Generating data with 6722 and reading it back with 6221 - visualizing it with a virtual oscilloscope

[db2nc]

Hello,

I generate an analog signal with the 6722 and want to read it back with the 6221. The results should be shown in virtual oscilloscope. My problem is that I have no idea where to put the signal-graph and which type I should really use. The second problem is that I have no idea how to choose a good time scale and where and how to define it. Finally, I like to see the image which I get on the real oscilloscope with the 6722-generated data on the virtual oscilloscope with the 6221. In the first step, the oscilloscope should have no trigger (just running mode) as the 6221 has only a digital trigger.

At the moment I have a for-loop which generates the signal by using a sequence. Now, the question is where to put the signal-graph and which settings I should use for reading back the information (1 Sample, continuous etc).

Thanks,

Verena

[Dennis_Knutson]

I don't think there is a single piece of that image that shows correct programming. The for loop, local variables, the single sample write and the sequence structure are all wrong. Have you looked at any of the DAQmx example programs? You can create a waveform (sine, triangle, square, etc.) and do a continuous write. The waveform data contains timing information. To do a read, a continuous setting for that will also work. You can put everything in the same while loop.

The continuous read and the continuous write are both well documented in the examples. It looks like you are just making things up as you go along.

And why are you even using two different DAQ cards? The 6221 can do analog input and output.

[db2nc]

Thanks for the reply, however, it does not really help me as I did not got along with the example and sometimes did not find examples at all. Perhaps you can give me the correct examples which you are thinking of.

The reason, why I use 2 different cards are historical ones. And e.g. I have only 2 analog inputs in the 6221 and more in the 6722. Finally I probably need more.

[Dennis_Knutson]

There are several. Look for the basic 'continuous' ones without triggering, etc. I'm not on a pc so I cant provide specific names. Use the 6221 as a hardware filter when you do the search.

You are wrong in your terminology. The 6722 has only analog outputs.

[db2nc]

I tried another strategy (see VI). However, I am still noch able to produce a analog signal (upper loop) and read it back (lower loop) on an analog input and visualize it. Where do I have to put the read-back loop? Which are the settings?

Info: Using Labview 2009

[M_LeFeu · Accepted solution]

hi db2nc, 

here's a link to an example from our community. It shows you an example with which you can generate a signal on an output and acquire it on a different input.

I think that is what you want to archieve. 

Synchronized Analog Output Loopback to Analog Input

regards

Michael