Unidrive HS30 Drive Fault Codes

Comprehensive troubleshooting guide for Control Techniques Unidrive HS30. Learn to interpret high-speed spindle trips, OI.AC, and It.AC errors using Connect software.

Unidrive HS30 Fault Codes Reference Table

Below is the complete reference list of trips for the Unidrive HS30. Please note that many trips include sub-codes which provide specific details about the internal hardware state at the time of the fault.

Unidrive M300/HS30 Diagnostics

Fault Code and Meaning	Cause and Remedy
C.Acc NV Media Card Write fail	Cause: Unable to access the NV Media Card. Remedy: Check if the card is properly inserted. Replace the NV Media Card.
C.by NV Media Card busy	Cause: An attempt has been made to access a file on NV Media Card, but the NV Media Card is already being accessed by an option module. No data is transferred.
C.cPr NV Media Card file/data is different to the one in the drive	Cause: A C.cPr trip is initiated if the parameters on the NV Media Card are different to the drive.
C.d.E NV Media Card data location already contains data	Cause: Attempt has been made to store data on a NV Media Card in a data block which already contains data.
C.dAt NV Media Card data not found	Cause: Attempt has been made to access non-existent file or block on the NV Media Card.
C.Err NV Media Card data structure error	Cause: Attempt has been made to access the NV Media Card but an error has been detected in the data structure on the card. Remedy: Resetting the trip will cause the drive to erase and create the correct folder structure.
C.FuL NV Media Card full	Cause: There is not enough space left on the card.
C.OPt Option modules installed are different between source drive and destination drive	Cause: The parameter data or default difference data is being transferred from the NV Media Card to the drive, but the option module category is different between the source and destination drives.
C.Pr NV Media Card data blocks are not compatible with the drive derivative	Cause: Drive Derivative is different between the source and target drives. Remedy: Refer to Control User Guide.
C.rdo NV Media Card has the Read Only bit set	Cause: Attempt has been made to modify a read-only NV Media Card or a read-only data block.
C.rtg Voltage and/or current rating of the source and destination drives are different	Cause: The current and / or voltage ratings are different between source and destination drives.
C.SL Option module file transfer has failed	Cause: The C.SL trip is initiated if the transfer of an option module file to or from a module failed because the option module does not respond correctly.
C.tyP NV Media Card parameter set not compatible with current drive mode	Cause: The drive mode in the data block on the NV Media Card is different from the current drive mode.
cL.A1 Analog input 1 current loss	Cause: Current loss was detected in current mode on Analog input 1 (Terminal 2).
CL.bt Trip initiated from the Control Word	Cause: Initiated by setting bit 12 on the control word when the control word is enabled. Remedy: Refer to Parameter Reference Guide.
Cur.c Current calibration range	Cause: Current calibration range error.
Cur.O Current feedback offset error	Cause: Current offset is too large to be trimmed.
d.Ch Drive parameters are being changed	Cause: A user action or a file system write is active that is changing the drive parameters and the drive has been commanded to enable.
dEr.E Derivative file error	Cause: Derivative file error. Remedy: Contact the supplier of the drive.
dEr.I Derivative product image error	Cause: Derivative product image error. Remedy: Contact the supplier of the drive.
dESt Two or more parameters are writing to the same destination parameter	Cause: The dESt trip indicates that destination output parameters of two or more logic functions within the drive are writing to the same parameter.
dr.CF Drive configuration	Cause: Drive configuration error. Remedy: Contact the supplier of the drive.
EEF Default parameters have been loaded	Cause: The EEF trip indicates that default parameters have been loaded. The exact cause/reason of the trip can be identified from the sub-trip number. Remedy: See Control User Guide.
Et An External trip is initiated	Cause: The cause of the trip can be identified from the sub trip number displayed after the trip string (e.g., Sub-trip 1 = External Trip). Remedy: Refer to Control User Guide.
FAn.F Fan fail	Cause: Indicates the fan or fan circuitry has failed.
Fi.Ch File changed	Cause: A file has been changed. Remedy: Power cycle to clear the trip.
FI.In Firmware Incompatibility	Cause: The user firmware is incompatible with the power firmware.
HFxx trip Hardware faults	Cause: Internal drive hardware fault. Remedy: See Control User Guide.
It.Ac Output current overload timed out (I²t)	Cause: The It.Ac trip indicates a motor thermal overload based on the output current and motor thermal time constant. The drive will trip on It.Ac when the accumulator gets to 100%. This can occur when there is excessive mechanical load. Remedy: Ensure the load is not jammed / sticking. Check the load on the motor has not changed. Ensure the motor rated current is not zero.
It.br Braking resistor overload timed out (I²t)	Cause: Braking resistor overload has timed out. This can be caused by excessive braking resistor energy.
no.PS No power board	Cause: No communication between the power and control boards.
O.Ld1 Digital output overload	Cause: The total current drawn from 24 V user supply or from the digital output has exceeded the limit.
O.SPd Motor frequency has exceeded the over frequency threshold	Cause: Excessive motor speed (typically caused by mechanical load driving the motor).
Oh.br Braking IGBT over-temperature	Cause: Braking IGBT over-temperature. Detected by thermal model.
Oh.dc DC bus over temperature	Cause: DC bus component over temperature based on a software thermal model.
Oht.C Control stage over-temperature	Cause: Control stage over-temperature detected.
Oht.I Inverter over temperature based on thermal model	Cause: IGBT junction over-temperature has been detected based on a software thermal model.
Oht.P Power stage over temperature	Cause: This trip indicates that a power stage over-temperature has been detected.
OI.A1 Analog input 1 over-current	Cause: Current input on analog input 1 exceeds 24 mA.
OI.AC Instantaneous output over current detected	Cause: The instantaneous drive output current has exceeded the set limit. Remedy: Increase acceleration/deceleration rate. If seen during autotune reduce the voltage boost. Check for short circuit on the output cabling. Check integrity of the motor insulation using an insulation tester. Is the motor cable length within limits for the frame size? Reduce the values in the current loop gain parameters.
OI.br Braking IGBT over current detected	Cause: Over current has been detected in braking IGBT or braking IGBT protection has been activated. Short circuit protection for the braking IGBT activated. Remedy: Check brake resistor wiring. Check braking resistor value is greater than or equal to the minimum resistance value. Check braking resistor insulation.
OI.SC Output phase short-circuit	Cause: Over-current detected on drive output when enabled.
OPt.d Option module does not acknowledge during drive mode changeover	Cause: Option module did not acknowledge notifying the drive that communications with the drive has been stopped during the drive mode changeover within the allocated time.
Out.P Output phase loss detected	Cause: Phase loss has been detected at the drive output.
