Ethernet IP Questions

Nitay

Member
Join Date
Dec 2011
Location
Israel
Posts
14
Hello,

I'm implementing an application to connect to Rockwell Automation PLCs using Ethernet/IP, and I ran into some difficulties:

1. The specifications aren't free. Although it says so on every document I found on ENIP. Does anyone know a good source to learn about the protocol? I have some documents I found with google, and I understand the basic structure, but I need some info about the different Address Items & Data Items, which I don't fully understand yet.

2. What's the difference between connected and unconnected messages?

3. What's this connection-id field you have on the connected messages? What does it represent? It's not the same on the command & on the telemetry.

Help with these subjects will be greatly appreciated...

Thanks
Nitay
 
I've been through this with a few companies who refused to pay the ODVA membership fee on principle and instead burned through several months of programming labor and badly damaged their technical and commercial relationship with Rockwell Automation.

It was unpleasant on the technical side and very unpleasant on the commercial side.

Join the ODVA, get the specification, and do the Conformance Test.

There are arguments, sure, but in my experience there are no good commercial justifications for not joining the ODVA and doing this right.
 
Upon reflection, my first reply was one of those unhelpful "don't do that" replies. I have good reasons for my opinion, but that doesn't make it helpful.

One resource you might want to look at is from Rockwell Automation and explains the addressing of Tags in the ControlLogix environment. It's called the Logix 5000 Data Access Manual.

http://www.rockwellautomation.com/enabled/guides.html

The basic CIP Connection methods and allocation of Connection ID's and the function of the Unconnected Message Manager is the sort of thing you need the ODVA Specification for.
 
I'm trying to convince my superiors to join ODVA - It will probably take a while though.

I think this document will suffice at least for starting implementation!

Thanks a lot for your help Ken!

Nitay
 

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