Rockwell Automation T8433 Trusted TMR Isolated 4-20 mA Analogue Input Module - 20 Channel - Manual (Page 22)

Trusted
TM
Module T8433
Issue 11 Apr 10 PD-T8433 22
3.2.6. Rack 6: DISCREP
Channel Description
1 Discrepancy status inputs 1 to 16
2 Discrepancy status inputs 17 to 32
3 Discrepancy status inputs 33 to 40
Table 12 Rack 6: DISCREP bit descriptions
Each of the words reports the discrepancy status of 16 input channels. The corresponding bit within
the word is set to ‘1’ when a discrepancy condition is detected on that input channel’s input state (rack
2). Note that as with the other channel status arrays, channels 21 through 40 are a redundant image
of 1 through 20.
NOTE: The maximum allowable discrepancy time, established by the Trusted TM TMR Processor, is set to 2000
ms by default. The T8433 slices may sometimes be discrepant for longer than this in detecting the open input
condition when field devices are disconnected, or when powering up with open inputs. This can lead to
erroneous discrepancy indications. Therefore, it is recommended to use a ‘discrepancy_val’ setting of 4000 ms
or greater in the ‘system.ini’ configuration for the TMR Processor. Refer to the Product Description for the TMR
Processor, PD-8082B, for more information on how to change this value.