Connecting to Remote SLC5/03 via Cellular Modem

[rlvmaiden]

Hi,
I made a post about this a little while back but figured I'd remake it as I've made a little progress on it since then.

What I'm trying to do is connect a SLC 5/03 to a cellular modem (http://www.microhardcorp.com/IPn4G.php) via serial cable (RS232) and then be able to access the PLC from my laptop over the internet remotely. I have everything powered up and connected in my office right now, but I can't see the PLC in RSLinx. I have port forwarding set for 44818 in the cell modem, and I can see some connectivity in the modem's Com Port page in the web browser. I have the Ethernet Devices driver in RSLinx pointed at the cell modem's IP, but I'm only getting a yellow ? symbol that eventually gets a red X through it.

Anyone here have any experience with this sort of thing? Any help is greatly appreciated.

 

[Firejo]

Your Ethernet driver in RSLinx isn’t going to recognize a DF1 port that it being bridged via a cell modem. What you need on your PC is serial redirect software. Redirect software creates a virtual serial port that is tied to an IP address and port number (that would be in the cell modem). With the software setup and running you would then point DF1 in RSLinx to the serial port you created via the redirect software. I did this a couple of years ago for a display I build for Automation Fair and it worked OK. The biggest problem I had was that the modem had to be in exactly the right spot for it to be able to get a good enough link to the cell tower to provide the needed bandwidth.

 

[Firejo]

I just read your past post about this topic. Ken (as usual) is spot on this one and is basically saying the same thing I just said. Unfortunately the answer isn’t going to change with the passage of time. DF1 and EtherNet/IP are two different protocols and bridging them isn’t as simple as bridging Ethernet to serial. You need to bridge EtherNet/IP (Allen Bradley’s Ethernet protocol) to DF1 or tunnel DF1. The serial port direct software will give you the ability to tunnel DF1 via the cell modem. The best comparison I can give is that if you are trying to speak to someone and you are on a cell phone and they are on a landline, somewhere along the line the cell connection has to be bridged to the landline connection. However, if you’re speaking English (DF1) and the other person is speaking German (EtherNet/IP) you won’t be able to understand them (and they you) unless a translator is involved.
With all of that said, your question has been answered.

 

[rlvmaiden]

Got it to work, that was exactly what I needed. Thanks a ton! Only issue I'm having now is that the connection is pretty intermittent and I'm having trouble downloading and uploading. I'm guessing this is from poor cell connection that you mentioned?

 

[Firejo]

Either a poor cell connection and/or sharing bandwidth with all of the smart phones and tablets out there on the same tower your modem is on.

 

[rlvmaiden]

Do you know of any solutions for this? Or is this just not a sound way to program remotely? The cell modem has an RSSI of around -65dBm but now I'm not able to see the PLC in RSLinx anymore.

 

[rlvmaiden]

Update:
Played with the settings in the serial redirector, and now it works like a charm. A little on the slow side, but I'm just happy it works.

Thanks for all your help!