Signaling Errors and Diagnostics in the User Program

4.1Signaling

Error Signaling

If the CP 243-2 recognizes errors on the AS-Interface (AS-i slave failure, AS-i Power Failure) during operation, it signals these errors by resetting the input data of the affected slave and by setting the corresponding bit in the error register in the SM area (Special Memory).

The SM byte addresses depend on the slot of the CP 243-2.

Caution

!Note that the operating system of the S7-200 CPU does not always update the error register in the SM area before a program cycle. For this reason, it is possible that the input data of a binary AS-i slave are set to '0' although no error is signaled in the error register.

If you require a consistent view of the input data, error bits and the delta list for programming your system, you can achieve this using the ªRead Data and Delta Listº command (see Section 5.2.32).

4-2

SIMATIC NET CP 243-2 AS-i Master

C79000-G8976-C142/02

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Siemens CP 243-2 installation instructions Error Signaling