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CNV can't find variable on network

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I'm starting my exploration of network variables (CNV) with the example projects.  Excellent examples.

 

Using the Polling project, I have the writer program running on one PC.  On another PC, I have the reader program running.  I modified it slightly so that the network path would be selectable using the Browser example project.

 

The Reader can't find the Writer network variable.  The browser popup (where Reader is running) finds the PC that is hosting the Writer program.  So this is good, in the sense that this verifies both PCs are on the same network and subnet.

 

But in the browser, the tree view can't find any attached network variables.  This seems like a simple problem, but I can't find any.

 

Also, if I run the Reader app on the same PC which hosts the Writer app, this browser popup finds the network variable attached.  So I know that on the same PC, Writer and Reader are working.  Just not over my network (which is kinda the whole point!)

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Hmm, I seem to be getting some hints from the help...

 

It states:


Network Variables <script src="ms-its:cvi.chm::/feedbacklink.js" type="text/javascript"></script> <script src="ms-its:cvi.chm::/variables.js"></script> <script src="/t5/forums/replypage/board-id/180/web.js" type="text/javascript"></script>

You must open TCP ports in addition to UDP ports to configure firewalls and Network Address Translating (NAT) routers to transmit network variables. Starting at TCP port 59110, open one TCP port for each application you run. By default, NI-PSP begins looking for available TCP ports at port 59110 and increments upward until it finds an available port for each running application. You manually can configure the range of TCP ports that NI-PSP uses by creating and editing a logosxt.ini file. For RT targets, you can configure the range of TCP ports in the ni-rt.ini configuration file.


I'm not a networking guru, but I've attempted the following:

  1. Added an Incoming & Outgoing rules to my Writer app computer for both TCP & UDP at 59110
  2. Added an Incoming & Outgoing rules to my Reader app computer for both TCP & UDP at 59110

No change.  My Reader app computer can see the Writer computer, but not the variable name.

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Another data point...

 

To verify my TCP ports, I did some telnet tests.  From the client (Reader) computer, I am able to telnet into the host (Writer) computer at port 59110, no errors.  It takes a little bit of time to connect, but it does work.

 

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Solution
Accepted by topic author ElectroLund

Here you can find to two documents I found useful when configuring network variables scenario:

 

Configuring Software and Hardware Firewalls to Support National Instruments Products

 

LabVIEW Shared Variables through Windows 7 Firewal



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Message 4 of 6
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Thanks Roberto!

 

Your second link in particular helped me get my CNV server visible to my client.  And for my situation, I didn't have to add those other EXEs to my Win7 rules.  I only needed to correct the UDP and TCP ports.

 

All working now.

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I had the same problem but found that the Windows 7 Firewall link above isn't active anymore. The blog it was posted to moved, so here's the new link to help anyone else that has this issue:

 

https://scivision.co/labview-shared-variables-through-windows-7-firewall/

 

Though on that post where it lists which files to add exceptions for, it seems like slashes in the file locations are missing.

 

Also, if you aren't sure how to add port exceptions to the firewall, which I initially wasn't, here's a link explaining how:

 

http://windows.microsoft.com/en-us/windows/open-port-windows-firewall#1TC=windows-7

 

 

It seems like NI should really give a straightforward, step-by-step instruction on how to prevent firewall issues (rather than, say, needing to find it on blog posts that might be impermanent). The NI document is here. Sure, after following the instructions on the blog post, I now recognize that the ports listed in the Shared Variables section are the ones I needed to add exceptions for, but the NI link does not explain that, and doesn't mention the executables at all.

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