Having trouble with a WEG CFW500 VFD? Learn how to identify, troubleshoot, and reset Fxxx fault codes, Axxx alarms, and CONF status errors safely.

The WEG CFW500 is a high-performance variable frequency drive (VFD) designed for applications requiring precise speed and torque control . It supports sensorless vector (VVW), closed-loop vector, permanent magnet motor control (VVW PM), and scalar (V/f) control, and features an integrated SoftPLC . Because of its advanced processing capabilities, the drive features a robust diagnostic and self-protection routine to safeguard the inverter hardware, connected motor, and power lines .

When the drive detects an anomaly, it classifies the event into one of two diagnostic categories on its LCD or LED keypad (HMI) :

• Alarms (Axxx): Operational warnings that indicate a parameter is running near a safety limit (such as motor temperature warning) . Alarms do not stop the drive, allowing you to address the issue while the motor continues to run . Active alarms are logged in Parameter P0048 .
• Faults (Fxxx): Critical errors that immediately disable the drive's output transistors, allowing the motor to coast to a stop . The drive locks into a safe state and cannot be restarted until the fault is resolved and reset . Active faults are logged in Parameter P0049 .

This technical guide explains how to read the CFW500's diagnostic codes, perform a safe system reset, and troubleshoot the most common trips.

WEG CFW500 Fault and Alarm Reference Table

Locate the specific Fxxx or Axxx code currently active on your HMI display to match the diagnostic reading to its physical cause.

