Applicable Systems
VF-AS1
Symptoms
The VF-AS1 reports an encoder fault. The feedback signal from the motor encoder is abnormal or lost, disabling closed-loop control.
Possible Causes
- Encoder cable damaged or disconnected
- Encoder internal electronics failure
- Electrical noise interfering with the encoder signal lines
Troubleshooting Steps
- Step 1: Check the encoder cable connection at both the motor and drive ends
Cable is properly connected at both ends - Step 2: Inspect the encoder cable for physical damage or broken wires
Cable is intact with no broken conductors - Step 3: Verify the encoder signal with an oscilloscope for proper pulse output
Encoder signal is clean with correct pulse count
How to Reset
To reset: Restore the encoder signal, then reset the fault and restart.
Source: Toshiba VF-AS1 Inverter Manual, Toshiba Mitsubishi-Electric Industrial Systems
Category: PLC & VFD