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Assigning the safety network number (snn), Changing the safety network number (snn) – Rockwell Automation 1768-L45S Compact GuardLogix Controllers User Manual

Page 41

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Rockwell Automation Publication 1768-UM002C-EN-P - April 2012

41

Communicate over Networks

Chapter 4

Assigning the Safety Network Number (SNN)

You can allow RSLogix 5000 software to automatically assign an SNN, or you
can assign the SNN manually.

Automatic Assignment

When a new controller or module is created, a time-based SNN is automatically
assigned via the configuration software. Subsequent new safety-module additions
to the same CIP Safety network are assigned the same SNN defined within the
lowest address on that CIP Safety network.

Manual Assignment

The manual option is intended for routable CIP Safety systems where the
number of network subnets and interconnecting networks is small, and where
users might like to manage and assign the SNN in a logical manner pertaining to
their specific application.

See

Changing the Safety Network Number (SNN) on page 41

.

Automatic Versus Manual

For typical users, the automatic assignment of an SNN is sufficient. However,
manual manipulation of the SNN is required if the following is true:

Safety consumed tags are used.

The project consumes safety input data from a module whose
configuration is owned by some other device.

A safety project is copied to another hardware installation within the same
routable CIP Safety system.

Changing the Safety Network Number (SNN)

Before changing the SNN you must do the following:

Unlock the project, if it is safety-locked.
See

Safety-lock the Controller on page 88

.

Delete the safety task signature, if one exists.
See

Delete the Safety Task Signature on page 91

.

IMPORTANT

If you assign an SNN manually, make sure that system expansion does not
result in duplication of SNN and node address combinations.

This manual is related to the following products: