Waveform chart from ADC card with external trigger - X-axis timing problem

[saha_k]

Hi

I am new to LabView and this may be a trivial question. I am trying to program the data acquisition from an ADC (CAEN VT1720).  I am using an external trigger for data acquisition and trying to see the waveform after analog to digital conversion. When I run the program, though I can see the Y axis data (in an array), I see no X axis data (timing data). The data array input to the waveform chart is a 2D array and the program shows no error. What may be reason for this?

[Dennis_Knutson · Accepted solution]

A chart or graph will only display actual time if you pass that information to it. If the daq function you use does not create timing timing data like the NI DAQmx functions with the waveform data type, then you have to pass it yourself. One way is to use the offset and multiplier properties and set the start time and dt. The dt is just the inverse of your sample rate. You would also need to set the x axis property to either relative or absolute time.

[mikeporter · Accepted solution]

In addition, note that this technique only works if you are using a constant sample rate. If the sample clock varies (like say it's an external signal coming from an encoder on the end of a crankshaft) you will need to use something based on an XY graph to represent the timing correctly.

Mike...

[saha_k]

Thanks!

It worked..