CompactLogix sending CIP message to a PC

colorofwind · Jul 13, 2012

Hi, we've worked to figure out the CIP protocol for a few days. We intended to write a 2 way communication program using socket between Linux and PLC. However, the AB programming manuals didn't specify all the data that is sent. And the only example of real data (by each byte) is from a PLC to another PLC. We tried to send a packet of bytes (from the example) to the PLC but no response from the other end.

Maybe it's easier to implement only 1 way communication. So is it possible to set the PLC program in RSLogix 5000 and gets it to send the tag values we need to a local IP address (PC) and we'll decode it? How does MSG instruction work in this situation? Or are we even on the right track to tackle this problem?

colorofwind · Jul 13, 2012

This is the TCP/IP structure we tried to implement. Unconnected msg is used.

Screen Shot 2012-07-13 at 11.41.24 AM.jpg

Ken Roach · Jul 13, 2012

Are you trying to read a specific Tag inside the controller, or establish a cyclic I/O connection ?

There are a handful of Linux projects for connecting to ControlLogix; are you using one of them, or starting from scratch ?

colorofwind · Jul 13, 2012

Ken Roach said:
Are you trying to read a specific Tag inside the controller, or establish a cyclic I/O connection ?

There are a handful of Linux projects for connecting to ControlLogix; are you using one of them, or starting from scratch ?

Yes we are trying to read some tag values in the controller, mostly are temperature readings from thermocouple and the valves positions. It's better if we can start from scratch because we only need limited functions, and keep the program size as small as possible to run it on a Linux single board computer. But I'd like to see some linux projects and I'm sure it will be helpful to us.

Ken Roach · Jul 13, 2012

My first few pointers would be:

http://sourceforge.net/projects/opener/

http://freecode.com/projects/cell

colorofwind · Jul 13, 2012

Ken Roach said:
My first few pointers would be:

http://sourceforge.net/projects/opener/

http://freecode.com/projects/cell

Thanks, Ken! We tried a older version of the second one. It seems can establish the communication with our CompactLogix PLC. However, when we use the demo program to read tag values, it can't get anything. I don't know where we did wrong.

Ken Roach · Jul 13, 2012

My next step would be to get Wireshark traces of your application attempting to read the controller and compare them to traces of a known-working application (like RSLinx Classic) reading the controller.

nettogrisen · Jul 16, 2012

I was able to exchange data between a CompactLogix and my linux box using the CIP/EthernetIP specs, the logix5000 data access manual and Wireshark.

That should be all that you need.

dmroeder · Jul 16, 2012

nettogrisen said:
I was able to exchange data between a CompactLogix and my linux box using the CIP/EthernetIP specs, the logix5000 data access manual and Wireshark.

That should be all that you need.

You wrote your own code to do this?

colorofwind · Jul 16, 2012

nettogrisen said:
I was able to exchange data between a CompactLogix and my linux box using the CIP/EthernetIP specs, the logix5000 data access manual and Wireshark.

That should be all that you need.

Hi there, instead of Wireshark, we used another TCP/IP sniffer to track the packets sent and received. But still we encountered two problems.
1. The CIP/EthernetIP spec sheet didn't tell us the meaning of all bits that are sent to the PLC. Some definitions are very vague.
2. When we used an old version of CELL that was mentioned above, it can talk to PLC. But the process of exchanging information, or to shake hands with PLC, is different from what we read in the spec document. Although we can't successfully retrieve any tag value by using this program, the sniffer showed that it did communicate successfully with PLC.

s.jeanne · Jul 17, 2012

Have a look at : http://code.google.com/p/tuxeip/
you Will find a library, some explanations and sample applications that can do the job

colorofwind · Jul 17, 2012

s.jeanne said:
Have a look at : http://code.google.com/p/tuxeip/
you Will find a library, some explanations and sample applications that can do the job

Thanks a lot! From the webpage, it has nothing to download?

Anyway, I'll google for it.
Edit: Just found the command-line access for it!

colorofwind · Jul 17, 2012

s.jeanne said:
Have a look at : http://code.google.com/p/tuxeip/
you Will find a library, some explanations and sample applications that can do the job

Wow, Stéphane, I didn't realize you're the author of this program. Very cool!!!

s.jeanne · Jul 18, 2012

I hope it Will help you,
let we know

nettogrisen · Jul 18, 2012

dmroeder said:
You wrote your own code to do this?

Yeah. I havn't had the time to finish it though. My plan was to have it log data into an SQL database on my NAS.
Some day...

colorofwind said:
Hi there, instead of Wireshark, we used another TCP/IP sniffer to track the packets sent and received. But still we encountered two problems.
1. The CIP/EthernetIP spec sheet didn't tell us the meaning of all bits that are sent to the PLC. Some definitions are very vague.
2. When we used an old version of CELL that was mentioned above, it can talk to PLC. But the process of exchanging information, or to shake hands with PLC, is different from what we read in the spec document. Although we can't successfully retrieve any tag value by using this program, the sniffer showed that it did communicate successfully with PLC.

Does your sniffer know Ethernet/IP and CIP? Wireshark does, and it breaks it down for you.
1. Can you post which parts you are having trouble with?
2. I havn't tried CELL but maybe it's using connected messaging. That's what I did.

I would of recommended tuxeip, but i see that Stéphane already did.

CompactLogix sending CIP message to a PC

colorofwind

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Ken Roach

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