EL
ErrorLib
Brands
||
  1. Home
  2. Fanuc
  3. Alpha i Series Servo Amplifier
  4. Alarm 8
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.

Alarm 8

Separate Serial Pulse Coder Communication Alarm

Fanuc · Alpha i Series Servo Amplifier

What does Alarm 8 mean?

This alarm signifies incorrect serial communication with the separate serial pulse coder. It can be caused by noise (specifically if CRC or STBB occurs). If the alarm is issued continuously after power is turned on and noise measures are taken, the pulse coder, the amplifier's control board (α i series), or the pulse module (α i series) may be defective.

Common Causes

  • Communication error with the separate serial pulse coder (encoder).
  • The encoder is not sending data, or data is corrupted.
  • Incorrect communication settings (e.g., baud rate, address) for the encoder.
  • Cable fault or loose connection to the encoder.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check whether the cable connection for the separate serial pulse coder is correct and whether there is a line disconnection.

  2. 2

    If CRC or STBB occurs, take noise-preventive measures.

  3. 3

    If the alarm is always issued after power is turned on and noise measures have been taken, consider replacing the pulse coder, the control board of the amplifier (α i series), or the pulse module (α i series).

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 45)Search more codes in this manual