Messaging Between Control Logix and Siemens S7

SFBanks

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Jul 2007
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Hi,

I am currently replacing 2 Siemens Series 7 PLC's with a Control Logix PLC. There is also a 3rd Seimens S7 PLC onsite that is not being replaced at the moment.

At Present there is a few peices of data that are being transfered between the S7 PLC's.

What I am wanting to know is there anyway to send any data to and from S7 and ControlLogix? They could be connected via Etrhernet. I was thinking possibly a generic Message instruction?

Any Help Appreciated
 
I know only this:
You can program lowlevel socket communication with the EWEB module.
And with S7 you can also program "open" communication functions with Ethernet.
So I am almost 100% certain that it is possible. But to actually accomplish it is another matter.

This is one of these cases where it would be great if someone went and did it, and then wrote a nice little guide for the rest of us.

I dont have controllogix at hand, and I also have way too little experience with controllogix, so I cannot do it.
 
Thanks for the reply.


I am in the opposite boat. I have a lot of experience with ControlLogix and very little with Siemens.

Together we may be able to do it! :)
 
I am familiar with the Controllogix EWEB and it's socket interface. I have an EWEB module I could test on. Unfortunately I'm in the same boat as Jesper. I don't have the Siemens hardware and Jesper would probably have to walk me through going online with the processor
 
I formed a team of folks last year that tested and demonstrate CLogix and S7 comms three different ways to see which way worked best. Two of the ways untilized Ethernet and one way PROFIBUS.

Ethernet
1) Using a CLogix with a EWEB module we configurated (with much help from RA and a customer) native socket comms with a S7-315 PN/DP and passed a few hundred bytes of data between the two. It took sometime to make this work. Pros: it worked and worked rather well Cons: EWEB module cost, ENBT had to be used in addition to EWEB because of Ethernet/IP IO was needed too, and the biggest draw back was the amount of code, configuration and complexity of the comms between the two.

2) Using a PROFINET proxy from Woodhead http://213.130.34.122/pdf/en/applicom_PROFINETIO%20Proxy.pdf we setup a configuration for both Ethernet/IP and PROFINET and passed a few hundred bytes between the two. Pros: easy to setup, cost was better than expected, performance was pretty good. Cons: another device, another configuration, another point of possible failure

PROFIBUS
3) Using a Woodhead PROFIBUS module http://213.130.34.122/pdf/en/SST_PFB-CLX-RLL_FDT.pdf in the CLogix rack we setup a few hundred bytes of data between the CLogix and S7 using PROFIBUS. Pros: best performance, easy configuration, lowest cost option, clean layout. Cons: another network link, but our application allowed for only a meter of PROFIBUS cable to be used between the two controllers so it was not that big of a deal.

The final decision was made to use the PROFIBUS configuration because it was the lowest cost, best performance, easiest to setup and maintain.

Key points, the native socket comms on the RA side required EWEB module which didn't support EIP IO traffic so another ENBT was needed too. Both the S7300 and 400 family of PROFINET CPUs supported native socket comms and all of the CP343 and CP443 support native socket comms. If using the Woodhead PROFINET proxy required that you used a PROFINET enabled CPU or a CP343 / CP443 PROFINET supported CPU.

Another option if you rather have a software solution. Use a PC with OPC DX servers for both CLogix (EIP), and S7 (Ethernet S7 Communications, or PROFINET). OPC DX (Data Exchange) allows bridging between two OPC server so the PC becomes your traffic cop (bridge). I've not done or seen this done with CLogix / S7 comms, but have seen this done with TI / S7, and Modicon MB+ / S7 and it worked rather well.

For your application with (2) CLogix and (1) S7 I would look at either the proxy or PROFIBUS in the CLogix racks. It took a great deal of code and hand shaking between (1) CLogix and (1) S7 in my test to make this work.

Good luck on your path forward.
 
Last edited:
Hi mday.

You are right, an EWEB is a bit out of the ordinary. So in almost any case this solution will mean additional costs.

Still, I sometime hear the need for a direct connection between S7 and CLX and it could be fine to add this possibility to the arsenal.
About the complexity, I guess one could pack the lot inside a library.

So can we pursuade you to describe the details a bit more - both on the S7 side and the CLX side ?
 
JesperMP,

I'm on vacation and don't have access to my files. I will see what I can provide when I get back to work.
 
mday said:
Another option if you rather have a software solution. .... OPC DX (Data Exchange) allows bridging between two OPC server so the PC becomes your traffic cop (bridge). I've not done or seen this done with CLogix / S7 comms, but have seen this done with TI / S7....

I am currently working at a client's site where they extensively use an OPC servers to communicate between S7 and Ti PLC's. The system works reasonably well BUT (there's always a but) I feel the biggest drawback is the nagging doubt that the cleaner may just accidentally unplug the PC running the OPC server and secondly the OPC server will most likely be running on a Microsoft OS and although they are becoming more reliable they are still not as stable a platform as a PLC.
 
Since you may have to buy extra cards etc. it may be easier and cheaper in the long run to change the 3rd S7 to AB, possibly using Compactlogix for a lower cost and ability to program with RSL5000.

Just a thought, I know it depends on situation.
 

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