Cause : Fault in measuring channel for digital speed sensing using pulse encoder (active in all operating states)

1. Disturbances on encoder cables:

Faults on the encoder cables (transitions to 0 with a 1 signal or to 1 with a 0 signal) are signalled as a rotational direction change by the evaluation circuit. Frequent changes in rotational direction can occur only at speeds around 0.

The fault message is activated if 10 consecutive pulse encoder signal evaluations identify “direction of rotation change” at a speed of ≥ 48 rev/min and an EMF > threshold (see below).

2. Pulse encoder defective:

The fault message is activated if, at an EMF > threshold (see below) 10 consecutive pulse encoder signal evaluations identify “implausible characteristics” of these signals (i.e. frequent rotational direction changes, edges too close together, failure of an encoder cable or short circuit between two encoder cables).

Possible fault causes

♦ EMC-related interference on a pulse encoder signal (terminals 28 to 31)
♦ Pulse encoder defective
♦ Interruption in an encoder cable
♦ Short circuit between an encoder cable and the supply voltage or another encoder cable
♦ P110 or P111 is incorrectly set (resulting in incorrectly calculation of EMF)