
19 Memory error 3 (Flash-ROM)	Cause: A part (Flash-ROM) in the resistance regeneration converter unit is failure. (1) The Flash-ROM is malfunctioning. (2) Something near the device caused it. Remedy: Disconnect cables except for control circuit power supply and check repeatability. Check noise and ambient temperature. Replace the resistance regeneration converter unit if repeatable.
30 Regenerative error	Cause: Permissible regenerative power exceeded, or resistor/transistor malfunctioning. (1) Setting of regenerative resistor/option is incorrect. (2) Regenerative resistor is not connected. (3) Incorrect combination of resistor and converter unit. (4) Power supply voltage high. (5) Regenerative load ratio exceeded 100%. (6) Wire breakage of regenerative resistor. (7) Failure of detection circuit. (8) Regenerative transistor malfunction. (9) Noise/Ground fault/Ambient temp. Remedy: Check [Pr. PA01] setting value and set correctly. Connect the regenerative resistor correctly. Use the correct combination of converter and resistor. Check input voltage (200V class: <260V AC, 400V class: <520V AC). Reduce positioning frequency, load, or review regenerative option capacity. Measure resistance; replace resistor if abnormal. Check if resistor is overheating abnormally. Replace the resistance regeneration converter unit.
33 Overvoltage	Cause: Bus voltage exceeded prescribed value (200V class: >400V DC, 400V class: >800V DC). (1) Regenerative resistor not used/set. (2) Setting of regenerative resistor incorrect. (3) Regenerative resistor not connected. (4) Wire breakage of resistor. (5) Insufficient regeneration capacity. (6) Power supply voltage high. (7) Ground fault/short at servo motor cable. (8) Noise/Temperature. (9) High impedance/leak current. Remedy: Use the regenerative resistor (option). Correctly set [Pr. PA01]. Check/Fix connections to the resistor. Measure resistance; replace resistor if abnormal. Use a regenerative resistor with larger capacity. Reduce power supply voltage. Check/Replace servo motor power cable if shorted.
37 Parameter error	Cause: Parameter setting value is incorrect. (1) Parameter set out of setting range. (2) Regenerative resistor not used but set in [Pr. PA01]. (3) Number of write times to EEP-ROM exceeded 100,000. (4) Parameter setting changed due to malfunction. Remedy: Set parameter within the correct range. Correct [Pr. PA01] setting. Change process to use parameters less frequently if write limit exceeded. Replace the resistance regeneration converter unit.
38 MC drive circuit error	Cause: Magnetic contactor drive circuit is malfunctioning. (1) Incorrect connection to connector (CNP1). (2) [Pr. PA02] setting contradicts wiring. (3) Main circuit power supply voltage is low. (4) Magnetic contactor failed. (5) Magnetic contactor drive circuit malfunctioning. (6) Part failure in converter unit. Remedy: Connect CNP1 correctly. Review [Pr. PA02] setting and wiring. Increase the voltage of the main circuit power supply. Replace the magnetic contactor. Replace the resistance regeneration converter unit.
39 Open phase	Cause: The wirings of L1/L2/L3 are incorrect. (1) Any of the wirings L1/L2/L3 is disconnected. (2) A part in the resistance regeneration converter unit is failure. Remedy: Review the wiring. Replace the resistance regeneration converter unit.
3A Inrush current suppression circuit error	Cause: The inrush current suppression circuit error was detected. (1) Turning on/off of inrush relay repeated very frequently. (2) Inrush current suppressor circuit is malfunctioning. Remedy: Check operation pattern (reduce frequency of on/off). Replace the resistance regeneration converter unit.
45 Main circuit device overheat	Cause: The inside of the resistance regeneration converter unit overheated. (1) Ambient temperature exceeded 55 °C. (2) Turning on/off repeated under overload status. (3) Cooling fan, heat sink, or openings clogged. (4) Resistance regeneration converter unit malfunctioning. Remedy: Lower the ambient temperature. Check operation pattern to avoid frequent overload. Clean the cooling fan, heat sink, or openings periodically. Replace the resistance regeneration converter unit.

 

How to Read MR-J4 Faults via Display & Software

Servo diagnostics require checking both the electrical drive and the mechanical load. You can diagnose the MR-J4 using the physical display or the MR Configurator2 software.

1. 7-Segment LED Display

The display on the front of the amplifier indicates the drive status:
Normal Operation: Displays the axis number or status (e.g., ‘b1’, ‘d1’).
Alarm Mode: Flashes “AL.” followed by a two or three-digit code (e.g., AL.32).
Warning Mode: Flashes a code (often starting with 9, E, or F) indicating a non-critical issue that needs attention.

2. MR Configurator2 (Software)

Connecting a PC via USB (Mini-B) is the most effective way to troubleshoot in 2026. The Alarm Display in MR Configurator2 provides:

• Alarm History: The last 16 alarms with precise timestamps (in running hours).
• Detailed Information: Clicking an alarm reveals the “Cause” and “Check” points specific to that instance.
• Drive Recorder: This feature graphs the motor speed, torque, and current waveform before and after the alarm occurred, which is critical for analyzing Overload (AL.50) or Error Excessive (AL.52) faults.

3. Life Diagnosis Function

The MR-J4 calculates the estimated life of internal capacitors and relays. If you see warnings related to component life, check the “Life Diagnosis” tab in the software to plan maintenance before a hard failure occurs.

---

Frequently Asked Questions (FAQ)

Q: How do I fix Alarm AL.25 (Absolute Position Lost)?

A: This is one of the most common MR-J4 errors. It usually means the battery backing up the absolute encoder has died or was disconnected while the power was off.
Fix: Replace the battery (MR-BAT6V1SET or similar). Afterward, you must perform the Home Position Return (Homing) procedure again to re-establish the zero point.

Q: How do I reset a Mitsubishi MR-J4 Alarm?

A: There are two types of resets depending on the severity of the alarm:

• Power Cycle: Major alarms (like AL.32 Overcurrent or AL.10 Undervoltage) usually require turning the main power OFF and ON again.
• Alarm Reset Command: Minor alarms can be cleared by toggling the RES (Reset) input signal or clicking the “Error Reset” button in MR Configurator2.

Q: What does AL.50 (Overload 1) or AL.51 (Overload 2) mean?

A: This indicates the motor is working beyond its continuous rating.
Causes: Mechanical binding/jamming, brake not releasing, aggressive acceleration/deceleration parameters, or an undersized motor for the application.