WEG CFW500 Drive Fault Codes List

Alarm / Fault and Meaning	Cause and Remedy
A0046 Motor Overload Motor overload alarm.	Cause: Settings of parameters P0156, P0157, and P0158 are configured too low for the used motor. Overload on the motor shaft. Remedy: Verify if parameters P0156, P0157, and P0158 are configured correctly according to the motor's actual capacity. Inspect the motor shaft and machine for mechanical blocks.
A0047 IGBT Overload Overload alarm on the power pack with IGBTs.	Cause: Inverter output overcurrent condition. Remedy: Analyze operating load levels and duty cycles to lower active output current. Check for mechanical drag.
A0050 Power Module Overtemperature Overtemperature alarm from the power module temperature sensor (NTC).	Cause: High ambient temperature around the inverter (> 50 °C (> 122 °F)) and high output current. Blocked or defective cooling fan. Heatsink is dirty, preventing proper cooling airflow. Remedy: Inspect cooling fan operation and clean any dust or debris from heatsink fins. Improve room/enclosure ventilation as needed.
A0090 External Alarm External alarm via DIx (option "No External Alarm" in P026x).	Cause: Wiring on DI1 to DI8 inputs is open or has poor contact. Remedy: Inspect terminal connections for digital inputs DI1 through DI8. Secure loose terminals and ensure reliable contact switch states.
A0098 Interruption of Self-tuning It indicates interruption of self-tuning.	Cause: The drive was disabled via digital input DIx when self-tuning was run (parameter P0408). Remedy: Ensure the digital input assigned to keep the drive enabled remains active during the entire self-tuning routine execution.
A0128 Telegram Reception Timeout Alarm indicating a serial communication fault. It indicates the equipment stopped receiving valid serial telegrams for a period longer than the setting in P0314.	Cause: Broken communication cable, general installation grounding faults, or loose terminal contacts. The master controller is not polling the drive within the timeout window set in parameter P0314. Remedy: Verify serial communication cabling, connections, and grounding lines. Ensure the master's polling interval is shorter than parameter P0314, or disable this timeout check in parameter P0314.
A0133 No Supply on CAN Interface It indicates that the CAN interface has no supply between pins 1 and 5 of the connector.	Cause: Power supply cables are misconnected or inverted. Poor contact on the cable or connector of the CAN interface. Remedy: Measure if there is voltage within the allowed range between pins 1 and 5 of the CAN interface connector. Check terminal strip alignment and cable contact.
A0134 Bus Off Bus off error detected on the CAN interface.	Cause: Short circuit on the CAN circuit transmission cable. CAN cables are misconnected or inverted. Mismatched baud rates among network devices. Termination resistors with the right value were not installed correctly (should only be at the physical ends of the main bus). CAN network was improperly installed. Remedy: Check CAN high and low wires for short circuits or inverted signals. Match node baud rates across the network. Check termination resistor values and placement.
A0135 Node Guarding/ Heartbeat CANopen communication error control detected communication error using the guarding mechanism.	Cause: Mismatched message exchange times between the master and slave. Master controller is not sending guarding telegrams within the assigned interval. Transmission delays or signal loss on the communication line. Remedy: Check the times set on both master and slave. To prevent conflicts, configure the error detection time on the slave to be a multiple of the master's exchange interval. Verify guarding telegram transmission.
A0136 Idle Master Alarm indicates that the DeviceNet network master is in Idle mode.	Cause: The master operation switch or run-bit is in the IDLE state in the host software. Remedy: Configure the master switch or corresponding bit to RUN in the configuration word of the master software. Refer to specific master software documentation.
A0137 DeviceNet Connection Timeout Alarm that indicates that one or more DeviceNet connections timed out.	Cause: Problem with the network master status. Issues in the network installation, broken cable, or poor contact on the network connections/grounding. Remedy: Verify the DeviceNet master status. Check general cable routing, connection shield lines, and grounding terminals.
A0138 Profibus DP Interface in Clear Mode It indicates that the inverter received the command from the Profibus DP network master to go into clear mode.	Cause: The network master status is not in run mode. Remedy: Verify the network master status, making sure it is in execution mode (Run).
A0139 Offline Profibus DP Interface It indicates interruption in the communication between the Profibus DP network master and the inverter. The Profibus DP communication interface went into offline status.	Cause: The network master is not configured or operating normally. Short circuit or loose contact on the communication cables. Cables are misconnected or inverted. Improperly placed termination resistors (should only be installed at the physical ends of the main bus). Profibus DP network cable routing or grounding is inadequate. Remedy: Check the PLC state. Check general cable routing, connection shield lines, and grounding terminals. Refer to the Profibus DP communication manual.
A0140 Profibus DP Module Access Error It indicates error in the access to the Profibus DP communication module data.	Cause: The Profibus DP module is not seated properly in the slot. Hardware errors due to improper handling or installation of the accessory module. Remedy: Verify Profibus module mounting in slot. Replace communication module if handling errors damaged the pins.
