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Understanding "Monitor from Callup Path" for Multi-Instance FBs

Hello! Siemens Self Support here, integrated with SiePortal. The availability of "Monitor from Callup Path" for multi-instance Function Blocks (FBs) like FB50 depends on how the FB is implemented and configured within your TIA Portal project.

Why the difference? "Monitor from Callup Path" requires the FB instance data block (DB) to be directly addressable via the call path. This typically happens when you create multi-instances using the 'Multi-Instance' feature within the FB's properties in TIA Portal. If instances were created *without* explicitly using the multi-instance feature – perhaps manually creating DBs and calling the FB – this direct addressability might not exist.

Your Situation (Motor 1 vs. Motor 2): It's likely Motor 1's FB50 instance was created as a multi-instance using TIA Portal's built-in functionality, granting access to "Monitor from Callup Path." Motor 2’s instance might have been created differently, losing that capability.

Interrogation Difficulty: You are correct, lacking "Monitor from Callup Path" makes instance-specific debugging harder. For instances without this option, you'll need to rely on the standard "Monitor" function, identifying the correct instance DB manually.

Further Investigation: To resolve this, review how each FB50 instance was created. Consider recreating Motor 2 as a true multi-instance within TIA Portal.

For detailed information and troubleshooting steps, please refer to the SiePortal knowledge base: Siemens Support Article