Applicable Systems
EFC
FEX
FEI
HNC
Symptoms
Negative position limit exceeded. The motor has moved beyond the configured negative software position limit. Motion in the negative direction is stopped.
Possible Causes
- Commanded position beyond the negative software limit
- Position feedback drift causing false limit indication
- Software limit set too close to the operating range
- Home position reference shifted
Troubleshooting Steps
- Step 1: Check the negative software position limit parameter
Limit value matches the application's mechanical travel range - Step 2: Verify the home position reference is correct
Home position matches the mechanical reference point - Step 3: Check position feedback for drift or offset
Position reading matches expected value at the home position - Step 4: If the limit was genuinely exceeded, review the motion profile
Motion commands stay within the configured software limits
How to Reset
1) Check software limit. 2) Verify home position. 3) Check position feedback. 4) Review motion profile. 5) Reset fault.
Frequently Asked Questions
- Q: How do I set up software limits?
Determine the mechanical travel range, set the positive and negative limits inside the mechanical end-stops (typically 1-2mm before), and ensure they are inside the safe position limits.
- Q: What if position drift causes false limit triggers?
Re-home the axis to re-establish the position reference. If drift recurs, investigate encoder coupling, mechanical backlash, or temperature effects on the measuring system.
Source: Rexroth IndraDrive HCS/HMS Fault Code List, Bosch Rexroth AG
Category: PLC & VFD