LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

How to make the waveform static

Hi,

 

I have a simple data acquisition system with only the DAQ assistant connected to a waveform graph to measure the voltage. I am acquiring the data using continous samples mode. However the waveform of the voltage is sweeping.

 

How can I make the waveform static (like using the trigger of an oscilloscope to make the signal display static)

 

regards

0 Kudos
Message 1 of 6
(2,475 Views)

You could put the graph in a case and control the case with a boolean.  If you put the graph in the true case it will update the graph when your control is true.  With the false case empty your graph will no longer get updated data and freeze until you go true again.

0 Kudos
Message 2 of 6
(2,450 Views)

The case structure is dead simple would wokr well but an event structure in a seperate loop would be more flexible. There are a number of ways to grab the current waveform value inside the event case - DVR, single element queue, global variable, or functional global. You could easily expand it to handle other "on demand" events.

Philip
CLD
0 Kudos
Message 3 of 6
(2,441 Views)

Thank you for your response

 

However I don't want to freeze the graph. I am trying to measure the phase of a signal however the signal sweeps on the waveform chart. As a result, the phase mesurment keeps changing as well.

 

 

0 Kudos
Message 4 of 6
(2,411 Views)

I used my friends account A.Abbadi by mistake, But I did the post

 

0 Kudos
Message 5 of 6
(2,407 Views)

How can I make the waveform static (like using the trigger of an oscilloscope to make the signal display static)



To make the waveform static you need to stop sending data to the graph.  There are at least 2 ways to do this. 

 

1)  Freeze the graph which will make the current waveform static.

2)  Set up the task to read N samples and perform 1 read of the N samples, which will also give you static data.

 

Both do the same thing just differently.  With the 1st method you can collect current data and choose when to stop.  With the 2nd method you will just get the amount of data from 1 read cycle.

 

Another way is to set up triggering in max.  Go to Help > Find Examples and search for trigger for examples.

0 Kudos
Message 6 of 6
(2,395 Views)