Saving and Re-using Offset Null Information for Strain Measurements with the NI 9237 or NI SCXI-1520?

Updated Feb 14, 2018

Reported In

Hardware

  • NI-9235
  • NI-9237
  • SCXI-1520

Issue Details

I used to be able to import calibration information with strain measurements tasks when using SCXI. These settings included the Fine and Coarse potentiometer settings used for the offset null settings. When I try to import these settings using a NI 9237, I receive the following error:
 

Solution

The offset null process occurs entirely in software with the NI 9237. As a result, the hardware calibration parameters such as Coarse and Fine potentiometers commonly used with SCXI are not supported. You can still save and re-use your offset null settings in a similar manner with the 9237 by making use of a different property.

The Initial Bridge Voltage property stores the null voltage value for the channel. It is also updated when the offset null process is executed. You can use this property to save and transfer calibration information from application to application.

To access the Initial Bridge Voltage property, use a DAQmx Channel Property Node. The property is found by browsing to Analog Input » General Properties » Signal Conditioning » Bridge » Initial Bridge Voltage. This property can be seen in the screenshot below.

Additional Information

You can also read the initial voltage value after applying an Offset Null via the same property node. Simply right clicck on the node and find the item Change To >> Read. 

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