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rt Webservice / Shared Variables on cRio

hi guys,

 

i need you help. My system consists of a cRio and a mobilephone (running android). My cRio measures two voltage signals and saves both signals on usb storage device. Futhermore  i have remote panel to check the measurement data running on a mobile computer. But i need a opportunity to check the measurement data on my mobilephone (Android). I tried to solve this problem with the webservice , but i found no way to connect the measurement data with the webservice vi´s. The next problem is the automatic refresh of the webpage. For example, i measure the signal with measurerate of 100Hz, so i need an refreshrate of 100Hz. At the moment i test a vi returning the actual cRio time in an xml page. This works fine. But to refresh the time , i have to refresh the webside.  Can somebody help me?

 

The other way is, to use the network shared variables and connect with the dashboard app. But i don´t know how to implement this in the cRio code.

 

maybe somebody has a good tutorial ?

 

thanks a lot and have i nice day.

 

 

 

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so you want to refresh your browser with 100Hz? Why is this so important for you, you usually cant see this high update rates with your eyes...

so far i know, your browser will also upadate only secondly...

 

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I doubt you can refresh a page at that rate on a consistent basis. Remember, each refresh would have to send a HTTP request. Transmitting from your mobile device, through multiple routers to your cRIO and back again, there isn't a ton of time left over for actually processing the request.

 

Data dashboard might work. To use this simply generate shared variables on your cRIO which correspond to the data you want to read, or generate a web service to publish that data. Shared variables are probably easier to experiment with. The help (http://digital.ni.com/public.nsf/allkb/D9B247551BE7F46A8625795000552CDE) says you can use arrays. I'd recommend buffering the waveform you want to transmit and then storing it in your shared variable or publishing it from a web service.

 

You can also do something similar by making a page which uses javascript to update a graph. This is significantly more advanced, but should work. This code could serve as a starting point for you:

http://digital.ni.com/public.nsf/allkb/D9B247551BE7F46A8625795000552CDE

 

I'm not an expert on this technology, but you might also look into websockets:

http://www.lvs-tools.co.uk/software/websocket_api_for_labview/

http://lavag.org/topic/13777-labview-websockets-and-svg/

 

 

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