Interfacing LabVIEW with an OPC server through DCOM via the automation

[jfl]

Hello,

I have to develop a LabVIEW application involving a certain number of OPC items (typically one or two hundred items).

From what I read on NI forums and on LAVA.org, I have mainly seen two types of solution : Datasocket or DSC module.

- DataSocket API : it seems that it doesn't suit very well in this case (the number is a bit to high : the creation of one OPC group at each "DataSocket Open" can lead to performance issues).

- DSC : the inconvenient is the price of the license and I think DSC has many functionalities that I don't need for my application (Data Logging, HMI, Database Connectivity...).

I think that an intermediate solution can be to implement the automation wrapper of the OPC foundation. My idea is to use from LabVIEW the DLL "OPCDAAuto.dll" which exposes an Automation COM interface.

From what I understand of LabVIEW, ActiveX and DCOM, there shouldn't be feasibility issues.

I wanted to know if someone had already implemented this kind of solution and what are the capacities in term of performance.

Thank you by advance to anyone able to give me an advice on this topic.

Best regards.

--

jfl

[Tom Eilers]

Within LabView 8.xx you have the shared variable engine, what is an opc server.

[jfl]

Hello Tom Eilers,

Thank you for your message, but I think it doesn't answer to my question. I'll try to be more precise :

Effectively, the shared variable engine included in LabVIEW 8 is an OPC server.

But the application that I want to develop with LabVIEW must communicate (as an OPC client) with an existing remote OPC server which is not LabVIEW.

The topic of my question was to know if someone had already developed, with LabVIEW, an OPC client based on the automation wrapper of the OPC foundation and if the performance are better than with DataSocket API (personally, I think it will be...)

Regards

--

jfl

[David Wisti]

opcware.com has an OPC client toolkit with a Labview example. I've always wanted to create some wrappers around OPCDAAuto.dll with Labview but never seem to have the extra time. Labview can be a OPC client with shared varaibles only with the DSC module. I guess you need DSC to support a tag database.

[Karl Rony]

I went with opcware.com as well. I didn't and still don't have the time to spend weeks tweaking a custom built OPC client solution. With OPCWare, I was productive in under a day.

[jfl]

Hello,

Thank you to dwisti and Karl Rony for your answers.

From your point of view, with this type of solution, are the performance of OPC exchanges far better than with Datasocket API ?

A little question to Karl Rony : on OPCware web site there's a comment on the use of "OPCWare Client Developer" with labVIEW. It has been written by a certain

"- KR, Instrument Engineer & LabVIEW Programmer". Is it a coincidence or is it your comment ?

Regards.

[Karl Rony]

I experimented with LabVIEW's OPC client capabilities with LabVIEW 7.1 using datasockets. My first concern was LabVIEW's recommendation to use the 6.x VIs for OPC client applications. I also had trouble with reliable communications without a 2 second delay between operations.

I wasn't performing the operations very efficiently and pondered the thought of spending a 2+ weeks rewriting and enhancing my code. Instead, I tried out OPCWare and had a nice solution in under 4 hours. I purchased the software that afternoon and never looked back. The OPCWare product has a nice COM runtime interface that allowed me to manipulate the tags in the LabVIEW application as I troubleshooted my development.

One of my LabVIEW / OPCWare application was a small application to open and close a Profibus-DP controlled actuator. A host computer had a Softing Profibus PCI master and the Softing OPC server. I configured tags on the server to support several actuators with a common name structure. By changing the OPCWare XML tag file, I easily ran the same LabVIEW test program independently on several computers controlling separate actuators through the Profibus OPC server.

I am the KR on the web site.

[P. Rosegger]

@KR: Can you give me some additional info on how to use OPCWare with LabVIEW? I'm totally stuck after downloading the demo software. There are no LabVIEW examples to be found :-( Also I don't fully understand the licensing model: If I develop an application on my PC (and therefor install the license on my PC), can I then deploy it on the customer's PC? Does the customer's PC need another license?

I've got the same problem as the thread starter: I have to write 300 to 400 Items and using data sockets it takes between 5 and 10 minutes(!). Any help would be very appreciated.

TiA,

pro

Edit: As this thread is rather old: Does anybody know of any other solution to this problem?

Edit2: I just stumbled across http://www.deltalogic.de/content/view/21/38/lang,en/ - sounds promising...

[Karl Rony]

I'll try and put something together this weekend for you.

One of the licensing options is one developer license and unlimited runtime licenses on any system anywhere in the world.

[Karl Rony]

Here is a demo vi in LabVIEW 8.2.1

[efra_mx]

Here is a demo vi in LabVIEW 8.2.1

I cannot see the VI, could you upload it again please?, thank you.

Efrain