Example Of Determining Gain And Offset - WAGO I/O-SYSTEM 750 Manual

58 Table of Contents
7.2.1

Example of Determining Gain and Offset

A two-point calibration method is used.
Perform the following steps in WAGO-I/O-CHECK:
1. Select a channel and signal type under Channel settings.
In this example, signal type „0-10 V" has been selected.
2. Enable user calibration under Calibration.
3. Set the value for the calibration offset to "0".
4. Set the value for the calibration gain to "1".
5. Specify the 1st process value.
6. Read the expected output voltage on the measuring instrument.
Example:
7. Specify the 2nd process value.
8. Read the expected output voltage on the measuring instrument.
Example:
9. Insert all calculated values into the respective equations.
You obtain the values for the calibration gain and offset sought as the result.
Example:
10. Enter the calculated gain value ("0.99") in WAGO-I/O-CHECK.
11. Convert the result for the calibration offset based on the process value
resolution:
12. Enter the calculated offset value ("131") in WAGO-I/O-CHECK.
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Process value 1 (y1) = 1 V
At 1 V, the expected output voltage (x1) = 0.97 V
Process value 2 (y2) = 9 V
At 9 V, the expected output voltage (x2) = 9.05 V
Calibration gain:
m = (y2 – y1) / (x2 – x1)
 m = (9 V – 1 V) / (9.05 V – 0.97 V) = 0.99
Calibration offset:
b = y1 – (m × x1)
 b = 1 V − (0.99 × 0.97 V) = 0.04 V
0.04 V / 0.000305 V per digit = 131 digit
WAGO-I/O-SYSTEM 750
750-597 8AO 0-10V/±10V DC
Version 1.0.0
Manual