Can/do network streams use an ethernet cable between RTT and host?

[Shiv0921]

I think this must be simple, and that’s why I can’t find it explicitly said anywhere, but lots of googling still hasn’t helped.

I have a cRIO-9045, which will mostly run headlessly. Occasionally a user will need to connect a PC to view the UI and put the program in maintenance mode. They’ll then disconnect and the program will keep running. (pretty standard)

The company we’re working with want the cRIO to have a permanently connected ethernet cable in the installation, and the user will occasionally come along with their laptop and connect to the other end of this. I feel like this can’t be how things are normally done, but we need to meet ATEX (explosion-proof) standards and they feel it’ll be easier or something.

This is where I’ve realised I’m not sure how the different networking methods line up with the hardware setup. I’ve been under the impression that standard way to connect remotely doesn’t use a cable between the rio and host, and *somehow* they connect across a network and find eachother using the IP addresses of each, but clearly I don’t really understand how this works.

So I have a couple of questions:

• When we’re talking about network streams, or TCP, do these assume a physical cable connecting the two or not? Do I need to do something differently to the examples (such as this) because I have a physical connection?
• Currently, if I want to deploy to my cRIO I use an ethernet cable, but the connection occurs seemingly automatically. In an exe, would I just need to poll for this connection? Is that possible?

It would be convenient to use the examples as they are given, but I can’t tell whether they are geared towards my setup or not. Thanks in advance for any help. 

[crossrulz]

A cRIO does not have a built-in WiFi, so you will needed a cabled Ethernet connection to something.  That could be a wireless router you can connect to via your laptop.  I just use a direct cabled connection myself.

[Shiv0921]

That makes sense. Can I just have it connect directly to a laptop, which would be connected to its own Wifi? Or will connecting to a router be easier? The company didn't like the idea of having Wifi involved anywhere near the cRIO, but I suppose the cable can lead to a router rather than a PC if that's the more logical approach.

For this setup, do I still just use the standard network streams approach of defining a writer and reader endpoint and giving one of them the url of the other?

[crossrulz · Accepted solution]

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@Shiv0921 wrote:

For this setup, do I still just use the standard network streams approach of defining a writer and reader endpoint and giving one of them the url of the other?

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A network connection is a network connection.  Your software does not care if it is wireless or Ethernet or how many routers are in between.

[Shiv0921]

Oh right wonderful! So basically there's a variety of ways in which you can establish a network connection (be that wifi or ethernet) and once that connection is established the software side is always the same?

[Bob_Schor]

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@Shiv0921 wrote:

Oh right wonderful! So basically there's a variety of ways in which you can establish a network connection (be that wifi or ethernet) and once that connection is established the software side is always the same?

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Yes, that is basically correct.  I've done some work with the myRIO (NI's RIO for students) which has both WiFi and a USB Cable that "acts" as an Ethernet connection (it uses TCP/IP and has a fixed IP of 172.22.11.2).

Talk to your Networking people.  They should be able to help you determine a suitable fixed IP for the cRIO (I think you can set this IP through MAX), and work with you to set up a direct "wired" connection between your PC and the cRIO.  If they are worried about "security", you should be able to get tthem to assign your cRIO a fixed IP in their range of devices.  You can explain to them that you will not plug the cRIO into the Network until you are ready to "talk" to it with your LabVIEW program, at which time it will be tied to (and responding only to) the Network Streams coming from your Laptop (which I'm assuming is getting to the network via WiFi).

Bob Schor