Digital waveform chart?

[flycast]

I have 17 digital inputs that I am collecting 1000x a second. Each time I collect I get an array of 17 waveforms with one data point each. When I wire this to a digital waveform graph the graph only displays the single data point for each of the 17 DI channels. I want to display the last x seconds of data like a chart does.

How? What is the design pattern? It seems I can't find a "Digital Waveform Chart" in my indicators.

[GerdW]

Hi flycast,

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@flycast wrote:

I have 17 digital inputs that I am collecting 1000x a second. Each time I collect I get an array of 17 waveforms with one data point each. … I want to display the last x seconds of data like a chart does.

How?

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Then you should collect your boolean data in waveforms containing more than just one sample!

What about building waveforms containing "x seconds * 1000S/s" samples?

[flycast]

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@GerdW wrote: Then you should collect your boolean data in waveforms containing more than just one sample!

What about building waveforms containing "x seconds * 1000S/s" samples?

My process is not a fixed length of time. It varies from between 0.1 seconds to 150 seconds. Sounds like I need to initialize a array of digital waveform and then append the data as it comes in.

Thanks for your help.

[flycast]

I am thinking about this a little more. I am collecting the states of air valves (open or closed) by using a DI module (NI 9425). I can collect the data in a number of different types:

1D Boolean

2D Boolean

1D U8

1D U16

1D U32

1D Waveform

It seems to me like I just don't know enough about LabView to make a well informed and wise decision about these different formats. I want to:

• display the data as it is being collected.
• Save the data in a TDMS file after each data set of 0.1 seconds to 150 seconds is collected.
• Check the data for certain out of spec conditions

[StevenD]

Graphs and charts display data from left to right with time or points on the x axis. How are you possibly going to show 17 signals that are all 0 or 1 on that? Best case scenairo you have 8 signals overlap on 0 or 1 (and 9 signals on the other amplitude). Can you show what you expect the end result to be?

[GerdW]

Hi flycast,

---

@flycast wrote:

I am collecting the states of air valves (open or closed) by using a DI module (NI 9425). I can collect the data in a number of different types:

1D Boolean

2D Boolean

1D U8

1D U16

1D U32

1D Waveform

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Well, those different datatypes belong to different acquisition modes…

The 1D boolean reads one sample per channel and gives you a 1D boolean array for all channels.

The other datatypes are used when you read several samples for several channels, giving you 2D data. You get

• 2D boolean array "N channels N samples"
• 1D arrays of other datatypes, where each element can contain the data of several channels (U8/U16/U32)
• 1D array of waveforms, where each waveform contains several samples per channel

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@flycast wrote:

It seems to me like I just don't know enough about LabView to make a well informed and wise decision about these different formats. I want to:

• display the data as it is being collected.
• Save the data in a TDMS file after each data set of 0.1 seconds to 150 seconds is collected.
• Check the data for certain out of spec conditions

---

• You can use any datatype from DAQmx, but you need to adapt the way you "collect" the data in an array.
• Saving to TDMS could be done while you collect the data: is there a reason to wait until you collect a (possibly huge) array after 150s?
• Checking the data can also be done while collecting.

Depending on your requirements you should think about producer-consumer schemes…

[testproggie]

How are you possibly going to show 17 signals that are all 0 or 1?

For those unaware, the "Digital Waveform Graph" handles this quite nicely. Will it be tall? Yes, 17 is still a lot 😉