A practical guide to diagnosing, troubleshooting, and resetting Fxxx faults and Axxx alarms on the WEG CFW100 G2 micro variable speed drive.

The WEG CFW100 G2 (Generation 2) is a highly compact micro variable frequency drive (VFD) designed for small machines and space-constrained control panels. Despite its small physical footprint, this drive features advanced control options like Vector (VVW) and Scalar (V/f) modes, a built-in SoftPLC, and a comprehensive protective system designed to monitor electrical and thermal parameters in real-time.

To keep your equipment safe, the CFW100 G2 categorizes potential issues into two distinct types of display codes:

• Alarms (Axxx): Warnings indicating that the drive is operating in a critical condition (such as motor overload). Alarms do not stop the motor, allowing you to resolve the situation before a hard trip occurs.
• Faults (Fxxx): Severe errors that immediately shut down the output transistors (IGBTs), allowing the motor to coast to a stop. The drive will lock and cannot be restarted until the fault is resolved and cleared.

This troubleshooting guide covers how to read these status codes, perform safe resets, and troubleshoot common issues seen in the field.

WEG CFW100 G2 Fault Codes Reference Table

Refer to your specific fault and alarm code lists to cross-reference the active EXX or FXX code displayed on the HMI. Finding the exact code will point you directly to the affected circuit or parameter.

