Replace a Safety Module in a Logix 5000 System

Consider the following conditions before you replace a safety I/O 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 you 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 the table to replace a 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.
Replace a Safety I/O Module
Controller Safety Signature Exists
Replacement Module Condition
Action Required
No
No SNN (Out-of-box)
None. The module is ready for use.
Yes or No
Same SNN as original safety task configuration
None. The module is ready for use.
Yes
No SNN (Out-of-box)
Complete the steps in Set the SNN Manually.
Yes
Different SNN from original safety task configuration
No
  2. Follow your company-prescribed procedures to functionally test the replaced I/O device and system and to authorize the system for use.

Replacement with ‘Configured Always’ Enabled

ATTENTION:
Enable the ‘Configure Always’ feature only if the entire CIP Safety Control System is not being relied on to maintain SIL 3 behavior during the replacement and functional testing of a module.
Do not place modules that are in the out-of-box condition on a CIP Safety network when the Configure Always feature is enabled, except while following this replacement procedure.
When the ‘Configure Always’ feature is enabled, the controller automatically checks for and connects to a replacement module that meets all the following requirements:
  • The controller has configuration data for a compatible module at that network address.
  • The module is in out-of-box condition or has an SNN that matches the configuration.
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