No such thing as a Digital Chart?

[Tobin]

Hi,

I'm gathering signals from a USB-6255. I have a collection of analog waveforms and some digital waveforms. I'm using the Waveform Chart for the analog signals. The update mode is set for Strip Chart. I want to do the same thing for the digital signals, but I can't feed the digital waveforms into a Waveform Chart. I can only feed them into a Graph (which doesn't have the Strip Chart mode for updating).

Even the Mixed Signal indicator is a Graph. Ideally, I'd like a Mixed Signal Chart indicator.

Any suggestions on how I could create the same effect as a strip chart for my digital waveforms?

Tobin

[Kameralina]

Hello Tobin,

Usually when you connect the output of a digital signal to a Waveform Chart, you need to place a "Convert to Dynamic Data" node in between to make sure that the signal (data) has the correct format.  When you use the DAQ Assistant, for example, and wire it up to the waveform chart, it places this node automatically.

Please double check, since I am myself able to output a digital signal to a Waveform Chart.

Have a great day!

[Tobin]

Hi FieldKam,

I've tried your suggestion and it does not work for me. I'm using LabVIEW 8.5 professional development system (on WindowsXP). I'm using the "Digital Waveform", not just a digital signal or an array of booleans.

When I connect the "Convert to Dynamic Data" node, I am prompted to choose the type of incoming signal. I've tried each of the choices, but nothing clears the broken wire. The closest that I get is the broken wire message "You have connected two terminals of different types. The type of the source is 1-D array of Digital Waveform. The type of the sink is 1-D array of Waveform(DBL)".

Below is a picture of a the data type along with its representation in a Digital Waveform Graph indicator. Again, I'm looking to use a strip chart to view these signals.

[_orko_]

Since you are using an array of digital waveforms with only one signal in each waveform (this is what it looks like from your screenshot), I think you would want to combine all the signals into one waveform so you could use the VIs in the digital waveform palette (for instance the digital waveform to boolean array would work nicely here). Something like the attachment below...

Message Edited by _orko_ on 04-15-2008 04:11 PM

[Tobin]

_orko_,

Thank you. That does work for me.

I'm wondering if some of this work could be taken care of in the DAQmx Read vi. There are a lot of choices when configuring it. Maybe I made the wrong choice.

My DAQmx Read vi is configured in the following way: Digital -> Multiple Channels -> Multiple Samples -> 1D Waveform.

Thanks again.

[_orko_]

I'd probably have to know a little more about how your DAQ channels/tasks are set up.  However, if you are taking single sample readings from multiple channels then perhaps you could use Digital->Multiple Channels->Single Sample->2D Bool (NLines per channel)?

[Tobin]

_orko_,

Changing my DAQmx task to output a boolean array looses the timestamp information of a waveform.

My original goal was to have my analog waveforms and my digital waveforms in a strip chart with correct timing relationships.

There is no "Chart" indicator that accepts digital waveforms.

I came up with a way to use my digital waveforms in a strip chart. I take the Y components and convert them to boolean array. Then I convert the boolean array to dynamic. Then I convert from dynamic to an array of (analog) waveforms. Finally, I replace the t0 and dt of the new waveform array with the t0 and dt of the original digital waveforms and I offset each waveform a little bit so they don't overlap in the strip chart.

Attached is an image of this part of the block diagram.

Thank you for your suggestions.