Siemens SIMATIC S7-200 System Manual page 435

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Figure A-20 Output Data Word Format for EM 232 and EM 235
Tip
The 12 bits of the digital-to-analog converter (DAC) readings are left-justified in the output data
word format. The MSB is the sign bit: zero indicates a positive data word value. The four trailing
zeros are truncated before being loaded into the DAC registers. These bits have no effect on the
output signal value.
Output Block Diagram for EM 232 and EM 235
Vref
D/A converter
11
DATA
Digital-to-analog converter
Figure A-21 Output Block Diagram for the EM 232 and EM 235
MSB
15 14
0 Data value
Current output data format
MSB
15
Data value
Voltage output data format
R
+
--
R
+/-- 2V
0
1/4 R
Technical Specifications
4 3
11 Bits 0 0
4 3
12 Bits 0 0
100
--
+
Voltage-to-current converter
+
--
R
Voltage output buffer
M
Appendix A
LSB
0
0 0
LSB
0
0 0
+24 Volt
Iout
0..20 mA
Vout
--10.. +10 Volts
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