Siemens Simatic M7-400 Reference Manual page 140

Digital Modules
Terminal Assignment and Block Diagram of the Digital Input Module SM 421;
DI 32 x 24 VDC
Process
L+
M
Figure 4-2 Terminal Assignment and Block Diagram of the SM 421; DI 32
4-18
Module
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2
L+
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4
0
5 1
6 2
3
7
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9 5
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11 7
12
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16 1
17
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3
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34 7
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0
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40
41
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43
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45
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46 7
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48
M
S7-400, M7-400 Programmable Controllers Module Specifications
t
t
t
t
24 VDC
A5E00069467-07