[aphuk]

I have a 1756-ControlLogix L61 PLC on an Ethernet network. There is a Siemens PLC in the field which has data I need to accquire. If I get a drop line to the Siemens PLC and incorporate it into the Ethernet LAN what would be the next step required in order to read data from the Siemens PLC.

The fundamental question is can these PLC's talk to each other directly?

[Ken Roach]

I had one customer claim he was able to create a connection between ControlLogix 1756-EWEB and a Siemens controller using the open TCP sockets feature and writing a custom data exchange protocol.

But that's one guy doing an extraordinary amount of work to prove it could be done.

In general, Rockwell Automation uses EtherNet/IP and Siemens uses Profinet and the two protocols have almost nothing in common.

My approach would be to use a Profibus DP to EtherNet/IP gateway device like the ones built by HMS Fieldbus. There are likely also Profinet <-> EtherNet/IP gateways on the market but I am unfamiliar with them.

[rammin48]

Without knowing which Siemens you have it is difficult to know which protocol. I have had good luck with protocol conversions with these guys http://www.prosoft-technology.com/

[controlsdude]

aphuk, on Mar 17 2009, 08:46 AM, said:

I have a 1756-ControlLogix L61 PLC on an Ethernet network. There is a Siemens PLC in the field which has data I need to accquire. If I get a drop line to the Siemens PLC and incorporate it into the Ethernet LAN what would be the next step required in order to read data from the Siemens PLC.

The fundamental question is can these PLC's talk to each other directly?

Here is a link to a known expert on gateways between plcs. Take your pick. Good tech support and would give you a solution hitting the pavement running. I would not recommend writing it yourself. Probably could waste many engineering hours and get no where. I have used many of there devices and have been satisfied and did not have to struggle to get it to work. And when I could not get it to work, tech support is excellent.

http://www.prosoft-t.../view/full/3253

[Peter Nachtwey]

I would put a Profibus DP card in the AB rack and communicate using Profibus DP.

[kaiser_will]

What is the goal of having the A-B PLC and the Siemens PLC communicate? You say you want to read data from the Siemens PLC. Instead of pulling data directly from the Siemens PLC into the A-B PLC, possibly you might look at a gateway to the pull the data in and make available to the A-B PLC, which is what the ProfibusDP card will do for you.

[JesperMP]

We should put pressure on both Siemens and AB to start supporting OPC UA.

[paulengr]

JesperMP, on Mar 18 2009, 09:39 AM, said:

We should put pressure on both Siemens and AB to start supporting OPC UA.

We should put pressure on OPC to quit creating non-open protocols. Like that's going to happen!

[JesperMP]

paulengr, on Mar 18 2009, 07:55 PM, said:

JesperMP, on Mar 18 2009, 09:39 AM, said:

We should put pressure on both Siemens and AB to start supporting OPC UA.

We should put pressure on OPC to quit creating non-open protocols. Like that's going to happen!

Errr..
Isnt exactly that what OPC UA is all about ?

[jimdi4]

[/quote] Errr..Isnt exactly that what OPC UA is all about ? [/quote]


The existing OPC COM based specifications have served the OPC Community well over the past 10 years, but as technology moves on so must our interoperability standards. Here are the factors that influenced the decision to create a new architecture:

Microsoft has deemphasized COM in favor of cross-platform capable Web Services and SOA (Service Oriented Architecture)
OPC Vendors want a single sent of services to expose the OPC data models (DA, A&E, HDA ...)
OPC Vendors want to implement OPC on non-Microsoft systems, including embedded devices
Other collaborating organizations need a reliable, efficient way to move higher level structured data

The Unified Architecture (OPC-UA) is described in a layered set of specifications broken into Parts. It is purposely described in abstract terms and in later parts married to existing technology on which software can be built. This layering is on purpose and helps isolate changes in OPC-UA from changes in the technology used to implement it. The structure and depth of material to absorb in learning OPC-UA is harder than the OPC COM Specifications. It is best to read the introductory articles and in-depth presentations before tackling the OPC-UA Specifications.

[JesperMP]

jimdi4

It was a rhetorical question. I know what OPC UA is.

Before I sign off this thread for fear of hijacking it too much, I can say that after a little investigation I have found that at least Siemens has begun working with OPC UA. They are far from having an OPC UA stack running on all their PLCs, but at least they have started.
Now we need AB to do the same.

Bye !

[aphuk]

Whoops, looks like I stirred up the comms debate again.

on my requirement.

I currently have a network which has a Multi mode Fibre Optic backbone running thru Hirschmann RS20 switches for each drop. At the moment there are only PC's and Enet Control Logix PLCs connected.

The hope was that I could add another Hirschmann switch in the cubicle where the Siemens PLC resides and then connect it on to the network thus enabling all the other nodes to be able to talk to it.
I am not a LANhead and my simplistic appraoch was that, once the Siemens was physically connected to the network, the Control Logix PLC(s) would see it as just another node. If the Control Logix PLC cannot talk directly to the Siemens then my other thought was that I could use one of the PC's (running WW Intouch) as a 'bridge' by installing a Wonderware I/O server that could talk (over the physical network) to the Siemens PLC and read the registers into its database and then map them into the Control Logix PLC.

any thoughts Gentlemen?

[BobLfoot]

aphuk, on Mar 19 2009, 03:38 PM, said:

my other thought was that I could use one of the PC's (running WW Intouch) as a 'bridge' by installing a Wonderware I/O server that could talk (over the physical network) to the Siemens PLC and read the registers into its database and then map them into the Control Logix PLC.

any thoughts Gentlemen?

The WW Bridge should work well, although the propagation delay might be slow. The bridge devices suggested might prove more useful.

[paulengr]

aphuk, on Mar 19 2009, 03:38 PM, said:

Whoops, looks like I stirred up the comms debate again.

on my requirement.

I currently have a network which has a Multi mode Fibre Optic backbone running thru Hirschmann RS20 switches for each drop. At the moment there are only PC's and Enet Control Logix PLCs connected.

The hope was that I could add another Hirschmann switch in the cubicle where the Siemens PLC resides and then connect it on to the network thus enabling all the other nodes to be able to talk to it.
I am not a LANhead and my simplistic appraoch was that, once the Siemens was physically connected to the network, the Control Logix PLC(s) would see it as just another node. If the Control Logix PLC cannot talk directly to the Siemens then my other thought was that I could use one of the PC's (running WW Intouch) as a 'bridge' by installing a Wonderware I/O server that could talk (over the physical network) to the Siemens PLC and read the registers into its database and then map them into the Control Logix PLC.

any thoughts Gentlemen?

Outside of an ancient Square D PLC (which ran non-IP compatible Ethernet packets), all PLC's that have Ethernet capability can "see each other". But that doesn't mean they talk the same language. Just because you can see someone from Brazil, if you only speak English and they only speak Portugese, it doesn't mean you can communicate effectively.

The lingua franca by the way among PLC's is virtually always Modbus. There are other ways but this is always a solution. You can get virtually every PLC ever produced to speak Modbus somehow, whether natively or with an adapter card of some sort, both as a scanner and a device. From there it's a relatively simple matter to get them to talk.

[TWControls]

You may look at the Red Lion G3 series or a Data Station. It would probably more economical than the Wonderware option and could map the tags Siemens to AB