Siemens Simatic S7-400

Connection and circuit diagram for SM 421; DI 16 x 24 V DC
INTF
EXTF
1L+
0
1
2
3
1Vs
4
5
6
7
1M
1M
2L+
2L+
0
1
2
3
2Vs
4
5
6
7
2M
2M
1L+
2M
2L+
1M
M
L+
1L+
1L+
2L+
1M
2M
2M
1M
24 V
24 V
24 V
2L+
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Front connector monitoring
Monitoring of external auxiliary voltage 1L+
Monitoring of internal voltage
Short-circuit
protection
Monitoring of encoder supply 1Vs
Monitoring of external auxiliary voltage 2L+
Monitoring of internal voltage
Short-circuit
protection
Monitoring of encoder supply 2Vs
Backplane bus connection
Figure 4-3 Connection and circuit diagram for SM 421; DI 16 x 24 V DC
Digital modules
4.8 Digital input module SM 421; DI 16 x DC 24 V (6ES7421-7BH01-0AB0)
S7-400 Automation System Module Data
Reference Manual, Ausgabe 11/2016, A5E00850736-08 101