Rockwell Automation T7485 ICS Regent+Plus Isolated Guarded Output Modules - Manual (Page 4)

Isolated Guarded Digital Output Module (T7485)
4
Industrial Control Services
Testing and Diagnostics
Automatic testing is performed on the isolated Guarded
output modules and its internal output circuits. The output
circuits are completely tested independent of any field load or
power connections. The module does not perform line
monitoring of the wiring connections to field loads.
Module Testing
Each voter and FPGA logic section of the isolated Guarded
output module is automatically tested by the processor
modules. Discrepant data are sent through one of three legs
of the I/O Safetybus to determine whether the module’s voters
are able to outvote the incorrect data. A failure to return the
correct majority-voted result to the processors produces an I/O
module error indication at the processor modules and a
module fault indication at the I/O module.
Each type of module has a unique identification code that is
read by the controller. This code lets the controller know
which type of module is installed in each I/O chassis slot and
how to address that module and its points specifically. If a
module is removed, or is replaced with a module of a different
type, the processor modules will indicate an I/O module error.
Loopback logic tests periodically write data to the module and
then read it back to determine whether the module’s I/O bus
interface logic is functioning correctly.
Output Circuit Testing
The output circuits of the isolated Guarded output module are
automatically tested to detect failures in the redundant
output switch circuits on-board the module. The output fuses
are also checked for blown fuse conditions.
Output Switch Testing
To detect a failure in the redundant output switch circuits,
each output switch is checked for turn-on and turn-off
capability. Periodically, each output switch circuit on the
module is tested for its ability to change its current state.
During testing, the output state is changed; outputs that are
on are turned off and outputs that are off are turned on.
Output switch testing is no-coincident and does not produce a
turn-on pulse to the load. Two output test pulses are