SIMATIC System and Standard Functions for S7-300 and S7-400

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AINFO parameters
AINFO is the source area for additional interrupt information. As far as the intelligent slave is concerned, you can fill this area with any values that you wish. However, if you are using a DP master of the S7 family, the additional information sent along with the interrupt must conform to S7 conventions.
If you send a diagnostic interrupt (ATYPE=1), then you are responsible for entering appropriate, relevant values in data record 0, and if necessary, also in data record 1.
The following table shows you a proposed set of S7-compatible entries. In this case, the "module fault" bit (see above) was already set. Up to actually naming the bit, this suggestion corresponds to the default assignment (the one existing after a POWER UP, after a STOP-RUN transition at the intelligent slave or a station return).