Automation engineers Franck Fontanili and Thomas van Oudenhove at Ecole des Mines d'Albi-Carmaux (EMAC) in France recently implemented the OPC DataHub to a connect PLCs at a remote production line to the Witness simulation server in their offices. Both systems are securely protected by firewalls. The resulting OPC tunnel connection is fast, reliable and secure.

Mr. Fontanili has recently returned from attending the 17th IFAC World Congress in Seoul, South Korea. His presentation of this experimental platform in a session concerning Remote Laboratories received an enthusiastic response. "We are very pleased with the system performance," he said. "For our remote access to work, we needed a secure and reliable connection across the network to our OPC server. The OPC DataHub was exactly the right tool for the job."

AJAX technology has been around for a few years and is fast becoming the platform on which the next generation of Internet applications will be delivered. AJAX uses Javascript code embedded in the page, which is interpreted by the web browser. The Javascript code periodically sends commands to update the data on the page. The data updates automatically, without the need to refresh the page. This is also called "client-side scripting".

With the DataHub Web Server you can easily create dynamic web pages using AJAX that can be viewed on any browser, including web-enabled phones and hand-held devices. The DataHub supports both traditional Polling AJAX displays as well as new Streaming AJAX displays that significantly reduce the load on the server when dealing with larger numbers of display points and higher speed update rates.

A company in Europe is using the OPC DataHub Scripting capability to collect data from an OPC server and store it as a comma separated value (csv) file. The DataHub script was developed to simply write a new line to the file every time a set of point values changed in the OPC server.

The script also does some conditioning on the data before it is written to file, so that alarm event numbers are converted into plain text strings to make it easier to analyze later.