Rockwell Automation T80020 Application Note Diagnostic Procedures - Manual (Page 55)

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AN-T80020 Diagnostics Procedure
Issue 12 Feb 11 AN-T80020 55
0x6000 Series Codes (Output Field Interface Unit)
OFIU_GFSS_BIAS_FAULT
0x603n
Modules:Output (not 8442,72 or
80)
Subcode:n = output group
8471: n = 0 to 3
Others: n = 0 to 4 Detects a stuck bias signal in the Group Fail Safe Switch (GFSS). This
fault may also be caused by channel current noise, which may be
caused by poor zero volt referencing or nonlinear loads (the test is less
sensitive from TUV 3.5 firmware). For persistent faults, check the load
linearity and try a replacement module.
Action:Slice fault
OFIU_GFSS_EN_FAULT
0x604n
Modules:Output (not 8442,72 or
80)
Subcode:n = output group
8471: n = 0 to 3
Others: n = 0 to 4 Detects a stuck FETin the Group Fail Safe Switch (GFSS). This also
includes a stuck GFSS_BIAS_ENABLE in the owner slice, such that
the bias cannot be turned off. This fault may also be caused by channel
current noise, which may be caused by poor zero volt referencing or
nonlinear loads (the test is less sensitive from TUV 3.5 firmware). For
persistent faults, check the load linearity and try a replacement module.
Action:Slice fault
OFIU_STUCK_ON_FAULT
0x605n
Modules:Output (not 8480)
Subcode:
8471: n = output group 0 to 3
8472: n = channel (0 to F)
8442: n = output (0 to 5)
Others: n = output group 0 to 4 Checks for an output channel that is stuck ON, i.e the channel has
been commanded OFF and there is a problem with the load voltage or
load current that suggests the load may still be powered. This is a
critical fault for a safety related output that must be able to de-energise.
There are two main sets of fault conditions:
1) Output commanded off, but current AND voltage on output
2) Output commanded off, and channel is not off, the slice recently
changed state and another slice went offline.
See AN-80004 for details on channel state definitions.
This fault can be easily induced by shorting an output channel to
VFIELD. This has been observed in systems caused by corrosion in
junction boxes in the field, and with direct lamp test circuits.
The fault can also occur due to switching noise from other channels in
a group if the resulting current measurement noise is V NLTHRESH.
Ensure that outputs in each group have similar loads (do not mix heavy
and light loads in a group).
A low value of NLTHRESH will increase the test sensitivity because it is
used as the maximum allowed current. Check that the NLTHRESH
settings are appropriate (see TN20031 and AN-80004). A setting of 5 is
the recommended minimum. 3 is possible but significantly increases
the risk of these faults and shutdowns. 1 is below the measurement
resolution and impossible.
The 8472 test is a clearer indication of a module fault, due to different
circuitry. 8442 is similar.
Note that on 8442 firmware release 3.5 this error may occur with no
SOFTA present even if marked as absent in the INI; in this instance a
firmware upgrade is recommended.
Action:Slice OFFLINE, commonly resulting in a module shutdown.