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Rockwell Automation Publication 1756-UM013B-EN-P - October 2019
Appendix C
Application and Wiring Examples for Safety Modules
When the module is wired as shown, it is suitable for applications that are rated
up to, and including,
Category 4
and
PLe
as defined in ISO 13849-1.
To achieve that suitability rating, you may have to perform diagnostic testing and
monitoring of the safety function. One diagnostic test method is to configure the
safety output channel for Safety Pulse Test to test the circuit for short circuits to
24V DC.
• The application is configured so that a No Load fault can only be detected
if the wires from
both
the P- terminal and the M-terminal
are disconnected.
For Cat.4 applications, if your application remains in safe state, that is, the output
is off, for a prolonged duration, we recommend that you take one of these actions:
• Apply output monitoring at the actuator. The monitoring can be direct or
indirect.
• Limit the safe state to no more than 24 hours.
• Conduct functional test if safe state dwell time increases.
DC(+)
DC(-)
DC(+)
DC(-)
OUT0-P
OUT1-P
OUT4-P
OUT3-P
OUT2-P
OUT5-P
OUT6-P
OUT7-P
OUT0-M
OUT1-M
OUT2-M
OUT3-M
OUT4-M
OUT5-M
OUT6-M
OUT7-M
+ -
24V DC
SELV/PELV-listed power
supply
Channel Connections
This wiring example shows connections to the P-M pair for Safety
Output 0. You are not limited to using channel 0 in this mode. You
can use all channel pairs as determined by your application.
Connection Pairs
The terminals for each channel function as a Bipolar connection
pair when you use a 1756-OBV8S module in Bipolar switching
mode. For example, the Safety Output 0 P (Sourcing) terminal and
Safety Output 0 M (Sinking) terminal are a Bipolar connection pair.
That is, they are a P-M pair.
When the module is in Bipolar switching mode, you must connect
the device to both terminals.
We
strongly recommend
that, if you have a direct connection
between the safety output module and an input module and those
modules are powered by separate power supplies, you connect the
DC- terminals together. This practice helps to eliminate grounding
float from disrupting diagnostics.
K
K
M