live graph display

[Zexi]

Hi,

I am using the attached labview VI to control some output voltages and record some voltage signals at the same time. I am using PCI-6713 and PCI-6032E for the application.

Usually I set the control "inj cycle" (on injection panel) to be 1, and as you can see the period time is 420 seconds (7 minutes). Cause one run is 7 min duration. At the same time I need to record voltage signals from 2 input channels.

The thing is the graph window would show nothing until the run finishes. What I want to see is as the run is going, I could see the voltage signals on the graph lively (say the graph is updated every second or every 10 seconds). How can I do that?

Thanks,

Kevin

[devchander]

Could not open and see your vi as I do not have 8.2 version of LabVIEW  on my system

Use a chart instead of a graph and see if it solves your problem

Message Edited by devchander on 09-27-2006 03:10 AM

[Zexi]

Here I attack one file of labview 7.1 version.

Don't think the chart will work if the graph will not. I think probably I have to change something in the code, because there was a loop and the reason why it won't display anything till the run time finish is because it won't display until one loop finishes.

So I'd probably need to code it some other way. Hope could get some help.

[Jesse_O]

Zexi,

I have taken a look at your code, and for the DAQ Read VI you specify 42 000 samples.  Since you are acquiring at 100Hz it takes 420 seconds to acquire that data.  This read VI will wait for the specified number of samples to return.  If you look at the DAQ shipping example called Cont Acq&Graph (buffered).vi typically located

C:\Program Files\National Instruments\LabVIEW 8\examples\daq\anlogin\anlogin.llb

In this example it shows you how to continuously acquire data.  In the loop the DAQ Read VI specifies only a small number of samples.  They are read into the LabVIEW application and displayed.  This is different than your application.  You specify to read in 420 seconds of data at once instead of in smaller chunks.

On a side note, your application has been developed in Traditional DAQ.  For future applications with these devices, or new ones, you might want to consider using NI-DAQmx since Traditional DAQ does not support any of the new Data Acquisition products such as cDAQ or isolated USB devices.

I hope this helps,

Jesse O.
Applications Engineering
National Instruments

[Dennis_Knutson]

Since you used traditional DAQ instead of DAQmx, I can't run it because I don't have the hardware but I'm not sure I see the problem. First, you don't have a single graph in your program. You have two charts. The chart called 'acquired data' is inside a loop and will get updated with every iteration of the loop. The chart called 'output data' will get updated as soon as the file is read/parsed and never again since the whole VI will stop when the while loop terminates. Since you've hidden the run continuous button, I don't think you are running it that way but are you calling this whole thing as a subVI and the problem you are seeing is with updating indicators in the main program? If that's the case, then that's an entirely different issue. That can be easily solved with using a control reference but please explain how this VI is being run.