updating the value from call library function

[Skydive]

Hi everyone,

I am facing a problem configuring a CLF in Labview 2015-64.

I have a dll which is written in C++ (code is available) and need to be called in Labview for indication purposes. The dll should be called once and I need to keep reading the result as it is being updated.

Hier is a sample code in C++, and the goal is to read the sum pointer in LV as it is being updated in dll: (correct me please if the C++ code should be changed!). dll is also here attached.

__declspec(dllexport) void test_sum(int iteration, int waitTime, int *sum)
{
	for (int i = 0; i < iteration; i++) {
		*sum = i + 1;
		Sleep(waitTime); //wait in ms
	}
}

Here is the LV code I have made, it does not crash but just gives me only the last value (here 20). But I expect to copy the memory from the pointer every 2ms in the while loop and showing me the values from 0 to 20! 

Any help or hint is greatly appreciated.

[wiebe@CARYA]

Why is the size 8? An I\U32 is 4 bytes?

You might try not running the dll in the user interface thread. It might block the UI thread regardless the Sleep.

[rolfk · Accepted solution]

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wiebe@CARYA wrote:

You might try not running the dll in the user interface thread. It might block the UI thread regardless the Sleep.

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You can leave the "might" away. Make it:

You MUST NOT running the dll in the user interface thread. It WILL block the UI thread regardless the Sleep.

[Skydive]

Hi Rolf and wiebe,

thank you for the quick response. That was totally correct.

I had this problem before but apparently lessons not learned 😞

Hopefully everything will work when I change it to U8-2D array.

Thanks again.