S7 & Controllogix over Ethernet

beethoven_ii

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I'm working in the planning stages of a big project which will require data exchange over Ethernet between 8 off S7 plc's and 6 off Controllogix plc's. I've spoken to our normal hardware supplier tech support guy and he has advised me to use an Anybus gateway (www.anybus.com) to translate the different Bradley & Siemens Ethernet protocols.

I have done Ethernet communications before between Bradley plc's, S7 plc's and between S5 & S7 a while ago, but never between Bradley & an S7. The Bradley plc's are our responsibility and the S7's are from another equipment supplier on the same project.

We need to exchange a DINT in either direction between each Bradley plc and each S7 plc. I want to use the MSG instruction on the Bradley side of things and wondered in the naming of the DINT tag in my Bradley plc was important to make it easier to set things up from the S7 side? I'm assuming at this stage that the S7's will be using the AG SEND and AG RECEIVE functions and seem to recall that the TSAP settings had to be identical on both plc's for everything to work when using Ethernet comms with Siemens. Obviously I have no TSAP settings on my Bradley plc's.

Does anyone in here have any experience of setting up communications over Ethernet between an S7 and a Controllogix plc?

Any help or pointers would be greatly appreciated. I realise I've waffled on a bit but hopefully someone will get the drift of what I'm asking.

...Ludwig
 
We did it with profibus a few years ago. passed single integers only. But what I remember about the whole thig was--when the integer lower and upper bytes were transposed. We had to swap the bytes at one end or the other. I don't think the comms did it--I think it's just the way the processors look at them. I wonder what the DINT's will look like.
 
Yes, the only direct way of transmitting data between S7 and AB Logix PLCs is via Profibus, one has to be master and the other slave. Siemens mention MySST's Profibus modules on their website, so this is a nod of approval.

You can also go indirectly via ethernet and a protocol converter. This does not involve a PC as an intermediary go-between. INAT has a protocol converter for ethernet that Siemens mention. Probably the anybus device is OK to use as well.

There are also esoteric methods of using a CP in the S7 that speaks AB DF1, or a module in the logix that speaks Siemens 3964R. But I would only consider this if none of the other methods can be used.
 
This is possibly because Siemens work in bytes and just about everyone else works in words.

I also find I regularly have to swap bytes and words on Device Net and Modbus RTU. Not uncommon.
 
BobB said:
This is possibly because Siemens work in bytes and just about everyone else works in words.
No, it has something to do with "little endian" and "big endian".
I am sure that all the bytes in the DINT are mingled together. Easier to experiment to figure out than reading the manuals.
 
No, it has something to do with "little endian" and "big endian".

It is absolutely great when you get a device where you can swap little and big endian and saves you a lot of work. I have only ever found one and that is an Ozzy generator controller. Bloody marvellous!!! Saves me hours of work.

Easier to experiment to figure out than reading the manuals.Today 10:51 PM

Very much so if you know what you are looking for. Voltage, for example, is easy.
 
I initially proposed Profibus using a Prosoft MVI56-PDPS in our Controllogix rack as an alternative to Ethernet but the other supplier came back and said they don't want to use Profibus because it "would create major problems according to our PLC layout with redundant array of Master-PLCs."

Ethernet is the preferred method of communications and I now need to find out how we do it.

...Ludwig
 
JRW said:
I've come across this unit before whilst researching my options but found the following limitation a bit restrictive:

"The usefulness is limited by the restriction to "integer" as the only data type which the concerned controls are allowed to exchange."

Also by using the Anybus system I only need one gateway device to allow the full matrix of communications between all 14 plc's. Not sure if that is the case with the Echochange unit.

I've just downloaded the manual which I'm trawling through, and there appear to be some very useful guides in there which will hopefully help me with my set up even if I use the Anybus system.

Thanks for the pointer.

...Ludwig
 
beethoven_ii said:
I'm working in the planning stages of a big project which will require data exchange over Ethernet between 8 off S7 plc's and 6 off Controllogix plc's. I've spoken to our normal hardware supplier tech support guy and he has advised me to use an Anybus gateway (www.anybus.com) to translate the different Bradley & Siemens Ethernet protocols.

I have done Ethernet communications before between Bradley plc's, S7 plc's and between S5 & S7 a while ago, but never between Bradley & an S7. The Bradley plc's are our responsibility and the S7's are from another equipment supplier on the same project.

We need to exchange a DINT in either direction between each Bradley plc and each S7 plc. I want to use the MSG instruction on the Bradley side of things and wondered in the naming of the DINT tag in my Bradley plc was important to make it easier to set things up from the S7 side? I'm assuming at this stage that the S7's will be using the AG SEND and AG RECEIVE functions and seem to recall that the TSAP settings had to be identical on both plc's for everything to work when using Ethernet comms with Siemens. Obviously I have no TSAP settings on my Bradley plc's.

Does anyone in here have any experience of setting up communications over Ethernet between an S7 and a Controllogix plc?

Any help or pointers would be greatly appreciated. I realise I've waffled on a bit but hopefully someone will get the drift of what I'm asking.

...Ludwig

Imagine a telephone with a German speaking on one end and a North American speaking English on the other end. The fact they both have compatible phones (ethernet) does not mean they can understand each other(protocol)

Profibus is the way to go with the SST profibus card, that way the two PLCs are both talking German over the telegraph lines


Ian
 
If we were in the communication business.....

If the devices are truely Profibus compatible then data is exchanged without having to swap bytes. This is one of my big pet peeves.

I would use Ethernet to communicate between all the PLCs. This may takes some knowledge and effort to write the software that can translate between the two protocols.

What may seem odd is that we can translate between the two protocols over ethernet easily but we aren't in that business. We leave this to the Red Lion and SST guys but they probably would have said something by now.
 
Siemens to Rockwell

Hi New here so go easy on me..

This is an option I'd look at:-

I believe both these products support UDP but check, (u may need to consider purchasing or upgrading communications processors)
Then its possible to send data via UDP.
http://en.wikipedia.org/wiki/User_Datagram_Protocol

I've written quite a bit on Siemens CP cards for sending packets from and too allsorts of systems and generally find UDP a nice way to do things from SCL you can also implement it using STL or Ladder to form your packet then use the LGSEND function (I think from memory).

I have to say Profibus would take away the need to do any real programming though so would be inclined to look into that.

A third suggestion is to put a Ruggerised PC in $700? say from Advantech? and run a SCADA on it that talks to both eg wonderware do a $750 64 Tag product that ships with one I/O server you'd have to purchase another then just map the tags across. That would be very simple and relatively cheaper than adding Profibus to quantity of PLC's but again a cost for not having to do any real programming. You may also have a PC on the network that you could utilise? how critical is it? Profibus would win over if its critical etc

Anyone know of any automation work in Sydney?

David Askew
www.fast-automation.com
 
Since this thread was started, I have heard that direct data exchange with ethernet sockets is possible. The ControlLogix module must be an EWEB, not an ENBT. Do a bit of searching and you can find a couple of people who have succeded with it.
 

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