44 Rockwell Automation Publication 1734-UM013N-EN-P - September 2017
Chapter 2 Safety Inputs, Safety Outputs and Safety Data
Muting Lamp Operation
(1734-IB8S)
Beginning with Firmware Revision 1.002, the operation of the muting status bits
for the test outputs T1 and T3 has changed. 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. Figure 21 explains how muting lamp operation, status,
and fault detection are monitored.
Figure 21 - Muting Lamp Timing Diagram
Table 4 shows the expected behavior of the muting status for test outputs T1 and
T3. Keep these points in mind as well:
• When power is applied to the 1734-IB8S module, and T1 or T3 remains
commanded off, the muting status defaults to on.
The lamp test interval is 3 seconds. Two consecutive failed lamp tests are
required to declare a burned-out lamp condition. The lamp test does not
always run immediately after the test output is energized. It starts at the next
3-second interval. To allow time for two consecutive test intervals, program a
minimum Test Output On Time of 6 seconds.
1 Burnt-out lamp detected
2 Good lamp detected
3 Intermittent lamp testing stopped
4 Intermittent lamp testing started
Connected
Connected
Disconnected
Disconnected
Bulb Disconnected / Burnt-out
Muting Lamp
Lamp Test
Muting Status
T3 Output*
Off
Off
On
On
Bulb Connected / Good
Good
Burnt-out
Inactive
Active
Test
Time
Test Interval
* Note: Output controlled by User program, not by Muting Status bit.
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