Rockwell Automation T3411 ICS Regent Monitored Digital Input Modules - Manual (Page 8)

Monitored Digital Input Modules (T3411)
8
Industrial Control Services
Application
Simplex Configuration
Monitored digital input modules provide a suitable interface
to safety-critical input signals. The circuits in the monitored
digital input modules are automatically tested and
annunciated, providing a fail-safe interface to digital inputs.
This simplex input configuration is illustrated in Figure 3.
Figure 3. Single Monitored Digital Input Configuration.
Fault Tolerant Configurations
For fault tolerant applications, redundant monitored input
modules are used in a fault tolerant configuration. In one
configuration the redundant input modules are connected in
parallel to a single field input device as illustrated in Figure
4. If redundant field sensors are installed in the field, the
modules are connected so that each sensor connects to one of
the modules as illustrated in Figure 5. In these fault tolerant
configurations, each monitored digital input module is hot
replaceable. If a fault occurs on one module, it can be
removed and replaced while the system continues to correctly
sense the inputs from the remaining module(s).