WAGO-I/O-SYSTEM 750
Commissioning 65
750-496 8AI 0/4-20mA S.E.
Manual
Version
1.2.2
7.2
Calibrating Measured Values
User calibration serves to compensate for tolerances in electrical components.
Calibrate the I/O module by channel to achieve maximum measurement accuracy
for each channel.
User calibration by channel required!
Calibrate separately for each channel.
The following sensor types are specified:
Table 33: Sensor Types
ID
Sensor type
1
0 … 20 mA
2
4 … 20 mA
3
3.6 … 21 mA (NAMUR NE43)
The variables in the following equations have the following meaning:
Table 34: Variable Legend – Calibrating Measured Values
Variable
Meaning/function
m
Calibration gain (gain factor)
b
Calibration offset (offset)
x1
Actual value 1 (analog input current)
x2
Actual value 2 (analog input current)
y1
Setpoint 1
y2
Setpoint 2
The “Gain” and “Offset” values are required to perform user-defined calibration.
The calibration gain is the gain factor. The calibration offset is the offset on the y
axis. The following general calibration equation applies:
y = (x + b) × m
The general calibration equation yields the following two equations for calculating
the two values sought:
Calibration gain: m = (y2 – y1) / (x2 – x1)
Calibration offset: b = (y1 / m) – x1