Multiple channels, multiple waveform graph

Hello, there! I am trying to read four signals from four channels on DAQ device. I need to show the first two signals on one diagram and the other two on another diagram. So I wrote a simple VI as I attached. It gives me an error message like the picture I attached. Does anyone know how to debug this VI? I have come up with some very stupid idea to solve this problem, I can wire all this four AI Voltage VI together then go through Timing VI, then Logging VI, then Read VI, then I can connect the data terminal of this Read VI to an Index Array VI, so that I can do the following as the third Pic I attched. I have not tried this yet, but I want to find out some better method. (Maybe like the VI I wrote, it is very intuitive for people to understand)
Attachments:
4 voltages in one task.vi ‏52 KB
message.png ‏17 KB
my last way to solve the problem.png ‏9 KB

Hi,
We need more information on detail of the DAQ device in use? I suspect this error could be due to sharing of single onboard clock.
However, If all the channels could be coupled into a single task (This should be possible since there are not configuration difference between acquisition for different channel)
Then you could use the Simple Delete from Array Function with Index=2 and length =2 available to seperate the waveform array and display them on two seperate graph Indicator. (attached modified vi)
Attachments:
4 voltages in one task.vi ‏46 KB

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Display multiple channels on waveform graph

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Attachments:
acq code.jpg ‏119 KB

Turn off a single plot of a multiple plot waveform graph

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I think you can use "active plot" together with "plot.visible"
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On 18 Feb 2004 03:28:49 GMT, [email protected] (Computerman74)
wrote:
>>
>>I have a multiple plot waveform graph (4 plots). I want to turn off
>>one of the plots, say plot 2. Is this posible from the graphs
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>>Cheers,
>>Wayne
>>
>>
>>
>>
>>
>>
>
>I would love to know if this is possible. I have been trying to figure i
t out
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Display multiple Waveform-Graphs on a separate Frontpanel

Hi there,
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Thanks so far,
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3. GridOfWindows displays the desired grid of graphs in separate windows, but they don't stick together
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Attachments:
multigraph.llb ‏136 KB

Multiple waveform graph

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Attachments:
graph-chart.vi ‏15 KB

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Please Mark the solution as accepted if your problem is solved and help author by clicking on kudoes
Certified LabVIEW Associate Developer (CLAD) Using LV13

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Multiple channel waveform output using a 6711 board

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Attachments:
aoex7.cpp ‏20 KB

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Attachments:
aoex7.cpp ‏20 KB

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Hi there;
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Greetings

Multiple Waveform Graphs

Dear group,
I have a user panel that contains three waveform graphs in which only one
graph is visible to the user. All three graphs plot the contents of the same
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graphs contain a plot of the array. The user selects whether to display
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Thank you in advance,
Luca

My apologies, it should say graph instead of chart.
Luca
"Greg McKaskle" wrote in message
newst5oc.86746$[email protected]..
>
> > In the case of the former do I use much more memory or slow down the
> > execution of my program more than in the case of the latter?
> >
>
> In part of your question you call the control a graph, and in other
> parts a chart. The answer depends a bit on which you are showing and
> hiding. Graphs only show the most recent data written to them, charts
> retain and show history.
>
> Neither the graph or chart will have much overhead receiving data while
> hidden. On the otherhand, it isn't zero either since they will at least
> be doing a data copy so they can draw with correct data wh
en shown.
>
> It will be easiest to send the data all the time since otherwise, you
> will need to send fresh data when showing the graph. If dealing charts,
> not only will you need to update the current data, but the history will
> be old. You will need to clear or write the history.
>
> If it doesn't cause a problem, write to them always, but if you can
> measure a problem or have spare time on your hands, add code to make the
> update conditional and deal with the data when being shown.
>
> Greg McKaskle
>

Data acquisition from multiple channels.

Hello
Right now, I am able to acquire the signal from a single load cell and display it.But I would like to know of how to acquire acquire signals from two load cells simultaneously.I am using Labview 6i and I am using AI S-Scan with AI config to acquire the waveform.It would be of great help if you could suggest a simple method to acquire the signals.
PS: Please find the attached file used for acquisition from a single load cell.
Looking forward for your reply.
Manasa
Attachments:
test 4.vi ‏102 KB

