Allen-Bradley 1734-OB8S - Safety Inputs; Using a Test Output with a Safety Input

Rockwell Automation Publication 1734-UM013C-EN-P - August 2010 21
Safety Functions Chapter 2
Safety Inputs
Read this section for information about safety inputs and their associated test
outputs. A safety input can optionally be used with test outputs. Safety inputs are
used to monitor safety input devices.
Using a Test Output with a Safety Input
A test output can be used in combination with a safety input for short circuit,
cross-channel, and open-circuit fault detection. Configure the test output as a
pulse test source and associate it to a specific safety input.
Figure 4 - Example Use of a POINT Guard I/O Input Module
Figure 5 - Test Pulse in a Cycle
For the 1734-IB8S module, the pulse width (X) is typically 525 μs; the pulse
period (Y) is typically 144 ms.
TIP
The test output can also be configured as a power supply to
source 24V DC to an external device, for example, a light
curtain.
I0 I1 I4 I5
I2 I3 I6 I7
COM
Where:
T0 = Test Output 0
T1M = Test Output 1 with Muting
T2 = Test Output 2
T3M = Test Output 3 with Muting
I0…I7 = Safety Inputs
COM COM COM
TO T1M T2 T3M
0
2
4
6
1
3
5
7
0
2
4
6
1
3
5
7
Safety Input
Terminal
External
Contact
X
OUT
Y
On
Off