User manual

Publication 1756-RM093F-EN-P - January 2010 37
CIP Safety and the Safety Network Number Chapter 4
Each CIP Safety device must be configured with an SNN. Any device
that originates a safety connection to another safety device must be
configured with the SNN of the target device. If the CIP Safety system
is in the start-up process prior to the functional safety testing of the
system, the originating device may be used to set the unique node
reference into the device.
The SNN used by the system is a 6-byte hexadecimal number. The
SNN can be set and viewed in one of two formats: time-based or
manual. When the time-based format is selected, the SNN represents a
localized date and time. When the manual format is selected, the SNN
represents a network type and a decimal value from 1…9999.
SNN Formats
The assignment of a time-based SNN is automatic when creating a
new GuardLogix safety controller project and adding new Safety I/O
modules.
Manual manipulation of an SNN is required in the following situations:
• If safety consumed tags are used.
• If the project will consume safety input data from a module
whose configuration is owned by some other safety device.
• If a safety project is copied to a different hardware installation
within the same routable CIP Safety system.
IMPORTANT
If you assign an SNN manually, take care to ensure that system
expansion does not result in duplication of SNN and node
address combinations.