This event type is used to detect three types of encoder faults:
- Broken wire errors
- Illegal state errors
- Absolute encoder initialization errors
- Timeout errors
- Protocol errors
Broken wire errors are detected for either incremental or
absolute encoders whenever both differential inputs of any encoder
receiver (A, B, or Index) are at the same voltage level (i. e.,
whenever one or both inputs is disconnected from the encoders differential
transmitter). The EncoderTermination configuration of the encoder
input must be TRUE for correct detection of broken wires.
Illegal state errors occur whenever transitions are seen
on both A and B phases of an encoder input at the same time (e.g.
noise spikes).
There are two types of absolute encoder initialization errors:
Timeout errors and Protocol errors. Timeout errors occur
when an absolute encoder does not transmit absolute encoder data
within the timeout period starting at the transition of the interrogation
line (SEN line). Protocol errors are detected when serial
absolute data is sent during the timeout, but the data cannot be
interpreted by the XMP. Both error types result in an ENCODER_FAULT
event.
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