CLX networking question

[jmtricker]

Hi Y'all,

I know next to nothing about network communication. My question is I have a network that I use to access the line PLC's, but a lot of those PLC's have private networks attached to them with private networks. Is there any way to tunnel through the line PLC's to access the private PLC's? I don't want to have to drag a laptop out on the floor if I want to make a change, or even troubleshoot.

Thanks in advance,

Joe T.

 

[harryting]

If I interpret your question correctly. Sounds like you have a lot of vendor provided automation "islands", each with their own IP address scheme. You wish to connect them all together for ease of maintenance and/or data exchange.

Two typical options here,

1. Change their IP addresses to bring them into the plant's addressing scheme.

2. Use some kind of NAT (Network address translation) device to give each of the island a "public IP" that fits into your plant's addressing scheme.

 

[Ken Roach]

Is there any way to tunnel through the line PLC's to access the private PLC's?

It depends on the make and model of the controller.

Allen-Bradley ControlLogix, for example, can route messaging and engineering/HMI traffic from a network module to the backplane and back out another network module.

Some other brands have similar "pass through" or built-in routing.

But the most common architecture approach is to use VLANs, NAT address translation devices, or routers or VPN appliances.

Of those network architecture approaches, the NAT devices probably require the smallest amount of IT/networking experience (and authority inside the company) to use effectively.

 

[Operaghost]

Yes, there is a way to tunnel through. To explain, lets assume the following layout with one chassis with two Ethernet adapters, and another chassis with one adapter:

Your computer: 192.168.1.230

PLC Chassis #1 Enet Slot #1: 192.168.1.20
PLC Chassis #1 Enet Slot #2: 10.10.10.50

PLC Chassis #2 Enet Slot #0: 10.10.10.60

In RSLinx, when you browse your EtherNet/IP driver we will assume you will see Chassis #1, but you cannot see Chassis #2.

If you were to browse to Chassis #1 and view the modules connected to the backplane you would see both Ethernet modules. If you clicked on the "+" next to the module in slot #2 you would see an Ethernet network and if you clicked on the "+" it would not discover the other chassis. But, it can.

You can manually enter in the IP addresses of Chassis #2 Ethernet module. I don't have a live system here that I can walk through, but if you right-click on that Ethernet network and it may be the "Properties" option that gives you the ability to manually enter an IP address (or multiple address).

So by manually entering this information you can now browse and view that other network. Once you browse to Chassis #2 and see the backplane you can right-click on the backplane and create a Shortcut. Give it a name like "Chassis_2" (you can pick a better name) and you will now see that listed as if it were a separate driver just like your EtherNet/IP driver. You won't have to manually tunnel through those modules to get to that remote chassis.

So lets call this tunneling to one level deep. While I have not tried tunneling two levels deep or further, it should be possible.

Note though......this configuration is stored in your copy of RSLinx only. Someone with a different PC will not see this without going through all those settings again manually. I have not tested the RSLinx Backup Tool to see if it saves this configuration. I know at the time I tried it did not save the shortcuts.

The PLC systems also cannot make use of this. You would have to follow Ken's post to get the PLC to be able to do this.

Good luck!


OG