User Manual

Rockwell Automation Publication 1752-UM001E-EN-P - June 2014 61
Chapter 5
Manage the Safety Network Number
Introduction
Each DeviceNet Safety device must be configured with a safety network number
(SNN). The combination of SNN and DeviceNet node address provides a
unique identifier for every safety node in a complex industrial network. This
unique identifier prevents data intended for a specific target node address on one
DeviceNet subnet from being mis-routed and accepted by a node with the same
node address on a different DeviceNet subnet.
Safety network numbers assigned to each safety network or network sub-net
must be unique. You must be sure that a unique safety network number (SNN) is
assigned to each DeviceNet network that contains safety nodes.
Safety Network Number
(SNN) Formats
The safety network number (SNN) can be either software-assigned (time-based)
or user-assigned (manual). These two formats of the SNN are described in the
following sections.
Topic Page
Safety Network Number (SNN) Formats 61
Assignment of the Safety Network Number (SNN) 62
Set the Safety Network Number (SNN) in All Safety Nodes 63
Safety Network Number (SNN) Mismatch 65
Safety Network Number (SNN) and Node Address Changes 65