A0148 Ethernet Interface Access Error Indicates error in data exchange between CFW500 frequency inverter and Ethernet module.	Cause: Ethernet module is not properly connected to the product. The drive firmware version does not support the module. Hardware errors caused by improper handling or installation of the accessory. Remedy: Ensure the Ethernet module is physically secure and correctly seated. Verify that the drive's firmware version is compatible with the module. Replace the card if the hardware is damaged.
A0149 Ethernet Offline Indicates communication failure between the slave and the network controller.	Cause: The network master is not configured or operating normally. Short-circuit or bad contact in the communication cables. General installation grounding/cable routing issues. Remedy: Check network configuration. Inspect the cabling and general installation routing for grounding integrity or line faults.
A0163 Signal Fault AIx 4..20 mA Analogue input signal AIx at 4 to 20 mA or 20 to 4 mA is below 2 mA.	Cause: Current signal on the analogue input AIx is interrupted or null. Parameterization error on analogue input AIx. Remedy: Check current loop wiring on analogue input AIx for breaks or open circuits. Verify terminal screw contacts and parameter configuration settings for AIx.
A0168 Speed Error too High Difference between Speed Reference and Effective Speed greater than the setting in P0360.	Cause: The inverter is operating in Torque Current Limitation mode. Remedy: Check if the motor is stalled or heavily overloaded. Verify load status. If appropriate, adjust torque current limits in P0360.
A0177 Fan Replacement Fan replacement alarm (P0045 > 50000 hours).	Cause: The heatsink fan maximum number of operating hours has been reached. Remedy: Perform preventive fan replacement maintenance.
A0700 Communication Fault with Remote HMI No communication with remote HMI, but there is no speed command or reference for this source.	Cause: HMI cable is disconnected. Communication interface with the HMI is incorrectly configured in parameter P0312. Remedy: Check parameter P0312 to verify that the HMI communication interface is configured correctly. Reconnect or replace the HMI serial cable.
A0702 Inverter Disabled This failure occurs when there is an active SoftPLC movement block (REF block) while the "General Enable" command is disabled.	Cause: The General Enable command for the drive is not active. Remedy: Check the drive control terminal states to ensure the General Enable input command is active.
A0704 Two Movem. Enabled It occurs when 2 or more SoftPLC movement blocks (REF Block) are enabled at the same time.	Cause: Logic block overlap in the user program. Remedy: Check the user’s SoftPLC program logic to ensure only one movement block is active at any given time.
A0706 Refer. Not Progr. SPLC This failure occurs when a SoftPLC movement block is enabled but the speed reference has not been programmed for the SoftPLC.	Cause: Speed reference is missing or incorrectly routed in the local or remote configuration (parameters P0221 and P0222). Remedy: Check and verify the speed reference configuration in parameters P0221 and P0222 (Local and Remote modes).
A0708 SPLC Application Stopped SoftPLC application not running.	Cause: SoftPLC Application is stopped (parameters set as: P1001 = 0 and P1000 = 3). SoftPLC application code is incompatible with the CFW500 firmware version. Remedy: Verify runtime parameters. Upload an application version compatible with the inverter's active firmware version.
A0710 SPLC Progr. Bigger than 8 KB This failure occurs when the user tries to download a SoftPLC program bigger than 8 Kb.	Cause: The program size of the SoftPLC logic exceeded 8 KBytes. Remedy: Check project size. Optimize and compress the SoftPLC code structure to fit within permitted memory limits.
A0750 Program AIx for Process Variable of Main PID Controller Alarm that indicates an analog input was not programmed for the process variable of the main PID controller.	Cause: Parameter P0231 or P0236 was not programmed for 5 or 6. Remedy: Configure parameter P0231 or P0236 to option 5 or 6 according to the PID loop feedback setup.
A0752 Program DIx for Automatic / Manual Selection of the Main PID Controller Alarm that indicates a digital input was not programmed for automatic / manual selection of the main PID controller.	Cause: Parameter P0263, P0264, P0265, or P0266 was not programmed for 20. Remedy: Set the assigned digital input parameter (P0263 to P0266) to 20 to enable automatic/manual control routing.
A0754 Program LOCAL Reference (P0221) for SoftPLC Alarm that indicates the origin of the speed reference in LOCAL mode was not programmed for SoftPLC.	Cause: The main PID controller is enabled (P1017 set to 1 or 2) and the CFW500 frequency inverter is running the motor in LOCAL mode, but parameter P0221 is not programmed for 7. Remedy: Set parameter P0221 to 7 if utilizing the PID controller in local mode.
A0756 Program REMOTE Reference (P0222) for SoftPLC Alarm that indicates the origin of the speed reference in REMOTE mode was not programmed for SoftPLC.	Cause: The main PID controller is enabled (P1017 set to 1 or 2) and the CFW500 frequency inverter is running the motor in REMOTE mode, but parameter P0222 is not programmed for 7. Remedy: Set parameter P0222 to 7 if utilizing the PID controller in remote mode.
A0758 Program Indirect Engineering Unit 4 (P0516) for Hz or rpm Alarm that indicates the parameter for engineering unit of the motor speed was not programmed for Hz or rpm.	Cause: Parameter P0516 was not programmed for 13 (Hz) or 3 (rpm). Remedy: Configure parameter P0516 to option 13 (Hz) or 3 (rpm) to match your application units.
