Transparent interaction of SCADA systems developed over different technologies

Supervisory control and data acquisition (SCADA) systems are usually distributed applications designed and developed by using a middleware technology. In this paper, it is proposed a solution for interoperability of SCADA systems that are based on different middleware technologies. The proposed solution allows the interconnection of SCADA system based on the following middleware technologies: OPC DA, OPC .NET, OPC UA, TAO (The ACE ORB - an open-source implementation of CORBA standard), and OpenDDS (an open-source implementation of the DDS protocol). The proposed solution is a software application that allows the creation of middleware objects in order to connect to the data servers. In the application framework, it is allowed the interconnection of the tags exposed by the middleware objects (tags are acquired from data servers through a middleware) directly or by a math expression. The proposed solution is scalable in the sense that it can be added new software modules for other types of middleware in addition to those listed above.