EL
ErrorLib
Brands
||
  1. Home
  2. Fanuc
  3. Alpha i series AC Servo Motor
  4. 304
About·Privacy·Terms

ErrorLib — Industrial Fault Code Library

Disclaimer: ErrorLib is an independent technical reference tool. While we aim for accuracy, always verify with the manufacturer’s official service manuals before performing maintenance on industrial equipment. ErrorLib is not affiliated with the brands listed.

304

Serial Pulse Coder Mispulse Alarm (PMAL)

Fanuc · Alpha i series AC Servo Motor

What does 304 mean?

A mispulse alarm (PMAL) was detected for the serial pulse coder, indicating that the coder is generating incorrect or spurious pulses. This typically points to an internal fault within the pulse coder.

Common Causes

  • Generation of mispulses by the serial pulse coder.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn the main power OFF.

  2. 2

    If this alarm recurs immediately when power is reapplied, replace the motor (which contains the pulse coder).

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

000Power-Down Required Parameter011Zero Feedrate Specified013Maximum Feedrate Zero
Source: Fanuc Alpha i series AC Servo Motor
Open Manual (Page 224)Search more codes in this manual