Siemens S5-100U - Page 58

Installation Guidelines S5-100U
The common chassis grounding connection makes it possible for you to use reasonably priced non-
floating I/Os.
These modules function according to the following principles.
• Input modules
- The ground line, line M (control circuit chassis) is the reference potential. A voltage drop V
1
on
line affects the input signal level
V
I
.
• Output modules
- Terminal 2 (M)
of the terminal block is the reference potential. A voltage drop V
2
on the
line raises the chassis potential of the output driver and thus reduces the resulting control
voltage V
CV
.
Figure 3-22 shows a simplified connection of the S5-100U with a non-floating external I/O.
Figure 3-22. Simplified Representation of a Non-Floating I/O Connection
+9 V
Data
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24 V DC supply
3-26 EWA 4NEB 812 6120-02