Rockwell Automation T7480 ICS Regent+Plus Guarded Analog Output Modules - Manual (Page 2)

Guarded Analog Output Modules (T7480)
2
Industrial Control Services
Module Operation
A block diagram of the Guarded analog output module is
shown in Figure 1.
The processor modules send triplicated write data commands
over the I/O Safetybus to the Guarded output module.
Onboard the Guarded output module the triplicated data are
routed to two independent voter and I/O Safetybus logic
sections. Each section independently votes the triplicated
data and drives one digital-to-analog (D/A) converter for each
of the six output channels.
Figure 1. Block Diagram of Guarded Analog Output Module.
For each output channel, one of the D/A converter output
signals is used for the actual analog output drive signal. The
other D/A converter output signal generates a redundant
reference output signal. When all circuits are operating
correctly each channel’s drive output and reference output
should be the same. These two signals are compared on the
module and must be the same in order for the module to
control the field outputs.