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Rockwell Automation Publication 1756-UM013B-EN-P - October 2019
Chapter 4
1756-OBV8S Output Module Features
Safety Output with Test
Pulse
When the safety output is on, the safety output can be configured to pulse test
the safety output channel. By using this function, you can continuously test the
ability of the safety output to remove power from the output terminals of the
module.
If an error is detected, the safety output data and individual safety output status
turn off.
Figure 13 - 1756-OBV8S Test Pulse in a Cycle
On the 1756-OBV8S module, the pulse width (X) is less than 750 µs, and the
pulse period (Y) is less than 96 ms.
TIP
To help prevent the test pulse from causing the connected device to
malfunction, pay careful attention to the input response time of the
output device.
An open wire test and main switch pulse test can also generate a pulse on a
safety output even in safety mode.
Two successive safety output pulses are required to determine if a short
circuit fault exists. As a result, the effective pulse period is 192 ms, max.
OUT
X
Y
On
Off
OUT
X
Y
Off
On
Sourcing Output
Sinking Output
Summary of Contents for 1756 Series
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