PLCs and OPC

[jtn]

Give this a look.

http://www.prosoft-technology.com/content/view/full/10951

Maybe that is what you are looking for?

 

[surferb]

Dan,
I read the website details to indicate a model that is pretty much just like everyone elses with respect to OPs requirement. The first statement in their paragraph is saying that their OPC server can communicate with their PLCs. That's what OPC servers do. Based the diagram on that web site and the description, it's clear that the OPC server is not embedded in the PLC. I would estimate it nearly impossible to implent a DCOM based OPC DA 2.0 spec OPC server given most PLCs architecture and computational power (sure a SoftPLC, read PC, could do it fine). Given the technology this just doesn't make sense.

I sat through some Codesys overview training last week.

The statement was made that Codesys has an OPC server embedded in it, so those hardware targets that run a Codesys compiled binary have an OPC server as part of the configuration. The Codesys web site confirms that
http://www.3s-software.com/index.shtml?en_OPC&sitesearchmatch=opc#sitesearchmatch

Note the claim:
The CoDeSys OPC-Server V2.0 is able to communicate with all controllers programmed with CoDeSys. It complies with the requirements of the OPC standard V2.0.

I pressed the issue by asking whether or not an OPC server was a licensed run time extra, and the claim was that it is not.

I think Beckhoff uses Codesys as its development platform/runtime software, does it not? If so, it might place in this category.

If the Codesys statement is true, then the spec could be a lock-out spec.

Dan

 

[SteinCollector]

Thanks for all the feedback - I was traveling for a couple of days, so this is my first time checking back. I will investigate the Codesys trail. I do not have any experience with Beckhoff, but I have used the Bosch-Rexroth PLC, which is also Codesys based. I don't recall learning anything about an embedded OPC server, but it's worth checking out.

 

[SteinCollector]

How it turned out

Turns out this is all a big mistake made by the Chrysler account manager. There is no embedded OPC spec - only a 2 ethernet port requirement. This opens quite a few options for me, now! Probably going to go with a Mitsubishi Q or maybe the Rexroth L65.

Thanks for all the feedback!

 

[Flopro]

This Spec exists-

The OPC DX spec is over 5 years old but I have yet to see it avaliable in all the PLC vendors processors. It is a PLC to PLC OPC standard. Can you imagine being able to share values between MODICON, DeltaV and a ControlLogix without anything other than an Ethernet connection? No protocol converters or translation required! I'm still waiting...

 

[JesperMP]

Flopro, you must confuse OPC DX for OPC UA.

OPC DX does not allow direct PLC-to-PLC data exchange without a Windows PC as a go-between.
OPC DX allows data exchange between OPC Servers (on a Windows PC) without an OPC Client as a go-between.

 

[Flopro]

I Might Be Wrong-But, Maybe Not!

What is OPC DX ?

The OPC Foundation designed the OPC Data eXchange or OPC DX standard to address the needs of device-to-device or bus-to-bus communications without having to go up into the HMI or other higher layers.


Maybe I'm missing something?

 

[JesperMP]

Flopro. Why the large font ?

Read this "mission statement" from the OPC Foundation refarding OPC DX:
http://www.opcfoundation.org/Default.aspx/04_tech/04_spec_dex.asp?MID=AboutOPC

Notice that it says "To provide an industry standard for exchanging data between OPC Data Access servers. The solution will avoid the overhead associated with inserting a proprietary client between the two servers. "
Like I said. OPC Server-to-OPC Server data exchange. This to avoid using an OPC Client.

Just to clarify it exactly. OPC DA Servers are until now solely defined to be a piece of software on a Windows PC that interfaces to external devices via COM/DCOM.
I could link to examples of OPC DA servers that support DX - but I cant be bothered to. I suggest you link to an OPC DX that can be installed directly on a non-windows device

 

[Flopro]

Sorry Dude...

Okay JesperMP,

Just so your feathers don't get too ruffled; I copied and pasted the definition so the font size came from the clipboard...

Your link states:[font=Verdana, Arial, Helvetica, sans-serif]To define server-to-server and device-to-device communication across Ethernet Fieldbus networks.


It really doesn't matter, but 5 years ago when the PLC manufacturers started talking about OPC DX in their processors and Emerson, Rockwell and Schneider Electric all began demonstrating their products at shows, I took note. Today, however, the feature isn't available. So our discussion is a moot point.

Sorry for your misinterpretation of my tone.

Good day.

[/font]

 

[JesperMP]

OK, dont worry.

It does indeed say that sentence about device-to-device. To me it looks like someone thought it would be nice to have too, not realising that it would open up a completely new branch of technological development.

I actually went and searched for all OPC DX servers on the OPC Foundation site.
There were approx 7, all of them requires a PC with some kind of Windows OS. I think that DX is dead, whereas UA may have some potential for success.

 

[deva]

It is indeed not clear at all, but I interpret it as that the OPC UA Server connects to the Beckhoff PLC and Serves the data from there to other devices.
The OPC UA Server comes in two versions for Windows and Windows CE, and I think they are intended to be installed on the same Windows or Windows CE device where TwinCat resides.
It was released just recently, so there is not so much information about it, no manual for example.

Hi Jesper ,
Can you help me how to connect twin cat plc and twincat opc ua server . If possible can you please provide any documentation for this .Thanks in adavance .

 

[JesperMP]

I have no experience with Beckhoff.
But here is a link to a page with links to Beckhoff OPC UA:
http://infosys.beckhoff.com/content/1033/tcopcuaserver/html/tcopcuasvrce_generalconfig.htm?id=22710