Rockwell Automation 1791DS-IBxxxx Guard I/O DeviceNet Safety Modules - Manual (Page 121)

Rockwell Automation Publication 1791DS-UM001J-EN-P - May 2013 121
Considerations When Replacing Guard I/O Modules Chapter 7
Replacing an I/O Module
When Using a GuardLogix
Controller Follow the appropriate steps to replace an I/O module when using a GuardLogix
controller.
I/O Replacement with ‘Configure Only When No Safety Signature
Exists’ Enabled
If a safety signature exists, clicking Set downloads the correct SNN from the
correct GuardLogix project to the replacement module. The only exception
would be when the SNN is already the same as the replacement module, in which
case no action is required.
Once the correct SNN has been downloaded to the Guard I/O module, the
GuardLogix controller automatically configures the module.
IMPORTANT If you use a GuardLogix controller for SIL 3 during module replacement and
functional testing, then you must choose ‘Configure Only When No Safety
Signature Exists’. This option makes sure that if a safety signature exists
(and you must have a safety signature to be SIL 3), that the safety network
number (SNN) of the replacement distributed I/O module must match that
of the GuardLogix controller before a connection between them can be
made.