7.1.1.3.6 Application Example Of Calibration; Table 62: "Calibration" Menu Item - WAGO 750-451 Manual

84 Commissioning

Table 62: "Calibration" Menu Item

Option
Calibration settings
Manufacturer
calibration
User calibration
A/D raw value
Resistance value
[Ohm]
User calibration allows you to calibrate the I/O module individually. The following
calculation formulas apply when calculating both required factors:
• Calibration gain: m = (y2 − y1) / (x2 − x1)
• Calibration offset: b = y1 − m × x1
The variables are assigned as follows:
• m= Calibration gain
• b= Calibration offset
• x1= Actual value 1 (A/D raw value)
• x2= Actual value 2 (A/D raw value)
• y1= Setpoint 1
• y2= Setpoint 2

7.1.1.3.6 Application Example of Calibration

For the calibration, a 2-point measurement with reference resistances is carried
out.
Example:
Measurement 1: y1= 100 Ohm
Measurement 2: y2= 4000 Ohm
Both values of the reference resistances are first converted into corresponding
A/D raw values. The following calculation formula is used:
A/D raw value = (Measure resistance × ((2^24) − 1)) / 5050
Manual
Version 1.2.0
Description
Manufacturer calibration is enabled. Manufacturer-side calibration

is applied. The gain and offset values cannot be entered
individually.
Manufacturer calibration is disabled.

Gain The gain value changes the slope factor of the A/D raw
value.
Offset The offset value moves the zero point of the A/D raw
value (offset on the y axis).
User calibration is enabled. By enabling user scaling, the gain

and offset values can be specified individually.
User calibration is disabled.

Analog/digital converter raw value. This is a 24-bit value.
This is the output value after calculating the gain and offset values and
conversion from A/D raw value. The output is in Ohm.
WAGO-I/O-SYSTEM 750
750-451 8 AI RTD