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unexpected loop behaviour with asynchronous call

I am having trouble with loop behaviour when using an asynchronous call.




I am building an application to record simultaneously temperature (NI USB-TC01 thermocouple), displacement (DC voltage, read from an Agilent 34401a) and resistivity (using a Keithley 2400 sourcemeter).


I am using a voltage sweep function on the Keithley 2400 to alternate current direction in a sample and measure the voltage drop - this is a common technique for eliminating thermal emf from resistance measurements. But what you need to know is that I set the number of current cycles I want and then wait for the instrument to measure and return the meausurements - up to 50 samples, which takes nearly 30 seconds. With the other two measurements, I have to programmatically call a measurement vi for each sample I want.


I have set up my application to asynchronously program the resistivity measurement and then wait for the response, and I want to in parallel measure temperature and position until the resistivity is done. I then want to record the mean and standard deviation for each signal. I used an event structure to interrupt the temperature and position measurements when done.


The problem I am running into is that after the first resistivity measurement is completed and I go to do the second one, the loop that measures temperature and displacement only runs twice, so I only get two samples, regardless of how many resistivity samples I want to collect. For example, if I want 50 resistivity samples at a time, the first iteration will measure rougly 40 samples of temperature and displacement, but any subsequent iterations will only measure twice.


I know this is probably overwhelming to understand the operation, but can anyone help? I have attached my code ('Delatometer') as well as a test vi I built that uses the same structure but has no interactions with instruments ('asynchronousCall').



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I forgot to mention...the test vi that I uploaded executes as expected, so I am thinking that maybe its an issue with the instrument calls? I also found that if I run the Delatometer program in 'highligh execution mode' it runs properly, and it is my understanding that in 'highlight execution mode' there is no multi-threading.

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Have you tried changing the timing settings? And as you say, test if changing the instrument calls may be another good step.


Have a good day!

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