User calibration
You can use the user calibration to minimize the measurement uncertainty.
During user calibration, the measured values are calculated internally using a correction function. The correction function has the following form:
| YU = GU × XU + OU | YU : Measured value after the user calibration XU : Measured value before the user calibration GU : Gain OU : Offset |
Enable user calibration
The user calibration is disabled in the factory setting. It can be activated individually for each measuring axis. To do this, set the corresponding CoE parameter “Enable user calibration” to TRUE:
Measuring axis | "Enable user calibration" |
|---|---|
Acc X | 8000:0A |
Acc Y | 8010:0A |
Acc Z | 8020:0A |
Gyro X | 8030:0A |
Gyro Y | 8040:0A |
Gyro Z | 8050:0A |
Setting the calibration coefficients
Set the calibration coefficients via the following CoE parameters:
Measuring axis | Offset "S0" | Gain "S1" | "Calibration date" |
|---|---|---|---|
Acc X | 800C:03 | 800C:04 | 800C:01 |
Acc Y | 801C:03 | 801C:04 | 801C:01 |
Acc Z | 802C:03 | 802C:04 | 802C:01 |
Gyro X | 803C:03 | 803C:04 | 803C:01 |
Gyro Y | 804C:03 | 804C:04 | 804C:01 |
Gyro Z | 805C:03 | 805C:04 | 805C:01 |
Factory setting:
- Offset S0 = 0.0
- Gain S1 = 1.0
Value range:
- Offset S0: -223…+223
- Gain S1: 0…2
Calibration Date
This parameter is intended to save the calibration date.
Recommendation: Code the date in the same way as it is coded in the Beckhoff Measurement Technology. For example, 25.08.2015 is coded as 0x15 20 08 25.
(Little Endian; each decimal digit is represented by a hexadecimal digit ("Nibble")).
This coding is unusual, but makes the date directly human-readable in TwinCAT.