Chapter 2
Description
Rockwell Automation Publication ICSTT-RM451D-EN-P - March 2021
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connect the FPU to each of the HIU slices to control the LED status indicators
and monitor the Module removal switches.
The Module automatically monitors the output channel current and voltage to
determine the state of the output channel. The numerical output state and
line fault status are reported back to the application and are represented
below.
Table 1 Line Monitoring Fault Status
Description
Numerical Output State
Line Fault Status
Field Short Circuit
5
1
Output Energized (On)
4
0
No Load, Field Open
Circuit
3
1
Output De-energized (Off) 2
0
No Field Supply Voltage
1
1
It is recommended to fit a dummy load resistor to unused outputs so that a
current is drawn that exceeds the NO-LOAD threshold. This helps prevent the
Module from signaling a NO-LOAD fault.
The Output Module automatically performs local measurements of several
onboard signals that can be used for detailed troubleshooting and verification
of Module operating characteristics. Measurements are made within each
slice’s HIU and FIU.
Extensive diagnostics provide the automatic detection of Module faults. The
TMR architecture of the Output Module and the diagnostics performed verify
the validity of all critical circuits. Using the TMR architecture provides a Fault
Tolerant method to withstand the first fault occurrence on the Module and
continue normal output controls without interruption in the system or
process. Faults are reported to the user through the Healthy status indicators
on the Front Panel of the Module and through the information that is
reported to the TMR Processor. Under normal operations, all three Healthy
indicators are green. When a fault occurs, one of the Healthy indicators
flashes red. It is recommended that this condition is investigated and if the
cause is within the Module, it should be replaced.
Module replacement activities depend on the type of spare Module
configuration that is chosen when the system was configured and installed.
The Module may be configured with a dedicated Companion Slot or with a
SmartSlot for a spare replacement Module.
From the IMB to the field connector, the I/O Module contains extensive fault
detection and integrity testing. As an output device, 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.
Line Monitoring and Output
States
Housekeeping
Fault Detection/Testing
