Siemens Simatic M7-400 Reference Manual page 491

Permissible Dimensions of AT Modules
The following illustration shows you the maximum and minimum dimensions in
millimeters that AT modules must meet for the ATM 478 AT adapter module. If
these dimensions are not conformed to, proper installation in the ATM 478 AT
adapter module is no longer possible.
0.8
4.3
0
12.2
Figure 12-9 Dimension Specifications for AT Modules to be Installed in an ATM 478
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
3 min.
108.76
164 max.
18.4
14
10.9
2.85
0
5.9
8
Components max. insertion height 14 mm
2.84
M7-400 Expansions
12-21