Siemens S7-300 Installation And Operating Manual page 112

Digital modules
8.4 SM 326; DI 8 x NAMUR
Minimum thread length with SM 326; DI 8 x NAMUR for Hazardous Area
Always maintain a minimum thread length of 50 mm between connections with PELV and
intrinsically safe terminals of SM 326; DI 8 x NAMUR. This can be achieved by installing a
cable guide in the front connector.
The minimum thread length between conductive parts may be less than 50 mm in a system
which contains EX and standard modules.
To comply with thread length requirements at the modules:
● Always install the SM 326; DI 8 x NAMUR in the S7-300/ET 200M rack at the last position
● Insert the DM 370 dummy module between the relevant EX and the standard modules if
● You can also install an intrinsically safe partition when using modules of the active
Additional information on the Hazardous Area
For further information on using the DM 370 and the Ex partition, and on separating the
intrinsically safe and non-intrinsically safe wiring, refer to the
M7-300, ET 200M Programmable Controllers, I/O Modules with Intrinsically-Safe Signals
Reference Manual.
112
WARNING
on the extreme right of the mounting rail; the width of SM 326; DI 8 x NAMUR
automatically corrects the thread length to the next module on its left side.
this cannot be done.
backplane bus.
WARNING
Always separate the intrinsically safe from the non-intrinsically safe wiring. Route these
through separate cable ducts.
Automation Systems S7-300,
Installation and Operating Manual, 01/2010, A5E00085586-10
Fail-safe signal modules