Rockwell Automation T7454 ICS Regent+Plus AC Isolated Digital Output Module - Manual (Page 3)

(T7454) AC Isolated Digital Output Module
P D - 7 0 1 8 M a r - 0 6
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outputs, to operate load devices powered from isolated field
power supplies.
Each output is individually fused to protect the circuits from
short circuit conditions in output wiring and field devices.
Testing and Diagnostics
Each module’s voter circuits are periodically tested by the
processor modules. Discrepant data are sent through one of
three legs of the I/O Safetybus to determine whether the
module’s voter is able to outvote the incorrect data. A failure
to return the correct majority-voted result to the processors
produces an I/O module error indication at the processor
modules and a module fault indication at the I/O module.
Each type of module has a unique identification code that is
read by the controller. This code lets the controller know
which type of module is installed in each I/O chassis slot and
how to address that module and its points specifically. If a
module is removed, or is replaced with a module of a different
type, the processor modules will indicate an I/O module error.
Loopback logic tests periodically write data to the module and
then read it back to determine whether the module’s I/O bus
interface logic is functioning correctly.
Fuses are continually checked for continuity. Field power and
the minimum load (see Specifications, page 12) must be
connected to each output in order to detect a blown fuse.
Front Panel Indicators
The 110 VAC isolated digital output module is shown in
Figure 2. The front panel contains the active and fault status
indicators, shutdown indicator, and output status and blown
fuse indicators for each output circuit.
Active and Fault Status Indicators
These green and red LEDs indicate the overall health of the
module. During normal operation, the green ACTIVE
indicator flashes at the controller’s scan rate. If a module
fault is detected the red FAULT indicator turns on and the
green indicator turns off.