IDC B8961/B8962 Commutation Sensor Fault

The 0x0688 or 0x0288 or 0x0289 fault is displayed on the keypad as an Undefined Fault. This fault code will be at the bottom of the keypad display. When connected to the ServoTuner software, these come up as Commutation Sensor Fault errors.

This fault is related to the commutation hall effect sensors in the encoder of the motor, and the corresponding wiring in the feedback cable.

It can be caused by a failed hall effect sensor or a broken hall wire in the feedback cable.

This fault can also occur when noise is introduced on the hall-effect circuitry of the B8000 series amplifier. Ground loops, electrical noise, or bad cables can cause the faults. To eliminate the possibility of a ground loop, check
continuity between GND and COM on the drive. If they are making continuity or if there's low resistance between the points, this can be the source of the problem.  Make sure to disconnect any RS-232 connections to a PC or keypad. A common cause of this continuity can be the shield of the motor cable touching the shield of the encoder/hall cable. If this is the cause, it usually occurs where the leads exit the cable at the drive end.  Pull the shields back and use heat-shrink or electrical tape to isolate the shields from each other.  An additional recommendation is to follow the EMC Installation Guidelines given in Appendix B of the Installation Manual.