Cause : reference position invalid comes when the transferred reference position is invalid due to the directly transfer the reference position not possible.

Message value (r9749, interpret decimal):
1: It is not possible to directly transfer the reference position (p9573=89).
2: It is not possible to transfer the reference into the motion.- unpark axis/encoder.

- acknowledge encoder fault
- de-activate gearbox stage switchover.
- when referencing via the Safety Control Channel (SCC), enable the function "Referencing via SCC" (p9501.27/9301.27).