Applicable Systems
EFC
FEX
FEI
HNC
Symptoms
Safe position increment exceeded. The safety system has detected that the position change between two safety cycles exceeds the configured safe position increment limit.
Possible Causes
- Motor moved more than the allowed increment between safety check cycles
- Encoder resolution too low for the configured increment check
- Safety cycle time too long, allowing excessive travel between checks
- External force moving the motor during safety monitoring
Troubleshooting Steps
- Step 1: Check the safe position increment parameter in IndraWorks AS
Increment value matches the safety assessment calculation - Step 2: Verify encoder resolution is adequate for the monitoring sensitivity
Encoder resolution provides sufficient position feedback granularity - Step 3: Review the safety cycle time setting
Cycle time is within the acceptable range for the application speed - Step 4: If the motor moved due to external force, address the mechanical cause
No uncontrolled external forces acting on the motor
How to Reset
1) Check safe position increment parameter. 2) Verify encoder resolution. 3) Review safety cycle time. 4) Address mechanical causes. Caution: Safe position increment is calculated during the safety assessment and must not be modified without recalculation.
Frequently Asked Questions
- Q: How is the safe position increment calculated?
It is based on the maximum allowed travel distance in one safety cycle (typically 2-7ms). Increment = maximum speed x safety cycle time x safety factor.
- Q: What happens when the increment is exceeded?
The safety system activates a safe stop. This typically indicates either an encoder problem or that the motor is moving faster than the safety assessment allows.
Source: Rexroth IndraDrive Safety Integrated Manual, Bosch Rexroth AG
Category: PLC & VFD