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SIMATIC S7 Ex Analog Modules
3.1 Analog Value Representation
Analog values
3-2
The analog values for all measuring ranges and output ranges which you can
use in conjunction with the S7-300 Ex analog modules are explained in this
section.
3.1.1 Analog Value Representation of Analog Input and Output Values
Conversion of
analog values
Analog value
representation
Table 3-1 Analog value representation
The CPU processes the analog values only in binary form.
Analog input modules convert the analog process signal into digital form.
Analog output modules convert the digital output value into an analog signal.
The digitized analog value is the same for both input and output values with
the same rated range.
The analog values are represented as two’s complement.
Table 3-1 shows the analog value representation of analog modules:
Resolution Analog value
Bit number 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Bit significance Sign 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20 Sign
The sign of the analog value is always in bit number 15:
”0”
”1”
I/O Modules with Intrinsically-Safe Signals
C79000-G7076-C152-04