Hi Manasa,
If I understand what you are trying to do, it is relatively
straightforward to configure your application to acquire data on two channels.
I was unable to run your vi as it was missing some of the subVI’s
from your application. However, your
attachment was sufficient to see what you are trying to do.
Here is how to add channels:
1.
In the I/O Channel Constant, you can add
additional channels by using a comma or a semi-colon. For example, to scan the first four channels
you would put 0:3 in the constant (see attached screenshot ChannelConfig.jpg). To scan the first and third channel you would
put 0,2.
2.
The AI Single Scan VI will now read from
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configure the output of this VI for viewing by first putting the data into an
array using the Build Array VI. It can
then be plotted in a waveform graph. (see attached screenshot ReadtoGraph.jpg
and WaveFormGraph.jpg)
Just a few notes about “simultaneous” sampling:
Most of the NI data acquisition cards have a multiplexer
between the various input channels and the Analog to Digital (A/D) converter
creating a very small delay between each channel (usually ms range or
smaller). NI does make several data acquisition
cards that can perform true simultaneous sampling, meaning that there is an A/D
converter for each channel.
For the large majority of applications, the small delay
between channels is negligible.
Jared T.
Attachments:
ReadtoGraph.JPG ‏21 KB
ChannelConfig.JPG ‏288 KB
WaveFromChart.JPG ‏61 KB

DAQmx Create Multiple Channels

I have downloaded the NI Bridge-Continuous Input Program and am trying to modify it slightly to allow for multiple Wheatstone bridges to be connected. Currently, it has the option to connect to a single channel but not to acquire information from multiple channels simultaneously. All of the information in terms of shunt calibration, bridge information, and waveform graph output will remain the same. Ideally, the program will show the largest value in the final waveform graph but it's fine if it shows separate graphs for each of the two inputs. I have been playing around with it without much luck although if I start from scratch and use the DAQ assistant I am able to get the information without trouble. Any help would be much appreciated.
Solved!
Go to Solution.
Attachments:
Force Measurement.vi ‏96 KB

Actually you are 99.99% of the way there.
You just need 4 characters
The Name filtering on that control is even properly set to allow multiple selections so just shift click the second channel
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Multiple channel sampling and write file

Hei,
I wrote a interface which is supposed to allow me to plot multiple channel and write all those datas in a file ; The problem is that :
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I have attached the vi, I don't understand exactly where those problems are comming from and how to solve them easily.
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Attachments:
project.vi ‏207 KB

Hi thanks those tips. In fact I had solved those problems mentionned above ; I have alomst finish my interface except that I am trying to write all my datas in a file , in column (all channels) and create a first column at the time (maybe from the sampling time). The problem is that I don't know the output fomat of the "analog 2D DBL" vi and it seems that my way of writing datas time step per time are not right. have you already see this kind of used (analog 2D DBL)? I am using a PCI-6229, and DAQmx 7.3 Drivers
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P.
Attachments:
project_acquisition.vi ‏338 KB

Acquiring Analog Input from Multiple Channels in Labview

Hello,
i am working on a VI where i need to acquire signals from multiple channels in Labview using NI-9129.Initially i want to acquire contineous input signals (voltage and current) and display it on the graph.
Having looked at forum and Labview examples i tried to make an initail VI but i am not sure if the setup i made needs any modification to serve my purpose.I am fairly new to Labview software.
All i want is
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3.Perform some basic calculations like MAXIMUM,MINIMUM and AVERAGE values of voltage and current.
4.Log the data into excel file
I have attached the VI i made so far.i need abit of advice if i am moving in the right direction or not.
Thank You for having a look at my question.
Attachments:
Voltage-Current VI.vi ‏81 KB

Engr_tech wrote:
i think i already have the tdms for data logging.as far as the tdms data logging is concerned,when i enable the logging mode to "read and log" the data logged inside the excel sheet would be seperate for current and voltage.?
Is it practically possible to acquire data from 4 different channels and plot them.if yes,then am i right to assume that all i need is to modify the current VI for four channels having all of them in parallel.
Yes, you are logging directly to a TDMS file. This is definately the best route for data logging from a DAQ. The currents and voltages will show up as different channels in the same group.
To add more channels, just add them to your DAQmx task. The logging will handle it with no issue. Your calculations will also a little work to add the extra channels. Same for the graphs, since you are using seperate charts.
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DAQmx multichannel read error. DAQmx believes there are multiple channels in my task.

Hello,
I recieve the appended error message when attempting to use DAQmx Read in my VI. LabVIEW is telling me that I am attempting to read a single channel when my task is configured for multiple channels. However, as you can see in the task configuration pane, that is not the case! If I attempt to use DAQmx Read to generate a waveform with multiple channels, the VI executes without error but I do not want a 1D waveform array.. Any tips?
Regards,
Steve
Solved!
Go to Solution.
Attachments:
multi_chan_errr.JPG ‏42 KB
channel_Vin.JPG ‏108 KB

This is exactly why I ALLWAYS hide my DAQ Tasks inside a "Resource Module"
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Jeff

Multiple channels, multiple waveform graph

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