OV DC bus voltage has exceeded the peak level or maximum continuous level	Cause: The OV trip indicates that the DC bus voltage has exceeded the maximum limit (exceeded for 15 seconds). Remedy: Increase Deceleration Rate 1 (Pr 04). Decrease the braking resistor value (staying above the minimum value). Check nominal AC supply level. Check for supply disturbances which could cause the DC bus to rise. Check motor insulation using an insulation tester.
P.dAt Power system configuration data error	Cause: Power system configuration data error. Remedy: Contact the supplier of the drive.
PAd Keypad has been removed	Cause: The PAd trip indicates that the drive is in keypad mode and the keypad has been disconnected from the drive.
Pb.bt Power board is in bootloader mode	Cause: Power board is in bootloader mode.
Pb.Er Communication has been lost / errors detected between power control	Cause: Communications loss between power and control.
Pb.HF Power board HF	Cause: Power processor hardware fault. Remedy: Contact the supplier of the drive.
Pd.S Power down save error	Cause: Error has been detected in the power down save parameters saved in non-volatile memory.
PH.Lo Supply phase loss	Cause: The drive has detected an input phase loss or large supply imbalance.
PSU Internal power supply fault	Cause: One or more internal power supply rails are outside limits or overloaded.
r.ALL RAM allocation error	Cause: Option module derivative image has requested more parameter RAM than is allowed.
r.b.ht Hot rectifier/brake	Cause: Over-temperature detected on input rectifier or braking IGBT.
rS Measured resistance has exceeded the parameter range	Cause: The measured stator resistance during an autotune test has exceeded the maximum possible value of Stator Resistance. Remedy: Refer to the Control User Guide.
SCL Control word watchdog has timed out	Cause: The control word has been enabled and has timed out. Remedy: Check control word timing and logic.
SL.dF Option module in option slot 1 has changed	Cause: Option slot 1 on the drive is a different type to that installed when parameters were last saved on the drive. Remedy: Confirm if the change in module was intentional. Save parameters to accept the new configuration.
SL.Er Option module in option slot 1 has detected a fault	Cause: Option module in option slot 1 on the drive has detected an error. Remedy: Check the specific option module documentation for error details.
SL.HF Option module 1 hardware fault	Cause: Option slot 1 on the drive has indicated a hardware fault. Remedy: Replace the option module. Contact the supplier.
SL.nF Option module in option slot 1 has been removed	Cause: The option module in option slot 1 on the drive has been removed since the last power up. Remedy: Reinstall the module if removal was unintentional. Save parameters to acknowledge the removal.
SL.tO Option module watchdog function service error	Cause: The option module installed in Slot 1 has started the option watchdog function and then failed to service the watchdog correctly. Remedy: Check option module firmware. Replace option module if error persists.
So.St Soft start relay failed to close, soft start monitor failed	Cause: Soft start relay in the drive failed to close or the soft start monitoring circuit has failed. Remedy: Check drive internal hardware. Cycle power.
St.HF Hardware trip has occurred during last power down	Cause: Hardware trip (HF01 – HF19) has occurred and the drive has been power cycled. Remedy: Enter 1299 to Pr 00 or xx.000 to clear trip. Investigate the previous hardware fault code.
Sto No Safe Torque Off board installed	Cause: Safe Torque Off board not installed correctly. Remedy: Check Safe Torque Off board installation.
th Motor thermistor over-temperature	Cause: The motor thermistor connected to terminal 14 (digital input 5) on the control connections has indicated a motor over temperature. Remedy: Check motor cooling. Check load conditions. Verify thermistor connection and type.
th.br Brake resistor over temperature	Cause: The th.br trip is initiated if the hardware based braking resistor thermal monitoring is connected and the resistor overheats. Remedy: Check braking resistor sizing and duty cycle. Check wiring of thermal monitoring.
tH.Fb Internal thermistor has failed	Cause: Internal thermistor has failed. Remedy: Hardware fault; contact supplier/Hotline.
thS Motor thermistor short circuit	Cause: The motor thermistor connected to terminal 14 (digital input 5) on the control connections, is short circuit or low impedance (<50 Ω). Remedy: Check thermistor wiring for shorts. Replace motor thermistor.
tun.S Autotune test stopped before completion	Cause: The drive was prevented from completing an autotune test, because either the drive enable or the drive run signals were removed. Remedy: Ensure drive enable and run signals remain active during autotune.
tun.1 Autotune 1	Cause: The drive has tripped during a rotating autotune. The cause of the trip can be identified from the sub-trip number. Sub-trip Reason 2 The motor did not reach the required speed during rotating auto-tune or mechanical load measurement. Remedy: Refer to the Control User Guide. Check motor load and mechanical constraints.
tun.3 Autotune 3	Cause: RFC-A mode only. The drive has tripped during a rotating auto-tune or mechanical load measurement. Sub-trip Reason 1 Measured inertia has exceeded the parameter range during a mechanical load measurement. 3 The mechanical load test has been unable to identify the motor inertia. Remedy: Refer to the Control User Guide.
U.OI User OI ac	Cause: The U.OI trip is initiated if the output current of the drive exceeds the trip level set by User Over Current Trip Level. Remedy: Check load current. Adjust User Over Current Trip Level if appropriate. Refer to the Control User Guide.
U.S User Save error / not completed	Cause: The U.S trip indicates that an error has been detected in the user save parameters saved in non-volatile memory. Remedy: Attempt to save parameters again. Check memory status (perform a default reset if necessary).
UP.uS User Program trip	Cause: This trip can be initiated from within an onboard user program. Remedy: Check the onboard user program logic. Refer to the Control User Guide.
UPrG User Program	Cause: An error has been detected in the onboard user program image. Remedy: Reload the user program. Refer to the Control User Guide.
br.res Brake resistor overload	Cause: Braking Resistor Thermal Accumulator in the drive has reached 75.0 % of the value at which the drive will trip. Remedy: Refer to the Power Installation Guide. Reduce braking duty cycle.
OV.Ld Motor Protection Accumulator warning	Cause: Motor Protection Accumulator in the drive has reached 75.0 % of the value at which the drive will trip and the load on the drive is >100 %. Remedy: Reduce motor current (load). Refer to the Parameter Reference Guide.
d.OV.Ld Drive over temperature	Cause: Percentage Of Drive Thermal Trip Level in the drive is greater than 90 %. Remedy: Check drive cooling/fans. Refer to the Parameter Reference Guide.
tuning Autotune in progress	Cause: The autotune procedure has been initialized and an autotune in progress. Remedy: Wait for autotune to complete.
LS Limit switch active	Cause: Indicates that a limit switch is active and that is causing the motor to be stopped. Remedy: Check mechanical limit switches.
Lo.AC Low voltage mode	Cause: Drive is operating in Low Voltage Mode. Remedy: See Low AC Alarm in Control User Guide.
I.AC.Lt Current limit active	Cause: Drive output current has reached the limit. Remedy: See Current Limit Active in Control User Guide.
24.LoSt 24V backup not present	Cause: 24V backup supply is missing. Remedy: See 24V Alarm Loss Enable in the Control User Guide.

