SV0361 Pulsecoder Phase Error (Built-in) fault in Fanuc drive

SV0361 Pulsecoder Phase Error (Built-in) fault in Fanuc drive

Description

SV0361 is a logic error related to the internal signals of the built-in Pulsecoder. The encoder generates digital position signals. The drive monitors the phase relationship and transitions of these signals. SV0361 triggers if the drive detects an illegal transition pattern that indicates the encoder's internal electronics are malfunctioning. This is effectively a "Sanity Check" failure of the feedback device.

Cause

• Encoder Failure: The internal chip or optical sensor in the motor cap has failed.
• Cable Impedance: Using a shielded cable that is too long or has high capacitance can round off the square wave edges, confusing the phase detection logic.
• Vibration: Extreme shock loads can crack the glass disk or disrupt the read head.

Solution

1. Swap Motor: Because the error logic is internal to the encoder's processing chip, this is almost 100% a motor replacement scenario.
2. Check Cable Shield: Ensure the feedback cable is a twisted-pair shielded type and grounded correctly. Phase errors can sometimes be induced by strong EMI.
3. Cooling: If the motor is extremely hot, the encoder electronics may be thermally drifting.