Rexroth IndraDrive HCS Error Code F8042

Rexroth PLC & VFD Major Hardware

Model: IndraDrive HCS | Code: F8042

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

  1. Step 1: Measure encoder 2 signal amplitude at the drive input terminals
    Signal amplitude within specification for the encoder type
  2. Step 2: Shorten encoder cable or use a signal repeater if length exceeds maximum
    Signal amplitude recovers to acceptable levels
  3. Step 3: Clean encoder 2 connector contacts with electronic contact cleaner
    Contact resistance reduced; signal amplitude improves
  4. 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.

Related Rexroth Fault Codes

Source: Rexroth IndraDrive HCS/HMS Fault Code List, Bosch Rexroth AG

Category: PLC & VFD