 

Frequently Asked Questions (FAQ)

Q: What is the difference between a Trip and a Warning on the HS30?

A: A Trip (Solid code) is a protective shutdown that stops the motor immediately. A Warning (Flashing code) indicates the drive is nearing a limit—such as br.res (Braking Resistor Overload)—but is still running while the condition persists.

Q: How do I reset a Unidrive HS30 fault?

A: After clearing the root cause (e.g., checking for short circuits or cooling issues), reset the drive via:

• Pressing the Red STOP/RESET button on the drive keypad.
• Cycling the Main Power (wait for the display to go completely dark before restarting).
• Triggering a Digital Input assigned to the “Reset” function (Parameter 08.023).
• Sending a reset command via Modbus RTU communication.

Q: What does “inh” mean on the display?

A: “inh” stands for Inhibit. This is not a fault. It means the Safe Torque Off (STO) terminal is not receiving 24V. The drive is healthy but is being prevented from running by an external safety circuit or E-stop switch.

Q: My HS30 shows “It.AC,” what should I do?

A: This stands for Motor Thermal Overload. Because high-speed motors often have less thermal mass, they can overheat quickly. Check if the motor cooling fan is working, if the motor rated current (Pr 05.007) is set correctly, or if the load has increased due to tool wear.

Q: Where is the trip history stored?

A: The trip history is stored in Menu 10. This log is non-volatile and survives power cycles. You can view the history via the keypad by scrolling through parameters 10.020 to 10.029.