Rockwell Automation T7480 ICS Regent+Plus Guarded Analog Output Modules - Manual (Page 7)

Guarded Analog Output Modules (T7480)
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Application
Guarded analog output modules are suited for high integrity
control of analog output devices. Guarded output modules can
be used for fail-safe or fault tolerant operation.
Fail-Safe Configuration
As shown in Figure 3, fail-safe configuration uses a single
Guarded module. In this configuration, the worst case failure
will cause the output to fail to the off state.
In a fail-safe configuration, a module failure and subsequent
removal of the module disables all of its outputs.
Figure 3. Fail-Safe Configuration.
Fault Tolerant Configuration
For fault tolerant operation, two Guarded modules are
connected in parallel as shown in Figure 4. In this
configuration, operation continues even if one module fails.
In the fault tolerant configuration, a failed module can be
removed and replaced without interrupting operation of the
loads.