FANUC System APC Alarm – Absolute Pulse Coder (APC) Alarm

Causes of the Alarm:

1. The battery is depleted, the encoder cable is shorted, open-circuited, or has been disconnected, or the axis disassembly signal is abnormal, etc.

2. Alarm codes 300 to 349 correspond to APC (Absolute Pulse Coder) alarms. You can refer to the specific alarm number and on-screen message for detailed information, as shown in the image.

3. After the fault is resolved, set the mechanical zero point:

    

   • Locate the mechanical zero point.

   • In parameter 1815 — APC, set APZ = 1.

   • (If the battery is replaced without powering off, the zero-point reset can be avoided.)

Common APC-Related Alarm Cases and Troubleshooting

SV0301 – APC Alarm: Communication Error

• Check the feedback cable for poor contact; replace the cable if needed.

• Inspect the servo drive control PCB; replace if necessary.

• Replace the pulse coder.

SV0306 – APC Alarm: Overflow Alarm

• Check that parameters No.2084 and No.2085 are correctly set.

• Replace the pulse coder.

SV0307 – APC Alarm: Excess Axis Movement

• Check whether the feedback cable is normal.

• Replace the cable if needed.

SV0360 – Pulse Coder Code Check Error (Built-in)

• Inspect the pulse coder for faults.

• Replace the pulse coder.

SV0364 – Software Phase Alarm (Built-in)

• Check the pulse coder.

• Replace the pulse coder.

• Check for electrical noise and ensure the feedback cable shielding is intact.

SV0366 – Pulse Loss Alarm (Built-in)

• Check shielding of the feedback cable; ensure there’s no interference.

• Replace the pulse coder.

SV0367 – Count Loss Alarm (Built-in)

• Verify feedback cable shielding and check for interference.

• Replace the pulse coder.

SV0368 – Serial Data Error (Built-in)

• Ensure proper feedback cable shielding.

• Replace the cable.

• Replace the pulse coder.

SV0369 – Serial Data Transmission Error (Built-in)

• Check feedback cable shielding and look for interference sources.

• Replace the cable.

• Replace the pulse coder.

SV0380 – Separate Detector LED Abnormal (External)

• Check whether the separated interface unit (SDU) powers on correctly.

• Replace the SDU if necessary.

SV0385 – Serial Data Error (External)

• Check if the SDU is functioning correctly.

• Inspect the feedback cable between the encoder scale and the SDU.

• Check the encoder scale itself.

SV0386 – Data Transmission Error (External)

• Verify the SDU is operating correctly.

• Inspect the feedback cable between the encoder scale and SDU.

• Check the encoder scale.