F108-91
Internal CPU fault
SEW Eurodrive · MOVIDRIVE MDX60B/61B Variable Speed Drive
What does F108-91 mean?
An internal fault has been detected within the CPU of the DCS..B option. This indicates a critical hardware or firmware issue with the processing unit.
Source: SEW Eurodrive MOVIDRIVE MDX60B/61B Variable Speed Drive
Open Manual (Page 209)