Newbie: Logic Analyzer Vi?

[henry99]

I have several digital signals that I want to figure out the timing how they relate to each other and was wondering if Labview has some sort of logic analyzer function?

I want the clock on the top and the signals, A,B,C down the side and the levels 0 or 1.

Anyone point me in the right direction? 

[Hillman]

Hi Henry99,

Thanks for the post and I hope your well! 

Im afraid I don't completely understand your question, could you maybe send a graphic?

So are you aware that there are digital waveform plots?

And im not fairly with the logic analyzer - I assume its outputs wouldn't be graphical - thus what are they?

Kind Regards,

[Coal_Man]

Hello Henry,

I'm not sure what hardware you are using to accomplish this logic analyzer, but the best product you can use for this functionality would be one of our High Speed Digital I/O boards.  If you have the NI-HSDIO driver installed, it includes an example called Logic Analyzer that you might find helpful.  You can download and install the driver from here:

 http://joule.ni.com/nidu/cds/view/p/id/1126/lang/en

Take a look at this VI, it's fairly basic, it acquires digital data at a rate you specify and displays it on a graph.  It also has some triggering capabilities.  What type of data are you trying to capture?  At what rate do you need to capture it?  This will effect what hardware you want to use.  If you are looking at LVDS data, you will want to look at the 656x series of devices that can acquire up to 400Mb/s, there is also the 655x series if you need programmable voltage, and these can go up to 100MHz.  The great feature of these boards is that you can do an onboard hardware compare, which can tell you if your logic is what you expect it to be.  We also have the 654x series that offers selectable voltage at up to 100MHz, all of these work with the NI-HSDIO driver, which includes this logic analyzer VI.  We also offer a Logic Analyzer bundle that includes either a 655x or 654x board and SignalExpress, which will alow you to easily acquire, generate, and store signals.

[henry99]

Thanks for the responses.  I looked at the digital waveform chart and it's exactly what I need.

Are there some example VIs using it that I can find somewhere for a newbie?

I tried collecting digital inputs, set as waveform and then connected it to the digital waveform chart.  However, it doesn't stream as a function of time but rather just acts as a fancy boolean showing either 0 or 1 as the input changes.

How do I set the history so that it scrolls as a function of time and I can scroll forward or backward in time say over 10seconds to examine the data?

I looked in the help and there's supposed to be some history or buffer setting but I couldn't find it.  Thanks again.

[unclebump]

I do this all of the time with OPC server data and the DSC module. I just read the values in as boolean. Convert them to digital waveform and stream them on a waveform graph that resets itself to zero after so many scans. Since I'm using the DSC module, Citadel stores the values in a historical database. I let the real time data scroll in the background and read the historical data for the time period that I want to see. But I'm only looking at 50 or 100ms resolution with this approach. These are 7.0 format files. I use this to catch timing issues with the sequences of our machines. We use a logic format that is scan dependent and at times you can't see what is happening inside the programming software.

[unclebump]

Here are some images of the historical data as it is read back into labview.