A0760 Low Level of the Process Variable of the Main PID Controller Alarm that indicates the process variable of the main PID controller has a low value.	Cause: Parameter P1030 is programmed for 1, and the process variable value has dropped below the threshold in P1031 for the time programmed in P1032. Remedy: Verify the process feedback sensor. Adjust parameters P1031 (threshold) and P1032 (delay time) if necessary.
A0762 High Level in the Process Variable of the Main PID Controller Alarm that indicates the process variable of the main PID controller has a high value.	Cause: Parameter P1030 is programmed for 1, and the process variable value has exceeded the threshold in P1033 for the time programmed in P1034. Remedy: Check for high limits in the process line (overpressure, high flow, etc.). Verify parameters P1033 and P1034.
A0764 Frequency Inverter in Sleep Mode Alarm that indicates the CFW500 frequency inverter is in the sleep mode.	Cause: The main PID controller is active in automatic mode, and the motor speed remained below the speed programmed in P1036 for the duration set in P1037. Remedy: Informational alarm status indicating sleep mode has engaged. To adjust this behavior, modify parameters P1036 (sleep speed) or P1037 (sleep delay time).
A0766 Dry Pump Detected Alarm indicating a dry pump condition was detected for the pump driven by the inverter.	Cause: Parameter P1042 is programmed for 1, the motor speed is above the speed programmed in P1043, and the motor torque has remained below the value programmed in P1044 for the time programmed in P1045. Remedy: Verify the fluid flow to the pump and check for blockages or dry lines. Verify the parameter configurations for P1042, P1043, P1044, and P1045.
A0768 Broken Belt Detected Alarm indicating a broken belt condition was detected for the motor driven by the inverter.	Cause: Parameter P1046 is programmed for 1, the motor speed is above the speed programmed in P1047, and the motor torque has remained below the value programmed in P1048 for the time programmed in P1049. Remedy: Check the mechanical coupling belt/pulley state. Verify the parameter configurations for P1046, P1047, P1048, and P1049.
A0770 Filter Maintenance Alarm indicating the need to replace the system filter.	Cause: Parameter P1050 is programmed for 1, and the total motor operation time shown in P1052 is above the value programmed in P1051. Remedy: Perform scheduled maintenance to replace the system filter. Reset the elapsed timer if required.
A0780 Program AIx for Process Variable of the External PID Controller Alarm indicating that an analog input was not programmed for the process variable of the external PID controller.	Cause: Parameter P0231 or P0236 was not programmed for option 8. Remedy: Set parameter P0231 or P0236 to option 8 to correctly route the external PID process feedback.
A0782 Program DIx for Automatic / Manual Selection of the External PID Controller Alarm indicating that a digital input was not programmed for automatic / manual selection of the external PID controller.	Cause: Parameter P0263, P0264, P0265, or P0266 was not programmed for option 21. Remedy: Set the assigned digital input parameter (P0263 to P0266) to 21 to enable manual/automatic switching functions.
A0784 Program AOx for Output of the External PID Controller Alarm indicating that an analog output was not programmed for output of the external PID controller.	Cause: Parameter P0251 or P0254 was not programmed for option 16. Remedy: Configure parameter P0251 or P0254 to option 16 to set the analog output target.
A0786 Low Level of the Process Variable of the External PID Controller Alarm indicating that the process variable of the external PID controller has a low value.	Cause: Parameter P1075 is programmed for 1, and the process variable of the external PID controller remained below the value programmed in P1076 for the duration set in P1077. Remedy: Verify the process feedback loops and verify configurations in parameters P1075, P1076, and P1077.
A0788 High Level of the Process Variable of the External PID Controller Alarm indicating that the process variable of the external PID controller has a high value.	Cause: Parameter P1075 is programmed for 1, and the process variable of the external PID controller remained above the value programmed in P1078 for the duration set in P1079. Remedy: Verify process line sensors. Check parameter thresholds set in P1075, P1078, and P1079.
F0021 Undervoltage on the DC Link Undervoltage fault on the intermediate circuit.	Cause: Wrong voltage supply (comply with inverter rating plate and parameter P0296). Mains voltage dropped producing a DC Link voltage below the minimum value (monitored in P0004): Ud < 200 Vdc in 200-240 Vac (P0296 = 0). Ud < 360 Vdc in 380-480 Vac (P0296 = 1). Ud < 500 Vdc in 500-600 Vac (P0296 = 2). Phase fault on the input. Fault in the pre-charge circuit. Remedy: Check input mains voltages. Check terminal blocks and check for missing phases. Verify parameters in P0296.
F0022 Overvoltage on the DC Link Overvoltage fault on the intermediate circuit.	Cause: Wrong voltage supply (comply with inverter rating plate and parameter P0296). DC link voltage exceeded permissible limits (monitored in P0004): Ud > 410 Vdc in 200-240 Vac (P0296 = 0). Ud > 810 Vdc in 380-480 Vac (P0296 = 1). Ud > 1000 Vdc in 500-600 Vac (P0296 = 2). Load inertia is too high or deceleration ramp is too fast. Parameters P0151, P0153, or P0185 are set too high. Remedy: Verify incoming mains supply. Increase deceleration time. Adjust parameters P0151, P0153, or P0185.
