global scope of a DAQmx task

[Madottati]

Hello all,

I create and start a DAQmx task inside a dll. The dll is called from TestStand. After starting the task (so inside the dll) I call the "DAQmx Save Task.vi". I see that the task appears in MAX.

Then I try to read the task not in the dll, but just in LabView:

• I can get the InputBuffer size (DAQmx buffer property node)
• I can get the Sample Clock Rate (DAQmx Timing property node)
• ...and on getting the Current Read Position (DAQmx read property node) I get an error: -200983.

The error explanation is "You can get the specified property while the task is reserved, committed or while the task is running".

So what is now the problem? The task runs, as it has been started inside the dll. Inside the dll I can even read the task. How to solve this issue?

[crossrulz]

You are trying to run the task from two different places.  The DLL and then LabVIEW.  That is strickly not allowed.  The talk has been reserved by the DLL.  You need to make the DLL stop the task and release it in order for something else to use it.

[Dennis_Knutson]

Why not do everything in the dll or in LabVIEW?

[Madottati]

Thank you guys. 

We have a step type in TestStand, which has a dll module. It starts the DAQ tasks. There is another dl launched from TestStand, which is a datalogger. Both the datalogger and another steps direct in TestStand have to access the task. 

We already have 4 year old solution for that, it is the usage of Memory Mapped Files, where the acquires waveforms will be stored in a shared memory - visible for all applications. I just wanted to eliminate this. 

Madottati