Applicable Systems
EFC
FEX
FEI
HNC
Symptoms
Encoder-to-motor mechanical connection fault. The drive has detected that the encoder feedback does not match the expected motor behavior, indicating a mechanical coupling issue.
Possible Causes
- Encoder coupling loose, damaged, or broken
- Encoder mounted incorrectly (wrong position or alignment)
- Motor and encoder shaft sizes mismatched
- Coupling set screw loose or missing
Troubleshooting Steps
- Step 1: Inspect encoder coupling for looseness or damage
Coupling firmly attached; no play or damage visible - Step 2: Check coupling set screws and tighten to specification
All set screws properly torqued - Step 3: Verify encoder is mounted in the correct position per motor drawing
Encoder position matches motor specification - Step 4: Replace coupling if damaged or worn
New coupling provides solid mechanical connection
How to Reset
1) Inspect coupling. 2) Tighten set screws. 3) Verify mounting position. 4) Replace coupling if damaged. 5) Reset fault.
Frequently Asked Questions
- Q: How do I know if the encoder coupling is the problem?
If the motor runs but the encoder reading doesn't track motor speed correctly, or if there's a constant position offset, the coupling is likely the issue.
- Q: What type of coupling is used for encoders?
Most use a flexible coupling (bellows or disk type) that compensates for slight misalignment while transmitting torque without backlash.
Source: Rexroth IndraDrive HCS/HMS Fault Code List, Bosch Rexroth AG
Category: PLC & VFD