Micrologix message passing (over ethernet)

Does anyone know if it is possible to message directly between two Micrologix 1000 PLCs. (To share integer data)??

Each micrologix has a NET-ENI module hooking it to an ethernet network.

I am having a tough time finding information on the feasbility of doing this.

I believe it would be possible to share the information via a PC that talks to all of the processors, but I really need to message directly between processors.

There is a MSG instruction, but that seems to be geared toward DH485 (or similar) type networks.

You're catching on; the MicroLogix 1000 controllers only support DF1 and DH-485 protocols. When you configure a message instruction in the MicroLogix, the only destination addresses you can put in are DF1 or DH485 Node addresses, not IP addresses.

That's where the Net-ENI comes in; it translates DF1 over a serial line to DF1 encapsulated in EtherNet/IP.

The Net-ENI has a table inside it with fifty DF1 Node / IP Address equivalents. When you send a message to Node 5, for example, the Net-ENI looks up what IP address is mapped to Node 5 and sends the message there.

This is pretty well explained in Chapter 5 of the User Manual.

Read also about the limitations of the Net-ENI. It works pretty well for networking one or two controllers together, but it has a limited number of TCP connections (6 total) and can run out of steam fast.

Ken,

We have a SLC 5/05 and a Micrologix 1200 with a NET-ENI which is connected to our office network. When I was on the road recently I was able to VPN to our network and see the 5/05 but the 1200 had a red X through it in RS Linx. I didn't really try to troubleshoot it at the time. I would think I should be able to see both devices shouldn't I?

Also are you familiar with the functionality of the AB ethernet modem? If I dial into it shouldn't I be able to see any device on the network?

The ENI needs to know the IP addresses of ALL the stations on the network that it is going to need to respond to.

The key is that the 1200 does not know about your VPN, it only knows DF1/DH-485 addresses, so when it gets an RSLinx browse request, it is the ENI that puts a "TCP/IP wrapper" around the 1200's DF1 packet response.

It is my guess then that the VPN connection does not appear on the network as the same IP address as the regular PC...mmm, my IP networking skills are running out of puff about here. Maybe Ken would care to confirm this.

I had a network of 4 ML 1500's all over ethernet to a wonderware system. The machines where timed in pairs as well. One thing, no online edits with the ML line. And the net-eni' - ML connection only runs at the slower com speeds as well. So, it can be done, with some complexity even, but its so much easier to use a processor with native ethernet. But since they are 1000's, how complex can it be.

Matt