Siemens ET 200S Manual page 362

Analog Electronic Modules
12.1.1 Analog Value Representation for Measuring Ranges with
SIMATIC S7
Analog Value Representation
The digitized analog value for input and output values is the same in the same
rated range. Analog values are represented in twos complement.
The following table shows the analog value representation of the analog electronic
modules.
Table 12-2 Analog Value Representation (SIMATIC S7 Format)
Resolution
Bit number
Significance of the bits
Sign
The sign (S, +/–) of the analog value is always in bit number 15:
S "0" ³ )
S "1" ³ *
Measured-Value Resolution
In the table below, you will find the representation of the binary analog values and
the associated decimal and hexadecimal representation of the units of the analog
values.
Table 12-3 shows the resolutions 11-, 12-, 13-, and 15 bits + sign (S). Each analog
value is entered in the accumulator with left justification. The bits marked "x" are
set to "0".
12-6
15 14 13 12 11
14 13 12 11
S 2 2 2 2
Analog Value
10 9 8 7 6 5
10 9 8 7 6 5
2 2 2 2 2 2
Distributed I/O System ET 200S
4 3 2 1 0
4 3 2 1 0
2 2 2 2 2
EWA 4NEB 780 6024-02 07