Rockwell Automation T7480 ICS Regent+Plus Guarded Analog Output Modules - Manual (Page 9)

Guarded Analog Output Modules (T7480)
P D - 7 0 2 6 M a r - 0 6
9
Each time the single module enters the standby mode all six
of the output channels are taken off line and the field signals
become 0 mA. When the module switches back to the control
mode the field signals return to their controlled values. This
causes the output loads that have healthy wiring connections
to experience an output signal that toggles between 0 mA and
their controlled values which often produces undesirable
effects. To avoid this, you should monitor the fault status
system control relay for the output module in your application
program and use it to set all of the analog output channels to
zero. Turning all of the outputs off will often be safer than
letting them toggle between 0 mA and a controlled value.
Dual Guarded Module Configuration
In a dual module configuration the two modules will switch
back and forth between control and standby modes. The ON
status LED will appear to “ping-pong” back and forth between
the two modules about every one or two seconds. This will
continue until the open circuit field wiring is corrected.
During this time the module FAULT status LED will also be
on for each of the modules and the system will report a fault
for both modules.
While in this mode the remaining output loads that have
healthy field wiring connections should continue to be
controlled correctly because one of the two modules is always
in the control mode.
Fault Mode Jumper
The fault mode jumper is located behind the ID switch cover
in the lower left-hand corner of each I/O chassis. The position
of the fault mode jumper determines the module's response to
system level faults. The fault mode jumper’s position will
cause all output modules in the I/O chassis to either shutdown
(set all outputs to zero) or to hold (hold the last state) after a
system level failure occurs. An example of a system level
failure is the failure of two processor modules.
Important!