Rockwell Automation 1732DS-IB8 User Manual page 49

For example, assume there are two identical GuardLogix
control systems - system A and system B - that are connected
to a common Ethernet network. Each GuardLogix control
system has three DeviceNet networks with assorted standard
and safety I/O modules. In a system like this, modules can
have the same node number, but no two modules have the
same SNN and node number combination.
If 1756-DNB modules were in the same chassis, and the
DeviceNet cables were inadvertantly disconnected, if
reattached incorrectly, the connections to the safety modules
are broken, because the 1756-DNB module is now connected
to devices with a different SNN.
Note that we suggest that all safety modules on a network have
the same SNN. This makes documentation easier. During
configuration, RSLogix 5000 software defaults a safety device's
SNN to match the SNN of the lowest safety node on the
network.
D. Click Change to see the Module Definition dialog.
E. From the Module Definition dialog, select values to configure
what data and status tags to generate implicitly for the safety
module, noting that you can configure Input Data, Input Status,
and Output Data.
Configure Modules in RSLogix 5000 Software
Publication 1791DS-UM001H-EN-P - April 2009
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