Issues in ADC acquisition in triggering mode

[rahb]

Hi

I attached the VI here as the reference. In VI, I planned to generate the pulse with some logic, and I want to use this as trigger input for ADC. When DAQ assistant block (along with waveform chart block) is removed, the pulse appears fine at Port 1, pin 2 and 3. When the DAQ assistant is placed (with waveform chart block too), the pulse does not appear at all, at pin 2 and 3 of port 1. I am not sure, why there is the issue in pulse generating when DAQ assistant block is placed. Could you please help me to identify the issue.  

Thanks

Ramesh B 

[rahb]

Hi

I attached the VI here as the reference. In VI, I planned to generate the pulse with some logic, and I want to use this as trigger input for ADC. When DAQ assistant block (along with waveform chart block) is removed, the pulse appears fine at Port 1, pin 2 and 3. When the DAQ assistant is placed (with waveform chart block too), the pulse does not appear at all, at pin 2 and 3 of port 1. I am not sure, why there is the issue in pulse generating when DAQ assistant block is placed. Could you please help me to identify the issue.  

Thanks

Ramesh B 

[Bob_Schor]

So here are some observations;

• I confess to not having the patience to understand the boolean logic-with-feedback that is generating two (identical) Boolean values being delivered to the DAQmx Digital Write function.  It would make an excellent puzzle for a class in Boolean Logic (or How to Write Obfuscating Code).
• You do realize, I hope, that you get only one Digital Write, since you stop the Task without restarting it, so on the second While loop, the task is stopped.  Or didn't you see that?
• Express VIs are meant to do very simple things.  It's NI's way of saying "Let us take all the thinking out of this for you", which means "If it is complicated, you don't want to do it".  DAQmx is easy to learn, and if you learn about Tasks (defined in either MAX or in LabVIEW Project), you can "Learn 10 Functions in NI-DAQmx and Handle 80% of your Data Acquisition Applications" (I think that's the name of the White Paper -- start typing the first six words into a Search engine and see what you find).

Bob Schor

[rahb]

Hi Bob,

I admit that my code is not very clear. But the digital logic which I have shown to you is part of my big project. I just want to mention the problem, that's why I put that small part and mention the adc block along with that. 

• You do realize, I hope, that you get only one Digital Write, since you stop the Task without restarting it, so on the second While loop, the task is stopped.  Or didn't you see that?

Can you clarify this point?

Thanks

Ramesh B

[Bob_Schor]

The (inadequate) picture you posted showed a While Loop.  Inside it, you have two DAQ functions, DAQ Write and Close Task.  So the first time through the loop, you'll write the Digital lines, then close the Task.  Every other time through the loop, the closed Task should do nothing.

Please do us the courtesy of posting your code, not a picture of it.

Bob Schor