Siemens S7-400 Manuel D’Utilisation

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Digital Modules
4-25
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Terminal Assignment Diagram for Redundant Supply of Sensors
The figure below shows how sensors can additionally be supplied by means of Vs
with a redundant voltage source – for example, via another module).
 Vs
M
L+
1 L+
2 L+
to the sensors
±
Digital input
module
Short-circuit-
proof driver
Figure 4-5
Terminal Assignment Diagram for the Redundant Supply of Sensors of the 
SM 421; DI 16 
 
 24 VDC
Technical Specifications of the SM 421; DI 16 
 
 24 VDC
Dimensions and Weight
Dimensions W 
 
 H 
 
 D
(in millimeters)
25 
 
 290 
 
 210
Weight
Approx. 600 g
Data for Specific Module
Number of inputs
16
Length of cable
Unshielded
input delay
0.1 ms
0.5 ms
3 ms
Max. 20 m
Max. 50 m
Max. 600 m
Shielded
input delay
0.1 ms
0.5 ms
3 ms
Max. 30 m
Max. 70 m
Max. 1000 m
Voltages, Currents, Potentials
Rated supply voltage of the
electronics and sensor L+
24 VDC
Reverse polarity protection
Yes
Number of inputs that can be
triggered simultaneously
16
Isolation
Between channels and
backplane bus
Yes
Between channels and
power supply of the
electronics
No
Between the channels
Yes
In groups of
2
Permitted potential difference
Between the different
circuits
75 VDC, 60 VAC
Insulation tested with
Channels against
backplane bus and load
voltage L+
500 VDC
Channel groups between
themselves
500 VDC
Current consumption
From the backplane bus
From the power supply L+
Max. 130 mA
Max. 120 mA
Power dissipation of the
module
Typ. 5 W