Siemens SINAMICS G120 F31118: Encoder 1: speed difference exceeds tolerance

Siemens SINAMICS Electrical Fault Drive

Model: G120/G120C | Code: F31118

Symptoms

Using HTL/TTL encoder, speed difference between multiple encoder sampling cycles exceeded P0492 value.

Possible Causes

  • Encoder cable broken or plug loose
  • Installation wiring non-compliant
  • Electromagnetic interference on encoder cable
  • Cable too long

Troubleshooting Steps

  • Check encoder cable for breaks or loose plugs
  • Verify drive and motor properly grounded, use 4-core cable (3 phase + PE)
  • Ensure encoder cable shield properly grounded
  • Keep encoder cable >20cm from power cables
  • Check encoder cable length against maximum for communication rate
  • Increase maximum speed difference per sampling cycle (P0492) if necessary
  • First commissioning with encoder: set P1300=0 (V/F mode), run at constant frequency, check r0061 feedback speed matches given frequency

How to Reset

Reset by: 1) Correct the fault condition. 2) Press RESET button or send reset command via communication. 3) Verify fault does not recur during operation.

Related Siemens SINAMICS Fault Codes

Source: Siemens SINAMICS G120 Common Faults Manual (ad.siemens.com.cn)

Category: Electrical