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Rockwell Automation Publication 1734-UM013C-EN-P - August 2010
Chapter 2
Safety Functions
Muting Lamp Operation
(test outputs T1 and T3)
Beginning with firmware revision 1.2, we made changes to the operation of the
muting status bits for the test outputs T1 and T3. Test outputs T1 and T3 are
controlled by your PLC processor program to illuminate a muting lamp. Muting
lamp status is monitored with a test that runs periodically during every test
interval to detect a burned-out lamp. The test runs repeatedly when the test
output is commanded on. The figure below explains how muting lamp operation,
status, and fault detection are monitored.
TIP
The lamp test interval is 3 seconds. Two consecutive lamp tests are
necessary to identify a faulty muting lamp to detect a burned-out lamp
condition. The lamp test may not run immediately after the test output
turns on. So that there is time for two consecutive test intervals, we
recommend that you program a minimum test output on time
of 6 seconds.