Safety Network Number - Allen-Bradley ControlLogix 5570 Reference Manual

Chapter 4 Replacement Considerations with Safety Applications

Safety Network Number

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The safety network number (SNN) uniquely identifies CIP Safety™ subnets
within a routable safety network. The combination of the SNN + Node
Address uniquely identifies each CIP Safety port on each device in the routable
safety network.
GuardLogix 5570
GuardLogix 5570 controllers have one SNN for the
backplane communications.
Compact GuardLogix 5370
Compact GuardLogix 5370 controllers have one SNN for
the embedded Ethernet ports.
For an explanation of the Safety Network Number, see the GuardLogix 5580
and Compact GuardLogix 5380 Controller Systems Safety Reference Manual,
publication 1756-RM012.
Rockwell Automation Publication 1756-RM100F-EN-P - October 2018
GuardLogix 5580
The GuardLogix 5580 requires two SNNs, one for the
embedded Ethernet port, and one for the backplane
communications
Compact GuardLogix 5380
The Compact GuardLogix 5380 controllers have a SNN
for each embedded Ethernet port, and one for the
backplane communications