Siemens Simatic S7-200 System Manual page 387

Input Block Diagram
Figure A-36 shows the EM231 input block diagram.
A+
R
RA
C
Rloop
C
A-
R
B+
R
RB
C
Rloop
C
B-
R
C+
R
RC
C
Rloop
C
C-
R
Input differential and
common-mode filter
Figure A-36 EM231 Input Block Diagram
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02
+
C
Buffer
-
R
A=0
R
C
R
A=1
R
C
R
A=2
A=3
Input selector Attenuation stage
S7-200 Data Sheets
xGAIN
A/D Converter
11
Analog-to-digital converter
Gain
x1
SW1
SW3
AGND
Gain stage
Vref
0
DATA DATA
A-63