Free Magazine Subscription
Printer-friendly version
Email to a Friend
EDDL can save numerous man-hours of OPC server configuration and speed up project completion, says Jonas Berge.
OPC is an o p e n standard method for transferring data between software applications, used for example to obtain data from devices. Once an OPC server is configured, external software in HMI clients and other users can easily access the wealth of detailed diagnostics and information in hundreds or thousands of intelligent devicesaround the plant.
Configuring OPC clients is easy: just point and click on data in the OPC server. To enable this, the OPC server must first be configured. Electronic device description language (EDDL) makes this easy.
Configuring the OPC server includes entering device addresses and communication settings as well as creating the “namespace” which entails entering tag or descriptor for each and every piece of information along with the memory register address for the parameter as well as its data type, and range where applicable. This parameter “mapping” is the most time consuming and error prone part of OPC integration, but once done the rest is easy.
Configuration power
For devices using Hart, Foundation fieldbus, or Profibus protocol, the OPC server configuration can be automatic using IEC 61804-3 EDDL standard because the EDDL file for each type of device tells software the name, data type, and location of every piece of information enabling the software to configure the OPC server.
This solution for OPC servers owes much of its ease-of-use to the open standard configuration power of EDDL. This was developed through a cooperative effort between Fieldbus Foundation, Hart Communication Foundation, Profibus Nutzerorganisation (PNO), and OPC Foundation.
EDDL saves numerous man-hours of OPC server configuration and speeds up project completion. Future replacement of devices automatically updates the OPC server as well.
Automatic OPC server configuration is made possible because EDDL is a descriptive technology similar to XML or HTML, declaring the properties of the data in the device for use by the auto-configuration mechanism. EDDL is the only device integration solution that is declarative.
Therefore there are no other means to achieve a comparable result. Moreover, because EDDL in its original form from 1992 is supported by all manufacturers, OPC access is achieved for all devices, old and new, not just a few models.
Jonas Berge is Senior Manager, PlantWeb Consulting, at Emerson Process Management.
