Siemens SIMATIC S7-400 Reference Manual page 61

Note
You assign addresses for the intermediate memory from the DP address area of
the CPU 41x.
You must not reassign the addresses you have already assigned to the
intermediate memory to the I/O modules on the CPU 41x.
• The lowest address in each address area is the start address of that address
area.
• The length, unit and consistency of address areas for the DP master and DP
slave that belong together must be the same.
S5 DP Master
If you use an IM 308 C as a DP master and the CPU 41x as a DP slave, the
following applies to the exchange of consistent data:
You must program FB 192 in the IM 308-C so that consistent data can be
transferred between the DP master and DP slave. The data of the CPU 41x are
only output or displayed contiguously in a block with FB 192.
S5-95 as DP Master
If you use an AG S5-95 as a DP master, you must also set its bus parameters for
the CPU 41x as DP slave.
Automation System S7-400 CPU Specifications
A5E00165965-01
Structure of a CPU 41x
1-49