88
Commissioning
WAGO-I/O-SYSTEM 750
750-451 8 AI RTD
Manual
Version 1.1.0
Example:
y1 = (100 Ohm × ((2^24)
−
1)) / 5050 = 332222
y2 = (4000 Ohm × ((2^24)
−
1)) / 5050 = 13288883
For each of the two calibration points, you should record as many A/D raw values
as possible (at least 10).
Example:
A/D raw values recorded at 100 Ohm (10 measured values total):
A/D raw value 1:
333887
A/D raw value 2:
333895
A/D raw value 3:
333893
A/D raw value 4:
333895
A/D raw value 5:
333892
A/D raw value 6:
333882
A/D raw value 7:
333881
A/D raw value 8:
333900
A/D raw value 9:
333900
A/D raw value 10: 333895
A/D raw values recorded at 4000 Ohm (10 measured values total):
A/D raw value 1:
13287113
A/D raw value 2:
13287092
A/D raw value 3:
13287087
A/D raw value 4:
13287107
A/D raw value 5:
13287073
A/D raw value 6:
13287107
A/D raw value 7:
13287094
A/D raw value 8:
13287132
A/D raw value 9:
13287098
A/D raw value 10: 13287131
In the next step, determine the average for each of the two reference resistances
from the recorded A/D raw values. By calculating the average, you get the x1 and
x2 values.
Example:
At 100 Ohm, x1 is = 333892
At 4000 Ohm, x2 is = 13287103
You can now use all calculated values in the calculation formulas and get the
calibration gain and calibration offset.
The calibration gain is the slope factor and the calibration offset gives you the
factor for displacement on the y axis.
