Rockwell Automation T7404 ICS Regent+Plus AC Digital Input Module 110VAC - Manual (Page 5)

(T7404) AC Digital Input Module
P D - 7 0 1 3 M a r - 0 6
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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.
Field Status Indicators
Input status indicators are located on the logic-side (after the
signal conditioning and isolation). The field status indicators
are lit when current is flowing through the input.
Application
Simplex Configuration
Digital input modules provide a suitable interface to non-
critical input signals. Although many of the circuits in the
digital input modules are automatically tested and
annunciated, some logic circuits and all of the field-side
sensing circuits are simplex and non-tested. This simplex
input configuration is illustrated in Figure 3.
Figure 3. Simplex Digital Input Configuration.
Fault Tolerant Connection
For critical inputs, redundant input modules are used in a
2oo3 or 1oo2 fault tolerant configuration. In these
configurations the redundant input modules are connected to
single or multiple sensors. If redundant sensors are installed