Rockwell Automation T80020 Application Note Diagnostic Procedures - Manual (Page 67)

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AN-T80020 Diagnostics Procedure
Issue 12 Feb 11 AN-T80020 67
MP_BIU_TRANSIENT_ERROR
0x7402
Modules:All This indicates a bus discrepancy due to an I/O module fault. It may also
be caused by expander module or bus faults.
Faults appearing on the same slice on several modules in a chassis
indicates expander module or bus faults.
If the fault appears on only one module, and it returns repeatedly after
pressing Reset, return the module for repair.
Action:Slice fault
MP_FCR_DECODE_ERROR
0x7403
Modules:All
This fault indicates that the processor detected a slice ID error. The
processor writes a different data pattern to each slice and verifies that
the slice returns its own data. Return the module for repair.
Action:Slice OFFLINE