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ErrorLib — Industrial Fault Code Library

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SV0304

APC ALARM: PARITY ERROR

Fanuc · Alpha i Series Servo Amplifier

What does SV0304 mean?

A parity error was detected during data transfer from the absolute-position detector, making it impossible to obtain the correct machine position. This error points to a potential defect in the absolute-position detector, its cable, or the servo interface module.

Common Causes

  • Parity bit error in the data transmitted by the APC.
  • Corrupted data bits in the transmission stream.
  • Faulty APC encoder generating incorrect parity.
  • Environmental noise corrupting data during transfer.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Verify parity setting (even/odd) in CNC communication parameters.

  2. 2

    Measure APC encoder output for signal integrity and bit stability.

  3. 3

    Check APC encoder for loose internal connections.

  4. 4

    Shield communication cables to prevent external interference.

Browse all codes in this manual (101)
Verified technical data. Last updated: April 2026

Related Faults

0233Velocity Pulse Count Exceeded0243Position Pulse Count Exceeded0434Velocity Loop Integral Gain Overflow
Source: Fanuc Alpha i Series Servo Amplifier
Open Manual (Page 127)Search more codes in this manual