Siemens S7-400 Benutzerhandbuch

4-16

S7-400, M7-400 Programmable Controllers Module Specifications

A5E00069467-07

As long as the current flowing into the module remains 

v

 1.5 mA, the module

recognizes this as a “0” signal.

0.5

1.5

2

6

7

0

5

11 13 15

24

30

I 

min

 to IEC 61131; type 2

I 

min

 to IEC 61131; type 1

Typ. switching threshold

(9.5 V)

Resistance characteristic

curve

L+ (V)

– 30 V

I 

E

  (mA)

“0”

“1”

1

0

L+

M

I 

v

 1.5 mA

-->  “0” signal

PLC 

input resistance

2-Wire BERO

BERO

standard

I 

v

 1.5 mA

Figure 4-1

Input Characteristic Curve for Digital Inputs

The input current in the case of the digital input module (6ES7421-1BL01-0AA0)
reaches 1.5 mA only above the +5 V switching threshold but under the switching
threshold of the module (typ. 9.5 V). Therefore only type 1 can be specified with the
IEC 61131 standard.