A4: Digital and analog NCK I/Os for SINUMERIK 840D sl
1.2 Access via PLC
Extended Functions
Function Manual, 03/2013, 6FC5397-1BP40-3BA1
43
1.2.4.3 Representation of the NCK analog input/output values
The digitized analog values are represented at the NC/PLC interface as fixed-point numbers
(16 bits including sign) in the two's complement.
Bit number 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Significanc
e
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
SG: Sign
Minimum value Maximum value
-32768
D
32767
D
8000
H
7FFF
H
Increment
For a resolution of 16 bits and a nominal range of ±10 V, the increment is:
20 V / 2
16
= 20 V / 65536 ≈ 0.305 mV
Resolutions < 16 bits
If the resolution of an analog module is less than 16 bits including sign, then the digitized
analog value is entered in the interface starting from bit 14. The unused least significant bit
positions are filled with "0".
14-bit resolution
For a resolution of 14 bits including sign and a nominal range of ±10 V, the increment is:
20 V / 2
14
= 20 V / 16384 ≈ 1.22 mV
Bit 0 ... 1 are always "0".
12-bit resolution
For a resolution of 12 bits including sign and a nominal range of ±10 V, the increment is:
20 V / 2
12
= 20 V / 4096 ≈ 4.88 mV
Bit 0 ... 3 are always "0".
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