F0031 Communication Fault with Plug-in Module Main control cannot establish a communication link with the plug-in module.	Cause: Plug-in module is damaged. Plug-in module is not properly connected/seated. Problem in the identification of the plug-in module (refer to P0027). Remedy: Check the physical fit and terminal pin contacts of the plug-in card. Replace the card if damaged. Verify identification parameter P0027.
F0032 Fault in the Plug-in Module Connection Plug-in Module was incorrectly disconnected with the VSD powered up.	Cause: Plug-In Module was unplugged while inverter power was active. Plug-In Module is damaged or not properly connected. Problem in module identification (refer to P0027). Remedy: Ensure drive power is isolated before disconnecting accessory cards. Inspect the plugin board pins and re-seat correctly.
F0033 Self-tuning Fault Stator resistance setting fault P0409.	Cause: Stator resistance value in parameter P0409 does not comply with the inverter power rating. Motor connection error. Connected motor power rating is too low or too high in relation to the inverter capacity. Remedy: Turn off the power supply and inspect all connections at the motor terminal box. Verify if stator resistance parameter P0409 and motor power ratings are configured correctly.
F0048 Overload on the IGBTs Overload fault on the power pack with IGBTs (3 s in 1.5xInom).	Cause: Inverter output overcurrent is greater than 2xInom. Remedy: Check active load levels to lower current spikes. Inspect system sizing.
F0051 IGBTs Overtemperature Overtemperature fault measured on the temperature sensor of the power pack.	Cause: High ambient temperature around the inverter (> 50 °C (> 122 °F)) and high output current. Blocked or defective cooling fan. Heatsink is dirty, preventing proper cooling airflow. Remedy: Ensure ambient room temperature is within limits. Clean heatsink fins and verify that the cooling fan is operating correctly.
F0068 Motor Overtemperature (dedicated input) Overtemperature fault measured on the motor temperature sensor (Triple PTC) via dedicated circuitry in the power scheme.	Cause: Overload on the motor shaft. High start/stop duty cycle. High ambient temperature around the motor. Loose contact or short circuit (3 k9 < RPTC < 0 k1). Motor thermistor is not installed. Motor shaft is stuck. Remedy: Check the motor shaft and driven load for mechanical blockages. Optimize duty cycles. Measure thermistor circuit resistances and secure connections.
F0070 Overcurrent/Short circuit Overcurrent or short-circuit on the output, DC Link, or braking resistor.	Cause: Short-circuit between two motor phases. Short-circuit of the rheostatic braking resistor connection cables. IGBTs module is short-circuited or damaged. Drive started with an acceleration ramp that is too short. Drive started with the motor already spinning without using the Flying Start function. Remedy: Verify motor winding and connection cables for phase-to-phase shorts. Increase the acceleration ramp time. Enable the Flying Start function if the motor is prone to rotating during startup.
F0072 Motor Overload Motor overload fault (60 s in 1.5xInom).	Cause: Parameters P0156, P0157, or P0158 are configured too low in relation to the motor's operating current. Overload on the motor shaft. Remedy: Verify motor nominal currents and check P0156, P0157, and P0158. Check mechanical load on shaft.
F0074 Ground Fault Ground overcurrent fault.	Cause: Short-circuit to the ground in one or more output phases. Motor cable capacitance is too large, resulting in current peaks at the output. Note: This failure may be disabled by setting bit 0 of parameter P0343 to 0. Remedy: Verify insulation of motor cables and motor winding. If cable capacitance is high, reduce cable length or add an output reactor.
F0076 Motor Connection Error This fault indicates the motor presents phase loss, imbalanced phase current, or is disconnected.	Cause: Motor wiring or connection error. Loss of motor connection with the drive or broken wire. Remedy: Verify output cabling loops and check motor terminal box contacts.
F0078 Motor Overtemperature Overtemperature fault measured on the motor temperature sensor (Triple PTC) via analog input AIx or digital input DIx.	Cause: Overload on the motor shaft. High start/stop duty cycle. High ambient temperature around the motor. Poor contact or short-circuit (3k9 < RPTC < 0k1). Motor thermistor is not installed. Motor shaft is stuck. Remedy: Check the motor shaft and driven load for mechanical blockages. Optimize duty cycles. Measure thermistor circuit resistances and secure connections.
F0079 Encoder Signal Fault Failure of absence of encoder signals.	Cause: Wiring between encoder and the accessory interface encoder is broken or interrupted. Defective encoder. Remedy: Check encoder cabling and connections. Swap encoder if defective.
F0080 CPU Fault (Watchdog) Fault related to the supervision algorithm of the inverter main CPU.	Cause: High electrical noise. Inverter firmware fault. Remedy: Verify cabinet grounding and shield terminations. Update firmware if required.
F0084 Auto-diagnosis Fault Fault related to the automatic identification algorithm of the inverter hardware and plug-in module.	Cause: Poor contact in the connection between the main control and the power pack. Hardware not compatible with the firmware version. Defect detected in the internal circuits of the inverter. Remedy: Verify board contacts inside the drive. Check firmware and hardware compatibility.
F0085 Plug-in Module Will not Start Failure in the initialization of the plug-in module.	Cause: Defect on the plug-in module. Poor contact on the connections of the plug-in module to the inverter. Plug-in module does not have firmware loaded. Remedy: Verify physical seat of the plug-in board. Check for firmware matching.
