Rockwell Automation T8448 Trusted TMR Zone Interface Module - 40 Channel - Manual (Page 12)

Trusted
TM
Module T8448
Issue 14 Apr 10 PD-T8448 12
1.6. Housekeeping
The Zone Interface Module automatically performs local measurements of several on-board signals
that can be used for detailed troubleshooting and verification of module operating characteristics.
Measurements are made within each slice’s HIU and FIU.
1.7. Fault Detection and Testing
From the IMB to the field connector, the I/O module contains extensive fault detection and integrity
testing. Most testing is performed in a non-interfering mode. Data input from the IMB is stored in
redundant error-correcting RAM on each slice portion of the HIU. Received data is voted on by each
slice. All data transmissions include a confirmation response from the receiver.
Periodically, the TMR Processor commands the onboard Digital Signal Processors (DSPs) to perform
a Safety Layer Test. The SLT results in the DSP verifying with the TMR Processor its ability to process
data with integrity. In addition, the DSP uses Cyclical Redundancy Checks (CRC) to verify the
variables and configuration stored in Flash memory.
Between the HIU and FIU are a series of optically isolated links for data and power. The data link is
synchronized and monitored for variance. Both FIU and HIU have onboard temperature sensors to
characterize temperature-related problems. Each FIU is also fitted with a condensation sensor.
The power supplies for both the HIU and FIU boards are redundant, fully instrumented and testable.
Together these assemblies form a Power Integrity Sub System.
1.8. Sequence of Events Characteristics
The module automatically measures the field voltage and current to determine the state of each
channel. An event occurs when the channel 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 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 channel to be included in the system SOE log. Full details of SOE are contained in PD-8013
Trusted
TM SOE and Process Historian.