Rockwell Automation T80020 Application Note Diagnostic Procedures - Manual (Page 65)

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AN-T80020 Diagnostics Procedure
Issue 12 Feb 11 AN-T80020 65
0x7000 Series Codes (Processor generated)
All 7000 series faults are created by the processor when it notes a problem on a module’s slice. The
I/O module relies on the processor to log these faults.
MP_CHAN_DISCREP_ERROR
0x70nn
Modules:All
Subcode:nn = input/output
channel (1-based)
8471: 0x01 to 0x20 (1 to 32)
8472: 0x01 to 0x10 (1 to 16)
Others: 0x01 to 0x28 (1 to 40) This fault indicates that the channel state or value reported by this slice
is discrepant with respect to the other two slices. The front panel
channel LED will not indicate the fault unless two or more slices receive
the same fault code. A channel discrepancy may be due to a faulty IO
channel on that slice or to field conditions.
For inputs, builds 37 and later detect discrepancy by actual reading, but
earlier builds detect by state. A common cause in earlier builds is
where one slice is on the other side of a state threshold to the other two
channels. This may lead to a slice discrepancy which will result in the
slice being set offline (0x7100)
For inputs from build 37, noisy signals and drifting calibration may
create discrepancies. The discrepancy thresholds may be increased in
the INI if precision is not necessary; see PD-8110B.
For outputs, discrepancies are still detected by state because the
states are more defined, e.g. short circuit, de-energised. A common
cause of output discrepancies is loads near the minimum current,
where one slice may be starved of current and reporting open circuit.
Consider adding resistors to increase the load, or change the no-load
threshold for the group. Collect similar loads on each group. See
TN20031 for 8461. Very noisy loads may also create discrepancies;
check for logged transitions in and out of fault states on that channel.
Check the channel conditions as above. If there is no external reason
for discrepancies, try a replacement module.
Action:Slice fault, channel fault, channel state = 15
MP_SLICE_DISCREP_ERROR
0x7100
Modules:All This fault indicates that this slice reported a slice state that is
discrepant with respect to the other two slices. An example would be
two slices in ACTIVE and one slice in STANDBY. A slice state
discrepancy is primarily due to a fault within the slice that either forced
or inhibited a state change.
This fault is almost always a secondary effect of a slice going offline.
Check the log history for the initial cause.
Action:Slice OFFLINE
MP_LRAM_ERROR
0x7200
Modules:All
This fault indicates an LRAM (Local RAM) test failure. The processor
occassionally transmits a command containing an ASCII test pattern
(which can often be seen near the beginning of logs). The I/O module
calculates a check word for the pattern which is verified by the
processor. The LRAM is a storage buffer in the I/O module which is
part of the interface with the processor.
The I/O module cannot detect external memory access faults and
therefore relies on the processor. Return the module for repair.
Action:Slice OFFLINE