F0091 External Fault External fault via DIx ("No External Fault" in P026x).	Cause: Wiring on digital inputs DI1 through DI8 is open or has poor contact. Remedy: Verify external cabling loops to the assigned digital inputs. Tighten loose screw terminals and check contact switches.
F0150 Motor Overspeed Overspeed fault. It is activated when the real speed exceeds the value of P0134 x (100 % + P0132) for more than 20 ms.	Cause: Wrong settings of parameters P0161 and/or P0162. Problem with hoist-type loads (mechanical drag). Remedy: Adjust overspeed limit parameters P0161 and P0162. For lifting or hoist applications, verify brake coordination and torque limits.
F0151 Incomp. Main Sw Version Main firmware version is different from the plug-in firmware version.	Cause: Blank memory on plug-in module (first power-up). Data backup fault during power-down. Remedy: Synchronize the database of the control unit with the plugin card memory.
F0169 Speed Error too High Difference between Speed Reference and Effective Speed greater than the setting in P0360 for longer than P0361.	Cause: The inverter has operated in Torque Current Limitation mode for too long. Remedy: Check if the motor is stalled or heavily overloaded. Verify load status. If appropriate, adjust torque current limits in P0360 and verify parameter P0361.
F0179 Fan Low Speed Internal fan with speed (P0036) under 2/3 of rated fan speed.	Cause: Internal cooling fan failure. Remedy: Check for fan obstructions. Replace the defective cooling fan.
F0182 Pulse Feedback Fault Pulse feedback circuit fault of the output voltage.	Cause: Hardware identification fault (compare P0295 and P0296 to the inverter identification label). Inverter internal pulse feedback circuit fault. Note: This monitoring can be disabled in parameter P0397. Remedy: Verify parameters P0295/P0296 configurations match rating plate. Set P0397 to 0 to disable if required.
F0228 Telegram Reception Timeout Indicates fault in the serial communication. The equipment stopped receiving valid serial telegrams for a period longer than the setting in P0314.	Cause: Pulse feedback input circuit fault. Broken cable, general installation grounding faults, or loose terminal contacts. The master controller is not sending telegrams within the time window set in parameter P0314. Remedy: Check serial communication cables, connectors, and shield grounding lines. Ensure the master's polling interval is shorter than parameter P0314, or disable this timeout check in parameter P0314. Inspect the pulse feedback loop cabling.
F0233 No Supply on CAN Interface This failure indicates that the CAN interface has no supply between pins 1 and 5 of the connector.	Cause: Power supply cables are misconnected or inverted. Contact problems on the cable or connector of the CAN interface. Remedy: Measure if there is voltage within the allowed range between pins 1 and 5 of the CAN interface connector. Check terminal strip alignment and cable contact.
F0234 Bus Off Bus off error detected on the CAN interface.	Cause: Short circuit on the CAN circuit transmission cable. CAN cables are misconnected or inverted. Not all network devices are configured with the same communication baud rate. Termination resistors with the right specification were not installed correctly (should only be at the physical ends of the main bus). CAN network was improperly installed. Remedy: Check CAN high and low wires for short circuits or inverted signals. Match node baud rates across the network. Check termination resistor values and placement.
F0235 Node Guarding/ Heartbeat CANopen communication error control detected communication error using the guarding mechanism.	Cause: Mismatched message exchange times between the master and slave. Master controller is not sending guarding telegrams within the assigned interval. Transmission delays or signal loss on the communication line. Remedy: Check times configured on both master and slave. To prevent conflicts, set the slave's error detection time to be a multiple of the master's exchange interval. Verify guarding telegram transmission.
F0236 Idle Master Fault indicates that the DeviceNet network master is in Idle mode.	Cause: The master operation switch or run-bit is in the IDLE state in the host software. Remedy: Configure the master switch or corresponding bit to RUN in the configuration word of the master software. Refer to the documentation of the master device used.
F0237 DeviceNet Connection Timeout Fault that indicates that one or more DeviceNet connections timed out.	Cause: Problem with the network master status. Issues in the network installation, broken cable, or poor contact on the network connections/grounding. Remedy: Verify the DeviceNet master status. Check general cable routing, connection shield lines, and grounding terminals.
F0238 Profibus DP Interface in Clear Mode It indicates that the inverter received the command from the Profibus DP network master to go into clear mode.	Cause: The network master status is not in run mode. Remedy: Verify the network master status, making sure it is in execution mode (Run).
F0239 Profibus DP Interface Offline It indicates interruption in the communication between the Profibus DP network master and the inverter. The Profibus DP communication interface went into offline status.	Cause: The network master is not configured or operating normally. Short circuit or loose contact on the communication cables. Cables are misconnected or inverted. Improperly placed termination resistors (should only be installed at the physical ends of the main bus). Profibus DP network cable routing or grounding is inadequate. Remedy: Check the PLC state. Check general cable routing, connection shield lines, and grounding terminals. Refer to the Profibus DP communication manual.
