Delay in remote panel chart

[andypy]

Hi,

I am currently developing a scope that displays live data from a test rig. The scope is accessible via remote panels. Tests normally run for many hours at a time, when monitoring the scope after several hours of running I notice that the data on the chart displayed via the remote panel is not in sync with what can be seen on the actual 'server' vi. The delay also seems to be getting bigger as time goes on. I also display the current data points in an indicator; however these seem to be in sync and 'current'.

The scope is part of a built application and I am using labVIEW 2012 f3 to develop it.

I know that there is an issue with synchronizing front panel appearances when using remote panels in built applications but I think I have got around that by re-applying panel changes when a new client connects. Also on every execution of the VI, I defer panel updates make all my updates to controls including the chart in question, force draw the chart and then re-enable panel updates.

I would really appreciate if anyone that has experienced this sort of issue could share a possible solution/work around.

Thanks in advance.

[P@Anand]

How do you transfer the data from the remote system to your work station? Can you show us the code if possible to get a better view of the issue.

[andypy]

Hi,

Unfortunatley i do not have the code to hand at the moment.

A little more information on the system itself. The computer running the 'server' application acquires all the data via various instruments on the test rig.

The client connections are done via a web browser so the data is transfered via labview web server protocol im assuming. I have also tried connecting labview remote panel connection tool also and i still have the same issue.

I hope this answers your question.

Thanks.

[P@Anand]

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@andypy wrote:

The client connections are done via a web browser so the data is transfered via labview web server protocol im assuming.

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I don't think so. BTW what do you mean server vi, how are you running the server vi. The remote system you said is it running in sync with RT and you are monitoring through web server? Or is that remote system running on it own, meaning without any RT the data acquisition happens in that system itself? I am trying to understand what is happening

[andypy]

Hi,

There is no RT involved. The application that collects the data is running on a windows 7 system. Clients connect to the remote panel over the network.

[P@Anand]

Looks like you have to dig into the code and see whether you are running the data acquisition and display loop out of sync. Try to get the code and see how things are handled otherwise its very difficult to come to a conclusion.

[andypy]

The data on the actual scope on the running application is in sync, no problem there. However when i view the same scope via a browser remote panel and compare them side by side, plots on the remote panel are delayed. This delay get s bigger and bigger the longer the application is being run. Does that make sense?

[P@Anand]

I believe the rate at which the data is uploaded to the web service is not equal to the rate at which you are seeing the data real time in the remote syste. Since I am not good with web service you may check the resource available in NI website to nail down the issue. 

[andypy]

That sounds like whats going on. Ill try digging around to see if i can find anything. Ill post back here if i find anything.

Thanks for your help

[P@Anand]

Just for understanding, Do you have a runtime engine on the client PC from where you are monitoring the system using browser?