Siemens SIMATIC S7-400 Hardware And Installation Manual page 211

Connecting Mass Storage Modules (MSM)
Pin assignments of the parallel interface of the MSM 478 mass storage module
can be found in the chapter on M7-400 expansion of the Reference Manual.
Connecting the Short AT Card
The interface pin assignments of short AT cards which you intend to use can be
found in the corresponding documentation.
S7-400 and M7-400 Programmable Controllers, Installation Manual
C79000-G7076-C424-01
www.gkbpx.com
Assembling the M7-400
8-29