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What is the meaning of the signature value on the PLC Screen in Control Expert?

Published date: 25 July 2019

The M580 PLC Screen has the application signature value composed of 4 valuesand customers would like to know the meaning of each value to monitor the application

Product Line
M580 v2.80    

Control Expert v14, Unity Pro v13.1 or older 

The version application signature is composed of 4 values -> CID-MID-AID-LID and you can find bellow the description of each one of the values:
  • CID - Creation ID: Random number generated when an application is created. The number remains a constant.
  • MID - Modification ID: Random number generated on each application modification and rebuild, either partial or global. When an application is created, MID = CID.
  • AID - AutoModification ID: A new random value generated for AID by the PLC after one of the following minor modifications to the application:
    • ​a Control Expert request to modify %KW
    • a P_Unit request that performs a save_param request or replaces init value
​​           When an application is created or built in local mode, AID = 0.
  • LID - Layout ID: Random number generated after a modification of the variable layout. LID does not change as a result of a runtime change either adding or deleting a data block. LID changes only on when the global rebuild of the application.
​           LID addresses the needs of Hot Standby. It permits the transfer of a memory block from the primary PLC to the standby so that application variables (excepted for deleted or new ones) exist at the same location
           LID = CID = MID when the application is created.

You can find below a sample of the signature value.
  • Value when the application was created
  • Value after a build changes
  • Value after Rebuild all 

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