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Siemens Simatic S7-400 User Manual

Page 147

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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

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