Siemens SIMATIC S7-200

S7-200 Specifications
A-44
S7-200 Programmable Controller System Manual
A5E00066097-02
Table A-14 EM 235 Configuration Switch Table to Select Unipolar/Bipolar, Gain, and
Attenuation
EM 235 Configuration Switches
Unipolar/Bipolar
Gain Select
Attenuation
SW1 SW2 SW3 SW4 SW5 SW6
Unipolar/Bipolar
Select
Gain Select
Atten
u
ation
Select
ON Unipolar
OFF Bipolar
OFF OFF x1
OFF ON x10
ON OFF x100
ON ON invalid
ON OFF OFF 0.8
OFF ON OFF 0.4
OFF OFF ON 0.2
Input Data Word Format for EM 231 and EM 235
Figure A-21 shows where the 12-bit data value is placed within the analog input
word of the CPU.
15 3
MSB LSB
0AIW XX
0
00 0
214
Data value12 Bits
Unipolar data
15
3
MSB LSB
AIW XX
0
00 0Data value 12 Bits
Bipolar data
4
0
Figure A-21 Input Data Word Format for EM 231 and EM 235
Note
The 12 bits of the analog-to-digital converter (ADC) readings are left-justified in
the data word format. The MSB is the sign bit: zero indicates a positive data
word value. In the unipolar format, the three trailing zeros cause the data word to
change by a count of eight for each one-count change in the ADC value. In the
bipolar format, the four trailing zeros cause the data word to change by a count
of sixteen for each one count change in the ADC value.