Rockwell Automation 1753-DNSI DeviceNet Safety Scanner for GuardPLC Controllers - Manual (Page 37)

1 Publication 1753-UM002A-EN-P - July 2005
Chapter
4
Manage the Safety Network Number
Safety Network Numbers assigned to each safety network or network
sub-net must be unique. You must ensure that a unique Safety
Network Number (SNN) is assigned to each DeviceNet network that
contains safety nodes.
Each DeviceNet Safety device must be configured with an 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 to a node
with the same node address on a different DeviceNet subnet.
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.
Time-based SNN (Recommended)
In the time-based format, the SNN represents the date and time at
which the number was generated, according to the personal computer
running RSNetWorx for DeviceNet.