Encoder 2
ABB · ACS880
What does 7391 mean?
A feedback fault has occurred with Encoder 2. This is identical in nature to the Encoder 1 fault but pertains to the second encoder feedback channel, leading to similar loss of accurate motor position/speed data. This can affect dual-feedback systems or applications requiring redundant speed/position control.
Common Causes
- Broken or damaged wiring in the Encoder 2 cable (e.g., open circuit on A/B/Z signals, short to ground, intermittent connection).
- Encoder 2 power supply failure (e.g., loss of 5VDC or 15VDC at the encoder).
- Loose or corroded connections at the drive's second encoder input terminals (e.g., X22, X23) or at the encoder itself.
- Incorrect encoder type or pulse count parameter settings (e.g., P22-01, P22-02) for the installed Encoder 2.
- Excessive electromagnetic interference (EMI) affecting signal integrity of Encoder 2, especially on unshielded cables.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Verify 5VDC or 15VDC power supply to Encoder 2 at its connector (e.g., pins 1 and 2) using a multimeter.
- 2
Check continuity of all signal wires (A, /A, B, /B, Z, /Z) from Encoder 2 to the drive's second input terminals (e.g., X22, X23).
- 3
Inspect all terminals at Encoder 2 and its corresponding drive input for looseness, corrosion, or signs of damage.
- 4
Confirm Encoder 2 parameters (e.g., P22-01 Encoder 2 type, P22-02 Pulses per revolution) are correctly configured.
- 5
Ensure Encoder 2 cable shielding is properly terminated and grounded at both the drive and motor end to mitigate EMI.