Beckhoff analog input

[hapetter]

Hi.

I try to understand how to read an analog input (4-20mA). Using TwinCAT.

I found this example on how to scale the input into engineering units:

Eksempel
0-60 bar fra 4-20 mA resolution 0.1 bar:

FACTOR = 10
Data @ 4 mA = 6240
Data @ 20 mA = 31208
DataOffset = 6240
DataSpan = 31208 - 6240 = 24968
EUOffset = 0 x 10 = 0
EUSpan = (60 - 0) x 10 = 600

DATA = 18975

EU = ((600 x (18975 - 6240)) / 24968) + 0 = 306

Process value = 306 / 10 = 30.6 bar

1. Is this a good approach?
2. How to set up VAR types?
3. All variables of types word?
4. Should FACTOR allways be 10?
5. Is DATA buffer (12bit) a value between 0-32000?

Thanks!

Best Regards
Hans Pettersson