F0240 Profibus DP Module Access Fault It indicates fault in the access to the Profibus DP communication module data.	Cause: The Profibus DP module is not seated properly in the slot. Hardware errors due to improper handling or installation of the accessory module. Remedy: Verify Profibus module mounting in slot. Replace communication module if handling errors damaged the pins.
F0700 Remote HMI Communication Fault No communication with remote HMI, but there is speed command or reference for this source.	Cause: HMI cable is disconnected. Communication interface with the HMI is incorrectly configured in parameter P0312. Remedy: Check parameter P0312 to verify that the HMI communication interface is configured correctly. Reconnect or replace the HMI serial cable.
F0701 Remote HMI Communication Fault No communication with the remote HMI; however, there is command or frequency reference for this source.	Cause: HMI cable is disconnected. Communication interface with the HMI is incorrectly configured in parameter P0312. Remedy: Check parameter P0312 to verify that the HMI communication interface is configured correctly. Reconnect or replace the HMI serial cable.
F0709 SPLC Application Stopped SoftPLC application not running.	Cause: SoftPLC Application is stopped (parameters set as: P1001 = 0 and P1000 = 3). SoftPLC application code is incompatible with the CFW500 firmware version. Remedy: Verify parameter configurations for P1000 and P1001. Upload a compatible version of the SoftPLC application.
F0710 Size of the SoftPLC Application The size of the SoftPLC user’s program exceeded the maximum memory capacity.	Cause: The program size of the SoftPLC logic is too large. The total size limit is 8 Kilobytes for V/f scalar control (P0202 = 0) or VVW control (P0202 = 5). For vector control (P0202 = 4), memory size is limited to 7 Kilobytes. Remedy: Check project size. Optimize and compress the SoftPLC code structure to fit within permitted memory limits.
F0711 Fault on SoftPLC Application Fault found in SoftPLC user’s program.	Cause: SoftPLC user’s program stored on flash memory is corrupted. Timeout during execution of SoftPLC scan cycle. Remedy: Reload the user program onto the flash memory. Optimize program execution routines to prevent scan cycle timeouts.
F0761 Low Level of the Process Variable of the Main PID Controller Fault that indicates the process variation of the main PID controller has a low value.	Cause: Parameter P1030 is programmed for 2, and the process variable value has dropped below the threshold in P1031 for the time programmed in P1032. Remedy: Verify the process feedback sensor. Adjust parameters P1031 (threshold) and P1032 (delay time) if necessary.
F0763 High Level in the Process Variable of the Main PID Controller Fault that indicates the process variation of the main PID controller has a high value.	Cause: Parameter P1030 is programmed for 2, and the process variable value has exceeded the threshold in P1033 for the time programmed in P1034. Remedy: Check for high limits in the process line (overpressure, high flow, etc.). Verify parameters P1033 and P1034.
F0767 Dry Pump Detected Fault that indicates the dry pump condition was detected for the pump driven by the inverter.	Cause: Parameter P1042 is programmed for 2, the motor speed is above the speed programmed in P1043, and the motor torque has remained below the value programmed in P1044 for the time programmed in P1045. Remedy: Verify the fluid flow to the pump and check for blockages or dry lines. Verify the parameter configurations for P1042, P1043, P1044, and P1045.
F0769 Broken Belt Detected Fault that indicates the broken belt condition was detected for the motor driven by the inverter.	Cause: Parameter P1046 is programmed for 2, the motor speed is above the speed programmed in P1047, and the motor torque has remained below the value programmed in P1048 for the time programmed in P1049. Remedy: Check the mechanical coupling belt/pulley state. Verify the parameter configurations for P1046, P1047, P1048, and P1049.
F0771 Filter Maintenance Fault that indicates the need of replacing the system filter.	Cause: Parameter P1050 is programmed for 2, and the total motor operation time shown in P1052 is above the value programmed in P1051. Remedy: Perform scheduled maintenance to replace the system filter. Reset the elapsed timer if required.
F0773 HVAC Plug-in Module not Detected Indicates to the user that the plug-in module HVAC was not detected.	Cause: The installed plug-in module does not match the plug-in module for the specific HVAC function. Remedy: Ensure the physical plug-in board matches the required HVAC application specifications. Check module slot fitment.
F0787 Low Level of the Process Variable of the External PID Controller Fault that indicates the feedback of the external PID controller has a low value.	Cause: Parameter P1075 is programmed for 2, and the process variable of the external PID controller remained below the value programmed in P1076 for the duration set in P1077. Remedy: Verify the process feedback loops and verify configurations in parameters P1075, P1076, and P1077.
F0789 High Level of the Process Variable of the External PID Controller Fault that indicates the feedback of the external PID controller has a high value.	Cause: Parameter P1075 is programmed for 2, and the process variable of the external PID controller remained above the value programmed in P1078 for the duration set in P1079. Remedy: Verify process line sensors. Check parameter thresholds set in P1075, P1078, and P1079.

