Applicable Systems
EFC
FEX
FEI
HNC
Symptoms
Encoder 2 signal amplitude error. The secondary encoder feedback signal amplitude is outside the acceptable range. The drive may continue with encoder 1 only or trip depending on configuration.
Possible Causes
- Encoder 2 cable length exceeds maximum (typically 50m for TTL, 100m for sin/cos)
- Encoder 2 connector resistance high due to corrosion
- Encoder 2 internal output stage weakening
- Signal conditioning circuit on drive fault
Troubleshooting Steps
- Step 1: Measure encoder 2 signal amplitude at the drive input terminals
Signal amplitude within specification for the encoder type - Step 2: Shorten encoder cable or use a signal repeater if length exceeds maximum
Signal amplitude recovers to acceptable levels - Step 3: Clean encoder 2 connector contacts with electronic contact cleaner
Contact resistance reduced; signal amplitude improves - Step 4: If amplitude is still low at the encoder output, replace encoder 2
New encoder produces full-amplitude signal
How to Reset
1) Check signal amplitude at drive input. 2) Reduce cable length or add repeater. 3) Clean connectors. 4) Replace encoder if needed.
Frequently Asked Questions
- Q: What is the difference between encoder 1 and encoder 2 on IndraDrive?
Encoder 1 is typically the motor-mounted feedback for speed/position. Encoder 2 is often a secondary feedback (e.g., linear scale on the load) for dual-loop position control.
- Q: Can I run with only encoder 1 if encoder 2 fails?
Yes, if the application allows single-loop control. Disable encoder 2 in the drive parameters and switch to single-loop mode. However, position accuracy may be reduced.
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Source: Rexroth IndraDrive HCS/HMS Fault Code List, Bosch Rexroth AG
Category: PLC & VFD
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