Rockwell Automation 1791DS-IBxxxx Guard I/O DeviceNet Safety Modules User Manual
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Rockwell Automation Publication 1791DS-UM001J-EN-P - May 2013
Chapter 6
Configure Modules in RSNetWorx for DeviceNet Software
software defaults a safety device’s SNN to match the SNN of the lowest safety
node on the network.
The safety connection between a controller and I/O module is based on many
items, one of which is the SNN of both devices. They do not have to match for a
safety connection to be established, but the connection will be broken if the SNN
of either device changes.
The safety network defaults to match the SNN of the lowest node on the
network. If your safety controller is the lowest node on the network, then all of
the safety I/O modules on the network will have the same SNN as the controller.
As this is the recommended method of configuring the SNN, you may not need
to do anything more with the SNN.
For a detailed explanation of the SNN, see the GuardLogix Controller Systems
Safety Reference Manuals listed in the Additional Resources on