Rockwell Automation Publication 1756-UM013B-EN-P - October 2019
95
Configure and Replace Safety Modules
Chapter 5
Replace a Module in a Logix 5000 System
Consider the following conditions before you replace a safety module in a
Logix 5000™ system:
• If you rely on a portion of the CIP Safety system to maintain SIL 3
behavior during module replacement and functional testing, you must use
the Configure Only When No Safety Signature Exists feature.
• If there is only one safety controller on the network, or if you do not rely
on the entire routable CIP Safety control system to maintain
SIL 3/PL (d or e) during the replacement and functional testing of a
module, you can use the Configure Always feature.
Replacement with `Configure Only When No Safety Signature Exists’ Enabled
When a module is replaced, the configuration is downloaded from the safety
controller if the DeviceID of the new module matches the original. The
DeviceID is updated whenever the SNN is set.
If the project is configured with Configure Only When No Safety Signature
Exists enabled, follow the appropriate instructions in to replace a 1756
ControlLogix digital safety I/O module.
After you complete the steps in a scenario correctly, the DeviceID matches the
original. This match enables the safety controller to download the proper module
configuration, and re-establish the safety connection
Table 26 - Replacing a Module
GuardLogix® Safety
Signature Exists
Replacement
Module Condition
Action Required
No
No SNN (Out-of-box)
None. The device is ready for use.
Yes or No
Same SNN as original
safety task
configuration
None. The device is ready for use.
Yes
No SNN (Out-of-box)
See Scenario 1 - Replacement Device is Out-of-box and
Safety Signature Exists on page 96
.
Yes
Different SNN from
original safety task
configuration
No
Summary of Contents for 1756 Series
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