214 GDS Helpsheet - Change, update or create transducer calibrations in AdvDCS V2-based systems
Software
AdvDCS V2
Change, update or create transducer calibrations in AdvDCS V2-based systems
This helpsheet explains how to change, modify or create a transducer calibration in AdvDCS V2 systems using the calibration wizard.
Transducer calibration window
To change, update or create a new calibration for a transducer, open the transducer window by clicking on the transducer name in the Object/Hardware Display window.
In the image, for example, we open the Load Cell transducer window.
Select the Calibration tab. The transducer window shows the calibration applied to the selected transducer.
The figure on the right shows, among other parameters, the Sensitivity and Offset parameters, which are associated with a Linear calibration. Other calibration types can be used, for example:
Table-based calibration
Polynomial calibration
Calculated calibration (not modifiable by the user)
CalibrationNone, which provides the raw reading of the transducer without any modification.
If you need to switch the current calibration for a different one already existing, create a new calibration from scratch, or modify or update the current calibration, press Change/Modify Calibration.
If the button is greyed out and cannot be pressed, this means that the calibration has been locked by GDS. In this case, contact support@gdsinstruments.com and ask for that parameter to be unlocked.
Select calibration file
After pressing the Change/Modify Calibration button, a new window opens with a list of calibrations stored in the device.
This option is also the one that needs to be selected if you wish to create a new calibration from scratch without modifying existing ones, for example when adding a brand new transducer to the system.
From here, you have the following options:
Select a different calibration without any modification
In this case, select the desired calibration and press OK. This option is usually chosen when switching between transducers on a particular input channel. For example, a system may come with 2 different load cells with different full-scale values and this option allows to select the appropriate calibration for the load cell being used at the moment.Create a new calibration
By pressing Add New Item, a new empty calibration is generated. Press OK to go back to the transducer window and manually enter the calibration parameters. If you prefer to perform a point-to-point calibration, click onView/Modify Selected Calibration to open the calibration wizard.View or edit an existing calibration
Click on an existing calibration and then press on View/Modify Calibration. This will open the calibration wizard. The wizard will populate the data with the last user-performed calibration data. Factory calibrations do not provide any calibration data points.
The Calibration Wizard
The Calibration Wizard can be used to populate and inspect the calibration data points. Linear and polynomial regressions are generated automatically by the wizard.
This section will detail the steps to follow to generate a new point-by-point calibration using the calibration wizard.
Info panel
In this panel, you can set a custom name for the calibration and an optional description. The former could be used to identify the type of transducer this calibration points to, whilst the latter could be used to store the serial number of the device and any additional information. The Type combo-box shows the type of calibration (e.g. linear, polynomial, etc.).
Add or modify calibration data points
Data table
Below the info panel, on the left, sits the calibration data point table. It contains data points collected during the calibration procedure and it allows the manual editing of the calibration points.
The field Applied refers to the calibrated units the transducer is currently subjected to, e.g. 1 kN or 50 kPa. The field Read is the raw reading of the transducer, which most often is in units of mV.
The figure on the right shows an example with 3 data points. The Applied, Read and Use? fields can be modified.
Data insertion panel
A new data row can be added by manually inserting data in the blank row at the bottom of the table or, preferably, by using the Applied Value and Read Value input box shown in the figure on the right.
Press Insert to add the pair of applied and read value to the data table.
The Autoread button, if enabled, automatically feeds the Read Value box with data collected automatically by the device. This allows for a fast point-by-point calibration procedure.
The Full Scale Value field is used to set the full scale value (in mV) of the transducer which will be used by the system to select the optimal input stage configuration for maximum accuracy. The Effective Full-Scale field shows the current full scale of the input.
To delete a calibration data row, select it and then press Delete Row. Alternatively, you can un-set the checkbox under the Use? column to preserve the calibration row; in this case, the data row will be ignored when generating the final calibration.
Graph and regression results
At the bottom of the calibration wizard, you will find the graph and, where applicable, the regression results from the current calibration points. For a linear calibration, the results indicate the slope (which will determine the sensitivity of the final calibration), the intercept (which will determine the offset), the maximum error from linearity and its associated data point, and the R2 coefficient which determines the goodness of the linear fit (the closer to 1, the better).
For polynomial calibrations, this panel also shows the polynomial order chosen for positive and negative raw values.
Import/Export calibration
Calibration can be imported from file by clicking on Load from File. Supported formats are .ccal and .xlsx (both generated by a previous calibration on AdvDCS devices or provided by GDS staff).
To export the calibration in Excel xlsx format, click on Export to File.
Save calibration
Once finished with the calibration process, click on Save to save and apply the calibration to the transducer. The transducer window will show the new calibration parameters, which can be manually edited if needed. Calibration data points will be automatically saved to disk under C:\GDSLab\Calibration Files\ with the following file name format:
[TransducerName].ccalSelect the new or updated calibration
After closing the Calibration Wizard, select the new or updated calibration and click Ok.
The new or updated calibration should show in the transducer window. You can edit any calibration parameter without affecting the saved calibration file.