Siemens CP 243-2 - Manual (Page 34)

Interface to the User Program in the S7-200 CPU
2-8
SIMATIC NET CP 243-2 AS-i Master
C79000-G8976-C142/02
2.3.1 Identification Register in the Digital Module
Meaning
The identification register signals the I/O module identifier to indicate the existence
of an 8DI/8DO digital module with the value specified below.
The address at which the program can access the identification register depends
on the slot in which the CP 243-2 is inserted.
For further information about the special bit memory and its structure for I/O
modules, refer to /4/.
Range of Values
The identification register can be read via the special bit memory of the S7-200
CPU. It provides the fixed value 05H.
Example
Assuming that the CP 243-2 is inserted directly beside the S7-200 CPU.
The content of the identification register can be read from SMB8.