Connecting PLCs with the same IP address

Hi all,

Ignition 8.04, Windows 10
KEPWARE Server 6.8
Task: to connect 6 PLC ELAU C400 that have the same IP address (and it cannot be changed).
Connecting one PLC to the PC has no issues. What needs to be done in case when multiple devices with the same IP address must be connected? Someone to share experience?

Each machine will need some network gear in front of it doing NAT or something like that. You can’t have multiple instances of the same IP on a network.


Yes, this is what I know too, I was wondering if someone has done something similar already, so at least some recommendations from hardware point of view could be shared.

Ah, okay. I will defer to those who’ve actually put things into production for a hardware recommendation.

Like @Kevin.Herron indicated, the use of a NAT device will be required. Rockwell has quite a few options for NAT stuff with their Stratix line of hardware.

Does the facility already have network connections to these devices? If so, there must already be some form of NAT in place (independent VLANs). I would look for that information and piggy-back on that. If not, I would strongly recommend having this done in a managed switch with layer3 support, if not in an actual firewall.

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Couldn’t recommend this bad-boy enough (500$):

Might be helpful:

I plan on updating this post. With a guide of sorts.

With what I, as a very novice network/IT eng, did when I was in your situation.

But, basically you need to set up a network device to isolate ports from each other. And NAT 1:1 translate packets between devices and server.

Or you could use a device for every machine. Like with what was mentioned above. With Stratix switches or something. If $$$ isn’t an issue. I’d go that way.

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What about using the MikroTik map. I use these for wireless PLC access points. Approx 30$ each.

Not sure if it would work but you could assign each one a unique ip on your network, plug it into your plc and do some port forwarding. This way you use the map ip rather then the plc ip.