OPC and XML in Building Automation

LOYTEC, an Austrian manufacturer of building automation products, embeds the OPC XML/DA standard into one of its building automation products

In 2003, an open letter to the Building Controls Industry proposed to establish a consortium that would work on the creation of a guideline for use of XML and Web Services in building automation and control applications. The first paragraph of the open letter reads:

"The Building Controls industry has made great strides over the last 10 years in the creation of communications standards. Both BACnet and LonTalk are now viable, commercially accepted solutions that provide owners with open communications. Yet while we have made great progress in these areas as an industry, there has been an emergence of a larger, more globally accepted standard created by the world of Information Technology. In particular the broad acceptance and ever lowering cost of Ethernet / TCP/IP / XML communications is finding its way into our industry.” [read full letter…]

In building automation today, it is frequently necessary to provide access to data points in a building via conventional Web-based methods. This may be required for operating controls in Web browsers, for connections to standard software packages for visualization, or for facility management. Direct access from ERP (Enterprise Resource Planning) systems to building data is becoming increasingly important as well. OPC XML-DA provides for a standardized, vendor-neutral Web service which can also be used in building automation.

Conventional DCOM solutions are usually based on a central OPC server. The disadvantage of this is that it calls for a dedicated Windows PC and represents a single point of failure.

The L-OPC from LOYTEC, an Austrian manufacturer of building automation products, is one of the first embedded OPC Server according to the OPC XML/DA standard. The L-OPC implements access to a user defined set of data objects through the use of Web services according to the OPC XML/DA standard. No dedicated PC is necessary. By using Web services, the data access is very firewall friendly and the L-OPC seamlessly integrates into systems connected via the Intranet/Internet. In addition the L-OPC can serve customized Web pages to display network data. With JavaScript or Java applets the L-OPC can also display active content on its Web pages

By mapping native data points to Web services, several L-OPCs can be combined to form a type of distributed Web service gateway. The L-OPC also distributes OPC network traffic to the respective local segments. The porting of Softing's C++ XML-DA Toolkit from the Windows platform to the embedded OS platform was easily accomplished due to Softing's strict adherence to the ANSI C++ standard while writing source code. In the device, native data points are exported from EIA-709 (Lon® networks) or BACnet to OPC-tags. LOYTEC selected Softing’s OPC C++ XML-DA Toolkit for implementing a its OPC Server because it enables the Design Team to concentrate on the project goal and not on learning the intricacies of DCOM, SOAP, or other underlying Microsoft technologies.

Integration with standard OPC DA Client applications (e.g. SCADA systems) is easily performed with Softing’s OPC Easy Connect Suite, a comprehensive set of OPC middleware products designed to simplify the configuration and to optimize the operation of OPC Client and Server systems. Softing’s OPC Bridge, one component of the Easy Connect Suite, serves as an “OPC gateway” used to seamlessly bridge between OPC Specifications; e.g. between OPC DA and OPC XML-DA or between OPC DA V1.0 and OPC DA V3.0. In addition, the OPC Bridge has been used to achieve full OPC compliance for outdated OPC Servers; e.g. OPC Servers that adhere only to the OPC DA V1.0 specification.

The embedded OPC server of the L-OPC is able to manage up to 1000 OPC tags per device and is ideally suited for the following applications:

  • Interface for visualizations and SCADA systems
  • Web visualization of individual areas
  • Room control via a Web browser
    In addition to the OPC XML-DA technology the LOYTEC L-OPC supports data recording, monitoring of alarm states, and scheduling of daily routines.

    Dr. Stefan Soucek, LOYTEC summarizes LOYTEC’s experiences during the development: "We reviewed several options for developing an embedded OPC server. Softing's XML-DA Toolkit proved to be very easy and quickly portable. The quality of the OPC software and the support confirmed that our decision to opt for Softing as our partner was perfect."

    The OPC standard as a widely accepted industry standard for visualization applications ensures a high level of interoperability.

    Softing, a member of the European Steering Committee of the OPC Foundation and author of the OPC Book, actively contributes to the success of OPC by providing high quality OPC products that enable our customers to stay in the lead.

    For more information on how Softing can assist you please click here