| The traditional remote maintenance for process control system has many problems, such as having a network delay, being not able to share maintenance technology and having a high maintenance cost. These problems restrict the development of remote maintenance for process control system. With the popularity of Internet network and the maturity of SOA architecture, the application of SOA architecture in the remote maintenance for process control systems has been gradually shifting from theory to reality. This paper presents a new architecture of remote maintenance for process control system based on SOA which combines Web Services and DDS. This new architecture not only greatly improves the efficiency of maintenance, and makes maintenance services have reusability, but also greatly reduces the system maintenance cost, thus significantly increases the economic benefits of enterprise.The new architecture of real-time remote maintenance for process control system based on SOA which combines Web Services and DDS can play the advantages of each. The maintenance of new architecture solves the problems of traditional maintenance effectively. Web Services can package all kinds of application program easily and make maintenance have repeatability. The DDS has a highly efficient data transmission capacity, which can reduce network delay, guarantee the real-time need of remote maintenance.The step of remote maintenance is constituted by communicating through DDS and implementing remote maintenance operations. First on site operators transfer the calculated data to the remote maintenance terminal through DDS updating the simulation model of controlled object, then remote maintenance persons implement specific maintenance operations base on SOA. Four remote maintenance operations based on SOA are introduced: the remote updating of controller, remote video monitor the control site, sending an email when control system failure appears, the remote updating of compensator parameters, the communication between on site and remote maintenance terminal is designed, and the development and design of publishing and remote calling maintenance services in remote maintenance is completed.Finally, remote maintenance for process control systems in A3000 devices based on SOA is implemented. At first, an OPC client is set up, afterwards a predictive control system for the under water tank is built, then the method by which does Matlab call a user-defined Java method is explained. The under water tank model is calculated by field data, the simulation model of the under water tank on remote maintenance terminal is given by the calculated model, afterwards on site operators transfer the calculated data to the remote maintenance terminal through DDS updating the simulation model of under water tank, at last the remote maintenance operations based on SOA which combines Web Services and DDS are implemented, such as updating the on site predictive control system, updating and maintaining the on site process control algorithm and remote video monitoring the A3000 system. The experiments indicate that the architecture of remote maintenance for process control system based on SOA which combines Web Services and DDS could greatly increase the efficiency of maintenance, guarantee the real-time communication, and reduce the maintenance cost. |
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