Java devices for distributed process control

This paper describes the JDPC-Java Devices for Process Control-a research project of the University of Catania which aims to introduce Java technology in the field of distributed process control. This is a starting point in enhancing the software compatibility and inter-operability of devices of different vendors. To this aim, a general purpose micro-controlled field device architecture is proposed, called the Java microcontrolled device (JMD). It is composed, at the hardware level, of a micro-controller embedding suitable digital and analog I/O lines and a high-speed serial interface. The software level is made of a Java kernel, running upon a native micro-kernel, which provides the application with high-level hardware-independent primitives, including the communication protocol stack and a task scheduler. The JMD embeds a restricted JVM where some features, useless for embedded systems, are removed. In addition, it offers an application programming model based on the definition of a set of tasks which have to be executed each with its period and within its deadline. This is an extension of the classic cyclic or periodic scan model of a PLC program, and allows the programmer to define different parameters for each task to be executed.