Siemens SIMATIC S7-400 Reference Manual page 102

Digital modules
4.8 Digital input module SM 421; DI 16 x DC 24 V (6ES7421-7BH01-0AB0)
Connection diagram for redundant sensor supply
The image below shows how sensors can be supplied with a redundant voltage source over
Vs (e.g. through another module).
Figure 4-4
Technical specifications for SM 421; DI 16 x 24 V DC
Dimensions W x H x D (mm)
Weight
Number of inputs
Cable length
● Unshielded, input delay
● Shielded, input delay
Rated supply voltage of electronics and sensor L+
● Reverse polarity protection
Number of inputs that can be enabled simultaneously
Electrical isolation
● Between channels and backplane bus
● Between channels and electronics power supply
● Between channels
Permissible potential difference
● Between different circuits
Insulation tested at
● channels against rear panel and load voltage L+
● Between channel groups
Current consumption
● from backplane bus (5 V)
102
Short-circuit-
proof driver
Digital input
module
Connection diagram for redundant sensor supply for SM 421; DI 16 x 24 V DC
0.1 ms
0.5 ms
3 ms
0.1 ms
0.5 ms
3 ms
in groups of
L+
1 L+
Vs
2 L+
M
±
to the sensors
Dimensions and weight
Module-specific data
Voltage, current and potential
Reference Manual, Ausgabe 11/2016, A5E00850736-08
25 x 290 x 210
ca. 600 g
16
20 m maximum
50 m maximum
600 m maximum
30 m maximum
70 m maximum
1000 m maximum
24 V DC
Yes
16
Yes
No
Yes
8
60 V DC/30 V AC (SELV)
500 V DC
500 V DC
130 mA maximum
S7-400 Automation System Module Data