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OPC DataHub Newslink
OPC DataHub -- The only OPC tool you need.
May 2009
Greetings!
Integrating the various pieces of hardware and software in a typical industrial automation system often means thinking outside the box. The OPC DataHub offers new ways to approach problems and complete even the most difficult projects.
- Bob McIlvride, Cogent
In This Issue
Siemens connects OPC and SCADA systems
Featured Partner: Software Toolbox
Are there any limitations for OPC tunnelling?
"Now our clients can open a web browser from wherever they are and see exactly what is going on."
Cameron Burn - PowerData Ltd., Netherlands Antilles
 
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Siemens connects OPC and SCADA systems with the OPC DataHub

In a recent data integration project, Siemens engineers in Copenhagen, Denmark were able to connect equipment and instrumentation running in a high-security facility to a remote monitoring location, using the OPC DataHub.

Image of an OPC tunneling connection between the high-security facility and the monitoring facility.

The goal was to allow technicians access to the machines they needed to work on, without breaching security or permitting any non-authorized personnel on site.

“The OPC DataHub is running very well,” said Carsten, the project leader. “We do a lot of this kind of data integration, and there will be other projects. We have chosen the right solution.”

Featured Partner: Software Toolbox
Software Toolbox logo.

Software Toolbox, Cogent's sales and technical partner for North America, knows that one size cannot fit all when it comes to off-the-shelf automation software. Since 1996 they have provided hundreds of speciality products to thousands of customers--end users, system integrators, OEMs, and large automation suppliers. Software Toolbox is a Charter Member of the OPC Foundation, and is fully involved in product testing to ensure reliable interoperability.

"Cogent's commitment to OPC interoperability and certification is evident in the OPC DataHub, and meets the high standards we set for our diverse client base," said John Weber, President of Software Toolbox. "The OPC DataHub has proven its value time and again in a wide range of industrial automation applications."

Are there any limitations for OPC tunnelling?

OPC tunnelling is an excellent way to network OPC and avoid the hassles of DCOM. You just connect an OPC DataHub to your OPC server, and configure a tunnel to another OPC DataHub on your OPC client machine. But sometimes people ask: are there any limitations on how much data I can send across the tunnel?

Image of OPC tunnelling using the OPC DataHub.

Here are some general considerations:

  • Performance of the OPC DataHub does not depend on the number of points (tags) in the system, but rather on the number of data changes per second that are processed. We have tested the OPC DataHub at 100,000 changes per second in ideal conditions, but a more realistic number would be 20,000 to 30,000 changes per second in the steady state.
  • Although theoretically you are limited only by the amount of memory, systems with over 100,000 or 150,000 tags will experience some slowdowns.
  • The initial connection time can vary depending on the OPC server you are using. Once the connection is made, though, the tunnel will perform at about the same efficiency as a local OPC connection.

With these in mind, here are a couple of suggestions for maximizing performance:

  • If the CPU is overloaded, you can add more processing power. The multi-threaded architecture of the OPC DataHub will benefit from running on up to 4 cores.
  • For large numbers of tags, you can slow down the data update rates for the connection between the OPC server and the OPC DataHub, which will reduce the processing load, as well as reducing network bandwidth.
About Cogent
The OPC DataHub is developed and maintained by Cogent Real-Time Systems. Founded in 1995, Cogent is the leader in real-time cross-platform data integration between Windows, Linux and QNX. Customers include the Bank of Canada, Cadbury Chocolate and the European Space Agency.

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