Rockwell Automation T8472 Trusted TMR 120V ac Isolated Output Module - Manual (Page 10)

Trusted
TM
Module T8472
Issue 13 Sep 11 PD-T8472 10
1.8. Sequence of Events Characteristics
The module automatically measures the field voltage and current to determine the state of each output
channel. An event occurs when the output transitions from one state to another. When a channel
changes state, the on-board timer value is recorded. When the TMR Processor next reads data from
the output module, the channel state and real-time clock value are retrieved. The TMR Processor
uses this data to log the state change into the system Sequence of Events (SOE) log. The user may
configure each output to be included in the system SOE log.
Full details of SOE are contained in PD-T8013 SOE and Process Historian.
1.9. Output Switch Structure
The Digital Output Module provides a QUAD ELEMENT switch topology where each load is driven by a
total of four fully monitored, fail-safe (4 element) ‘high-side’ switches configured as a dual redundant
series / parallel combination. With this configuration a failed Switch Element (either failed open or
failed short circuited) can be isolated and switch channel functionality maintained.
The 16 output channels are configured as two groups of 8 each and each group has its own field
supply connections.
Group 1 Output Channels (Ch1 to Ch8) are physically resident on the FIU board.
Group 2 Output Channels (Ch9 to Ch16) are physically resident on the FTU board.
Due to the majority voting scheme incorporated on FIU-QA, QB, QC and QD voters, any single HIU
main slice A, B & C failure will not result in the loss of any Switch Element operation.