Ethernet Port Numbers?

I'm using both RSLinx and some third party stuff to talk to PLC-5's and SLC-500's via ethernet. This all works fine as long as everything is on a LAN.

I've tried making the connection over the internet with access to the network which the PLC is on being through a router. I have not been able to get this to work. I suspect the problem is that the router is not allowing communications except on certain ports. And, I can't figure out what port or ports are being used. I see no place in either RSLinx or in the 3rd part software to specify any port numbers so I assume it's hard-coded somewhere.

Does anyone have any experience in this area that could give me some guidance?

Thanks.

This might be able to help you with your port number question. This was posted by Jiri Toman.

Ethernet/IP uses port 44818. Set up your router to ignore other Port No's. What you have not stated is what type of Ethernet/IP you are using. Is it just PCCC encapsulation or is it CIP? If you use CIP you need to survey the network with RSNetworx for Ethernet and in this case you would need to have a guaranteed bandwidth to achieve
deterministic network operation. (producer/consumer). Ethernet/IP uses TCP/IP not UDP so I don't understand all this talk about multicast messages??

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The question that I would like to ask is what router are you using? We are going to setup our network about the same as you and I've been looking for suggestions for a model of router.

plc.doctor said:

The question that I would like to ask is what router are you using? We are going to setup our network about the same as you and I've been looking for suggestions for a model of router.

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Right now, I'm trying to get this to work on my office LAN which is connected to the internet via a LinkSys BEFSR41 router and a cable modem. It's a NAT router - in order to get any inbound traffic through it, I need to specify the port number and the IP address of the computer or PLC to which the data stream will be forwarded.

I've used a BEFSR41 at my apartment connected to an AT&T cablemodem to provide examples of Internet access to ControlLogix and PLC5 systems.

For PLC-5E or SLC-5/05, you need to forward TCP Port 2222 to the IP address of the controller.

For ControlLogix, you need to forward both TCP and UDP port 44818 to the IP address of the controller.

The BEFSR41 will only forward an external Port to one IP address, so you're only going to be able to get to one controller at a time from the outside. You would have to administer the BEFSR41 remotely every time you wanted to talk to a different controller.

The BEFSR41 also provides no security on the ports it is forwarding through it's firewall, so I would not be confident using it for anything but demonstration purposes.

I don't own any VPN appliances and don't have the $3000 to buy one to play with, but one of my customers has had very good success with SonicWall SOHO3 products.

One addditional thing; make sure you put the internal IP address of the BEFSR41 in the "Default Gateway" setting of your PLC-5E or SLC-5/05 controller's port configuration. By default this is 192.168.1.1. That allows the PLC to correctly reply to the router, but isn't required for internal-on-the-LAN connections so it's easy to miss.