WEG CFW100 G2 drive fault codes list

Fault / Alarm and Meaning	Cause and Remedy
A046 Motor Overload Motor overload alarm.	Cause: Settings of P156 are configured too low for the used motor. Overload on the motor shaft. Remedy: Verify if the overload protection parameter P156 matches the connected motor's ratings. Inspect the motor shaft and driven machinery for mechanical loads or blockages.
A050 Power Module Overtemperature Overtemperature alarm from the power module temperature sensor (NTC).	Cause: High temperature at the IGBTs (P030 > 110 °C). High ambient temperature around the inverter (> 50 °C (> 122 °F)) and high output current. Blocked or defective cooling fan. Heatsink is dirty, preventing proper airflow. Remedy: Check the active operating temperature via parameter P030. Ensure surrounding cabinet ventilation is sufficient. Inspect and clean any dust or blockages from the heatsink fins. Verify the operation of the cooling fan.
A090 External Alarm External alarm via DIx (option “No External Alarm” in P26x).	Cause: Wiring on DI1 to DI4 inputs is open or has poor contact. Remedy: Inspect connection terminals for digital inputs DI1 through DI4. Tighten any loose screws and ensure clean wire contact on the terminal strip.
A128 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 P314.	Cause: Issues in the network installation, broken cable, or poor contact on the network connections/grounding. The master controller is not sending telegrams within the time window set in parameter P314. Remedy: Check communication cable paths, shield grounding, and terminal blocks. Ensure the polling rate of the master controller is faster than the timeout set in P314. Alternatively, disable this timeout function by adjusting parameter P314.
A133 No power supply on the CAN interface It indicates that the CAN interface has no power 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 the voltage on the CAN interface connector to verify it falls within the permitted range between pins 1 and 5. Ensure external power lines are secure and correctly polarized.
A134 Bus Off Buss 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. Improperly placed termination resistors (should only be installed at the physical ends of the main bus). Incorrectly installed CAN network. Remedy: Check CAN high and low wires for short circuits or inverted lines. Verify that all nodes on the network are configured with the same communication baud rate. Check termination resistor values and placement.
A135 Node Guarding / Heartbeat CANopen communication error control detected a communication error using the guarding mechanism.	Cause: Mismatched message exchange times between the master and slave. Master controller is not sending the guarding telegrams within the assigned interval. Transmission delays or signal loss on the communication line. Remedy: Check the times set on both the master and slave nodes. To prevent delay conflicts, configure the error detection time on the slave to be a multiple of the master's exchange interval. Verify the master's active polling state.
A163 Signal Fault AI1 Analogue input signal AI1 at 4 to 20 mA or 20 to 4 mA is below 4 mA.	Cause: Broken analogue input 1 cable. Poor contact at the signal connection on the terminals. Remedy: Verify loop integrity for analog input 1. Inspect wiring pathways and ensure firm contact at the screw terminals.
A700 Remote HMI Communication Fault No communication with remote HMI, but there is an active frequency command or reference assigned to this source.	Cause: HMI cable is disconnected. Communication interface with the HMI is incorrectly configured. Remedy: Check parameter P312 to verify that the HMI communication interface is configured correctly. Reconnect or replace the HMI serial cable.
A702 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.
A704 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.
A706 Refer. Nao 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 configuration. Remedy: Check and verify the speed reference configuration in parameters P221 and P222 (Local and Remote modes).
A712 SPLC protected against copy It occurs when there is an attempt to copy a copy-protected SoftPLC application.	Cause: Attempting to copy a WLP application protected with "never permit copies" rules. Attempting to copy a WLP application protected with "no permission to copy from a copy" rules. Remedy: Verify the copyright and permission settings of the WLP application you are trying to manage.
F021 Undervoltage on the DC Link Undervoltage fault on the intermediate circuit.	Cause: Incorrect voltage supply. Input mains supply voltage is too low, producing a DC bus voltage below the minimum value (monitored in P0004): Ud < 200 Vdc in 200 / 240 Vac models. Line phase fault at the input. Pre-charge circuit fault. Remedy: Ensure the supply voltage matches the specifications listed on the inverter's rating label and is correctly set in parameter P296. Check the line phases for any missing connections or drops. Verify pre-charge circuit components are functional.
F022 Overvoltage on the DC Link Overvoltage fault on the intermediate circuit.	Cause: Wrong voltage supply. Check if the voltage complies with the parameters on the inverter rating label and parameter P296. Mains supply voltage is too high, producing a DC bus voltage above the maximum permitted value (monitored in P0004): Ud > 410 Vdc in 200 / 240 Vac models. Load inertia is too high or the deceleration ramp is set too fast. Parameter P151 setting is too high. Remedy: Verify incoming mains power supply match to rating parameters. Adjust deceleration ramp to be slower, or reduce parameter P151 setting. If necessary, consider dynamic braking options.
F033 VVW Self-tuning Fault Stator resistance setting fault P409.	Cause: Stator resistance value in parameter P409 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 the stator resistance parameter P409 and motor power parameters are correctly scaled.
F051 IGBTs Overtemperatures Overtemperature fault measured on the temperature sensor of the power pack.	Cause: High temperature detected at the IGBT modules (P030 > 120 °C). 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: Check the current temperature in parameter P030. Improve airflow around the drive or lower ambient room temperature. Clear any dust or debris build-up from the heatsink fins. Verify fan operation.
F070 Overcurrent/Shortcircuit Overcurrent or short-circuit on the output, DC link, or braking resistor.	Cause: Short-circuit between two motor phases. IGBT 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.
F072 Motor Overload Motor overload fault (60 s in 1.5xInom).	Cause: Parameter P156 setting is configured too low in relation to the motor's nominal operating current. Overload on the motor shaft. Remedy: Check and adjust the motor nominal current value in parameter P156. Check the motor shaft and driven load for mechanical blockages or excessive friction.
F080 CPU Fault (Watchdog) Fault related to the supervision algorithm of the inverter main CPU.	Cause: High electrical noise. Inverter firmware fault. Remedy: Inspect the installation grounding and shield connections to mitigate electrical noise. Update the control unit firmware if the issue is recurring.
F081 Fault on the Save User function Fault in the attempt to save the User parameter table.	Cause: Attempted to save (via parameter P204 = 9) more than 32 parameters with values different from the factory default. The Save User function is currently blocked in the firmware. Remedy: Limit custom user parameters with non-default values to 32 items or less. Check parameter block settings.
F082 Fault in the Copy Function (MMF) Fault in the copy of parameters.	Cause: Attempted to copy parameters from a Flash Memory Module with a different software version than the inverter. Remedy: Ensure software and firmware version compatibility between the Flash Memory Module and the target drive control unit.
F084 Auto-diagnosis Fault Fault related to the automatic identification algorithm of the inverter hardware.	Cause: Poor contact in the connection bridge between the main control board and the power pack. Hardware components are incompatible with the firmware version. Defect detected in the internal circuits of the inverter. Remedy: Check the connection and alignment of the boards inside the drive. Ensure firmware compatibility. Contact technical support if an internal hardware defect is suspected.
F091 External Fault External fault via DIx (“No External Fault” in P26x).	Cause: Wiring on digital inputs DI1 through DI4 is open or has poor contact. Remedy: Verify external cabling loops to the assigned digital inputs. Tighten loose screw terminals and check contact switches.
F228 Timeout in receipt of telegrams Indicates a fault in the serial communication. The equipment stopped receiving valid serial telegrams for a period longer than the setting in P314.	Cause: Issues in the network installation, broken cable, or poor contact on the network connections/grounding. The master controller is not sending telegrams within the time window set in parameter P314. Remedy: Check communication cable paths, shield grounding, and terminal blocks. Ensure the polling rate of the master controller is faster than the timeout set in P314. Alternatively, disable this timeout function by adjusting parameter P314.
F233 No power supply on the CAN interface It indicates that the CAN interface has no power 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 the voltage on the CAN interface connector to verify it falls within the permitted range between pins 1 and 5. Ensure external power lines are secure and correctly polarized.
F234 Bus Off Buss 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. Improperly placed termination resistors (should only be installed at the physical ends of the main bus). Incorrectly installed CAN network. Remedy: Check CAN high and low wires for short circuits or inverted lines. Verify that all nodes on the network are configured with the same communication baud rate. Check termination resistor values and placement.
F235 Node Guarding / Heartbeat CANopen communication error control detected a communication error using the guarding mechanism.	Cause: Mismatched message exchange times between the master and slave. Master controller is not sending the guarding telegrams within the assigned interval. Transmission delays or signal loss on the communication line. Remedy: Check the times set on both the master and slave nodes. To prevent delay conflicts, configure the error detection time on the slave to be a multiple of the master's exchange interval. Verify the master's active polling state.
F701 Remote HMI communication fault No communication with the remote HMI; however, there is an active command or frequency reference assigned to this source.	Cause: HMI cable is disconnected. Communication interface with the HMI is incorrectly configured in parameter P312. Remedy: Check parameter P312 to verify that the HMI communication interface is configured correctly. Reconnect or replace the HMI serial cable.
F710 SPLC Progr. bigger than 5 KB SoftPLC program memory size fault.	Cause: The size of the SoftPLC program exceeded 5 KBytes. Remedy: Verify the code size inside the user application logic. Optimize the SoftPLC program blocks to fit within the 5 KB memory capacity.
F711 The upload of the SoftPLC application failed The upload or the SoftPLC application failed.	Cause: The CPU failed to boot the SoftPLC. An incompatible application was uploaded (via parameter P900 = 2) and the run command was given (via parameter P901 = 0). Remedy: Verify application configuration and compatibility. Check parameter settings for P900 and P901. Attempt a fresh upload.