Decoding the "CONF" Status Error

In addition to standard fault codes, the CFW500 may display a CONF (Configuration) status on the HMI screen, which prevents the drive from enabling the motor output (PWM) . This occurs when two or more parameters have conflicting settings .

To identify the conflict, check Parameter P0047 (CONF Status) . For example, if P0047 displays a code representing an incompatible digital input configuration, you will need to re-verify the digital input settings in parameters P0263 through P0268 before the drive can run .

How to Retrieve Fault History

If the drive has tripped and the fault has been cleared, you can retrieve the historic fault logs directly from the control keypad parameters to aid in diagnostics :

• Parameter P0050: Stores the code of the most recent fault (Last Fault) .
• Parameters P0051 to P0053: Log the sequence of previous faults .

Methods to Reset a WEG CFW500 Fault

Before executing any reset, ensure the root physical cause of the trip has been thoroughly investigated and resolved. The CFW500 supports five standard reset methods:

1. Power Cycle (Power-On Reset): Turn off the main AC input power. Safety Requirement: Wait at least 10 minutes to allow the internal DC-link capacitors to fully discharge to safe voltage levels before handling wiring or restoring power.
2. Keypad Reset: Press the red O/RESET key on the HMI .
3. Digital Input Reset: If one of the digital inputs (DI1 to DI8, depending on the expansion module) is configured for "Reset" via parameters P0263 to P0268, you can apply a transition signal to clear the fault .
4. Auto-Reset Parameter: Parameter P0206 can be set to automatically clear transient faults after a programmed delay time . This is best reserved for self-clearing, non-hazardous line anomalies.
5. Fieldbus/Ethernet Command: Send a "Fault Reset" command bit through your communication network (Modbus RTU, Ethernet/IP, Profinet, etc.) control word .

Most Common CFW500 Faults and Troubleshooting

The majority of field trips on the CFW500 are caused by a small group of standard faults:

1. F0071 (Output Overcurrent)

This code triggers when the output current exceeds the drive’s maximum safe operating limit . It is typically caused by a phase-to-phase short circuit in the motor windings, a ground fault in the motor cabling, or an acceleration ramp time that is too short for a high-inertia load .

• Diagnostic: Try increasing the acceleration ramp time (Parameter P0100) . If the fault persists, disconnect the motor from output terminals U, V, and W, and measure the motor's winding resistance and insulation to earth.

2. F0021 (Undervoltage) & F0022 (Overvoltage)

These faults indicate that the intermediate DC bus voltage has slipped out of its safe operating window :

• F0021 (Undervoltage): Triggered when the input supply voltage sags below the minimum allowed limit . Verify the stability of the utility supply lines and inspect the input contactor .
• F0022 (Overvoltage): Occurs when the motor regenerates kinetic energy back to the drive during rapid deceleration . Try increasing the deceleration ramp time (Parameter P0101) or add a dynamic braking resistor if the application requires fast stops .

3. F0072 (Motor Overload)

This thermal trip indicates the motor has operated at currents higher than its nominal rating for too long, heating the windings .

• Diagnostic: Ensure that Parameter P0401 (Motor Rated Current) is configured to match the physical motor's nameplate rating . Inspect the motor shaft and driven load for mechanical binding, friction, or overload conditions .

4. F0006 (Input Voltage Imbalance or Phase Loss)

F0006 is triggered if the drive detects an input phase loss or if the voltage imbalance between the incoming phases exceeds 5% .

• Diagnostic: Use a digital multimeter to measure the AC line voltage across phases L1-L2, L2-L3, and L1-L3. Check for open fuses or tripped circuit breakers upstream.

Best Practices to Minimize CFW500 Faults

Implementing basic preventive practices helps ensure consistent operations and prevents premature component failure:

• Monitor Internal Temperatures: Check Parameter P0030 (Heatsink Temperature) to monitor thermal dissipation . If temperatures run high, check that the cooling fan is running properly and clean any dust or oil mist from the heatsink fins .
• Secure Grounding and Cabling: Ensure the motor cable shielding is grounded correctly at both ends to reduce electromagnetic noise . This prevents false feedback trips in the control and encoder circuits.
• Keep Up-To-Date Parameter Backups: The CFW500's optional flash memory modules or WPS software can be used to store parameter backups . Keeping a verified backup of your configurations ensures quick recovery times in the event of hardware replacements.

By understanding what the CFW500 is reporting through its diagnostic registers and maintaining clean, well-ventilated operating conditions, you can optimize system uptime and reliability.