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Entry type: FAQ Entry ID: 109480387, Entry date: 01/31/2017

How do you implement module and channel diagnostics in the user program of the SIMATIC S7-1200/S7-1500?

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This entry provides a function block for diagnosing channel errors in the central configuration or in an IO module connected via PROFINET IO. This block uses the "RALRM" instruction.

You implement module and channel diagnostics of IO modules that support diagnostics (like the function classes ST and HF of the ET 200SP) by calling the "RALRM" instruction in the diagnostic interrupt OB 82.
Module and channel diagnostics via the SIMATIC S7-1200/S7-1500 is illustrated taking the example of the central IO and via PROFINET IO:

Fig. 1

Using the FB "1x00Diag82" and depending on the controller family used (S7-1200 or S7-1500) you can decode and process per module or channel the diagnostics data of the "RALRM" instruction for the central or distributed configuration via PN IO.

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