Cause : Defect in F-IO processing comes when cross checking and comparing the two monitoring channels, the drive detected a difference between parameters or results of the F-IO processing and initiated a STOP F. One of the monitoring functions no longer reliably functions - i.e. safe operation is no longer possible.

- check parameterization in the parameters involved and correct if required.
- ensure equality by copying the SI data to processor 2 and then carry out an acceptance test.