Rockwell Automation T3464 ICS Regent AC Guarded Digital Output Module - Manual (Page 4)

AC Guarded Digital Output Module (T3464)
4
Industrial Control Services
Table 1. Output States After Switch Failure.
Case
Commanded
Output State
Single
Failure
Actual
Output
to Load Remarks
1 On TRIAC
short
On Continued correct control.
Automatic testing of crowbar
circuit ensures that output will be
able to switch off. If output is
subsequently commanded off,
crowbar switch is energized to
blow fuse and turn off output
(fuse blows 200 msec after
output is commanded off).
2 On TRIAC
open
Off Fail-safe output. Automatic
testing detects failed TRIAC.
3 On Crowbar
fault
On Continued correct control.
Automatic testing detects failed
crowbar circuit. If output is
subsequently commanded off,
TRIAC will turn off.
4 Off TRIAC
short
200
msec
bump
A one-time, 200 msec maximum
on-state bump occurs when the
TRIAC shorts. Automatic testing
detects shorted TRIAC and
crowbar switch is activated to
blow fuse. This one-time bump
may not be suitable for certain
energize-to-trip applications.
5 Off TRIAC
open
Off Fail-safe output. Automatic
testing detects failed TRIAC. If
output is subsequently
commanded on, output will
remain off.
6 Off Crowbar
fault
Off Continued correct control.
Automatic testing detects failed
crowbar circuit. If output is
subsequently commanded on,
TRIAC will turn on.
Testing and Diagnostics
The voter and I/O bus interface logic of the Guarded output
modules 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