OPC-SMS: a wireless gateway to OPC-based data sources

7 This paper describes OPC-SMS gateway, a platform that integrates IP networks with the Short Message Service (SMS), in 8 order to deliver an integrated service for access to data sources conforming to Object Linking and Embedding for Process 9 Control (OPC) standard specifications, through SMS-enabled mobile devices. The gateway supports pull and push services in 10 order to support both request-based and alarm/scheduled-based notifications, respectively. The proposed architecture is based 11 entirely on the ubiquitous HyperText Transport Protocol (HTTP), Simple Object Access Protocol (SOAP), Extensible Markup 12 Language (XML) protocols, and the Global System for Mobile communication (GSM) network and thus exploits the network 13 infrastructure already in place. The capability of accessing different types of OPC data sources (real-time and historical) by any 14 SMS-enabled device consists of a highly flexible service, supporting mobility and event-based notification. A pilot 15 implementation of our approach has been tested in a large-scale installation for accessing OPC data sources of several 16 automation subsystems in a hospital. 178 D 2002 Published by Elsevier Science B.V. 19 20