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Manual VIPA System SLIO
Chapter 4 Analog Input
HB300E - SM - Rev. 09/38 4-3
Analog value
Analog values are exclusively processed by the CPU in a binary format. For
this the analog module transforms every process signal into a digital value
and transfers this as word.
Resolution Analog value
High byte (byte 0) Low byte (byte 1)
Bit number 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Value SG 2
14
2
13
2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
12bit + sign SG Measuring value 0 0 0
15bit + sign SG Measuring value
With a resolution of 12bit plus sign bit, the not used low value positions
(3bits) are filled with "0".
The algebraic sign bit is represented by bit 15. Here it is essential:
Bit 15 = "0"
→
positive value
Bit 15 = "1"
→
negative value
As soon as a measured value exceeds the overdrive region respectively
falls below the underdrive region, the following value is issued:
Measuring value > end of overdrive region:
32767 (7FFFh)
Measuring value < end of underdrive region: -32768 (8000h)
At a parameterization error the value 32767 (7FFFh) is issued.
Representation of
analog values
Resolution
Sign bit (SG)
Behavior at error