How to Safely Reset a WEG CFW100 G2 Fault

Once you have identified the fault code and successfully resolved the root cause, you must manually or programmatically reset the drive to clear the trip state. The CFW100 G2 supports four primary reset methods:

1. Power Cycle (Power-On Reset): Disconnect the main AC power supply to the drive. Safety Warning: Wait at least 10 minutes to allow the internal DC bus capacitors to discharge to safe levels before handling any wiring or restoring power.
2. HMI Reset Button: Press the red O/RESET key on the integrated graphic keypad of the drive.
3. Digital Input (DI) Reset: If one of the digital inputs (DI1 to DI4 on the base or expansion modules) is configured for "Reset" (Parameter P263 to P266), pulse that input to clear the fault.
4. Auto-Reset Parameter: You can configure the drive to automatically clear transient faults after a programmed delay time using parameter P206. This should be programmed carefully to avoid forcing repeated restarts on hard electrical faults.

Most Common CFW100 G2 Faults and Quick Diagnostics

While the full diagnostics list covers many scenarios, the majority of industrial trip events on micro drives fall into a few categories:

1. F070 (Overcurrent / Short Circuit)

This trip occurs when the drive detects output current exceeding its peak rating. It is commonly caused by a phase-to-phase short circuit in the motor wiring, a ground fault, or a sudden mechanical jam on the load. Before resetting, check the motor cables for insulation degradation and verify the motor rotates freely.

2. F021 & F022 (DC Link Undervoltage and Overvoltage)

These codes indicate issues within the drive's intermediate DC link circuit:

• F021 (Undervoltage): Often caused by an unstable main supply, temporary power sag, or incoming phase loss. Verify that the incoming line voltage matches the value set in parameter P296.
• F022 (Overvoltage): Usually triggered by regenerative feedback from the load when the deceleration ramp is too short. Try increasing the deceleration time parameters to let the load coast down more slowly.

3. F072 (Motor Overload)

The CFW100 G2 utilizes built-in software curves to simulate motor heating based on run times and operating currents. If the motor operates at high torque at low speeds, it lacks cooling from its shaft-driven fan, triggering F072. Ensure the motor is not mechanically overloaded and check that parameter P401 (Motor Rated Current) is set accurately to match the motor's nameplate.

Best Practices to Avoid Drive Trips

Micro drives like the CFW100 G2 are often mounted inside small, tightly packed enclosures where environmental control is crucial. Follow these practices to minimize trips:

• Monitor Ambient Temperatures: Small enclosures can trap heat quickly. Ensure the cooling vents on the CFW100 G2 remain clear and check that any enclosure exhaust fans are operating properly.
• Check Terminal Connections: Regularly check that the power input (L/N or L1/L2/L3) and motor output (U/V/W) terminals are tightened to correct torque specifications. Loose terminal screws can cause voltage drops and phase faults.
• Match Parameter Settings with the Nameplate: Ensure basic motor parameters—such as rated current, frequency, and nominal speed—are entered correctly into the drive during commissioning to avoid premature overload trips.

Understanding these protective functions and maintaining clean operating conditions will ensure your WEG CFW100 G2 runs reliably and minimizes production downtime.