Serial Pulse Coder is Abnormal
Fanuc · Series 20 CNC
What does 351 mean?
Similar to Alarm 350, this alarm indicates an abnormal condition or communication error specifically related to a serial pulse coder (encoder) on the Fanuc Series 20 CNC. It signifies a problem with the digital data transfer from the encoder to the servo system.
Common Causes
- Loose or damaged serial communication cable between the pulse coder and the servo amplifier.
- Electrical noise interfering with the serial data transmission.
- Malfunction of the serial pulse coder itself.
- Faulty serial interface on the servo amplifier.
- Incorrect parameter settings for the serial pulse coder.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Inspect the serial pulse coder cable for physical damage, loose connections, or improper shielding.
- 2
Verify proper termination of the serial communication line if applicable.
- 3
Check for sources of electromagnetic interference (EMI) near the cable runs and ensure proper grounding.
- 4
Examine diagnostic data related to the serial pulse coder for specific error sub-codes or communication status.
- 5
Temporarily swap the suspected pulse coder or servo amplifier with a known good one if feasible to isolate the fault.