Video: What causes an HMI COM FAULT on an ATV61 or ATV71 series drive?


25 November 2022

What are some possible causes of SLF3 or HMI COM Fault on an ATV61 or ATV71 AC Drive.

Product Line:
ATV61 / ATV71 series drives

Where the HMI keypad is being used to control the start/stop of the drive and/or the speed reference: All models, All serial numbers.

Customer unable to find the answer in existing literature

HMI Com fault is caused when the HMI loses communication with the drive.   The HMI module of the ATV61/ATV71 series drives establishes a Modbus RTU connection at power up with the HMI being the Modbus Server.  This connection is separate from the Modbus/Canopen channel and is isolated.  This fault can only occur when the drive is configured to receive the start/stop control and/or the speed reference from the keypad.  

When this fault occurs, the most common causes are: 
- Someone accidently disconnected the cable from the drive or back of the HMI
- Enclosure Door was opened and connection to the back of the HMI Mount is loose or was disconnected.
- Check +10v to COM on the Control Terminals on the drive to ensure that nothing is pulling that down, particularly if the HMI remotely mounted more than 100ft from the drive.
- A failure of the HMI itself (part# VW3A1101)
- If the keypad is mounted remotely, the cable connecting it to the drive has failed. (VW3A1104RXX where XX = 10 for 1 meter cable, 30 for 3 meter, 50 for 5 meter or 100 for 10 meter)