Why Am I Losing Decimals When I Read an OPC Variable in LabVIEW?

Updated May 18, 2018

Reported In


  • LabVIEW Datalogging and Supervisory Control Module
  • LabVIEW

Issue Details

I'm reading an OPC variable in LabVIEW and I am seeing a difference of decimals in the Distributed System Manager. Why is this happening?


This problem might be due to several reasons. Below are listed possible troubleshooting steps.
  1. Make sure you are using the correct data type in the Shared Variable Properties in the library in the LabVIEW project.
  2. If you are using Scaling, make sure that the result of the scaling is within the range of the data type selected.
  3. Verify the Display Format of the indicator on the front panel.
  4. If you are reading the variable programmatically using the Shared Variable functions. Make sure the data type of the Open Variable Connection is correct.
  5. Due to the fact that you have to create a library in LabVIEW that will point tp the variable of the OPC Server, make sure that both this variables are of the same data type.
  6. If you created a Shared Variable of a specific representation (eg U8) and during further development expanded it (eg to U16), you may get saturated values over the maximum of the original representation as explained in this KB: Shared Variable Not Updated When Representation Changed


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