Shared Variable Initial Value Has No Effect in LabVIEW DSC

Updated May 3, 2018

Reported In

Software

  • LabVIEW
  • LabVIEW Datalogging and Supervisory Control Module

Issue Details

I created a shared variable in my LabVIEW project. When running a VI which is reading the shared variable, I am getting warning -1950679034 since the variable has no known value at the beginning of the execution.
Thus, since I have installed also LabVIEW Datalogging and Supervisory Control Module (DSC), I set an Initial Value for the Shared Variable as shown in the following image:
 

However, when I run my LabVIEW application again, I still get the same warning and I am not reading the value which I set as Initial Value from the shared variable. Also, looking at the shared variable in Distributed System Manager, I still get No Known Value.

Why is Initial Value property of my shared variable not working? How can I set an initial value in order to avoid the warning?
 

Solution

The behaviour you are getting is expected: the initial value only works when you create the shared variable for the first time. If the variable already exists and you deploy it a second time after setting the initial value, the initial value will not be set to avoid the risk to overwrite the variable's current value with the initial value.
In order to have Initial Value to work correctly, you should:
  1. Undeploy the library containing the shared variable by right-clicking the library in the LabVIEW project and selecting Undeploy
  2. Set Initial Value property for you shared variables by right-clicking the variable and selecting Properties » Initial Value
  3. Deploy the library again by right-clicking the library in the LabVIEW project and selecting Deploy

In this way, when reading the shared variable again, you will get the expected value.
 

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