Siemens Simatic S7-400 - Manual (Page 208)

Digital Modules
4-86
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Changing Fuses
!
Warning
This can result in injury.
If you change a fuse without removing the front connector of the module, you could
be injured by an electric shock.
Consequently, always remove the front connector before you change the fuse.