The use of industrial type control and monitoring components for a large nuclear fusion experiment

RFX is one of the large nuclear fusion experiments within the framework of the co-ordinated nuclear fusion research programme of the European Community. During the control system design phase in 1986, the increase in power and flexibility of industrial type programmable controllers lead to the decision for a complete physical split of control, monitoring and data acquisition functions according to speed requirements, allowing the exploitation of the relative advantages of both CAMAC and programmable controllers. The 'slow' control and monitoring functions (for about 4000 digital and 200 analog I/O signals with scanning times of ~ 1 second) have been implemented using a series of networked industrial PLCs and personal computers. This has allowed us to choose from a wide range of off-the-shelf hardware and software components for the plant interface and to utilize specialized expertise from the industrial field for the application software implementation. The paper gives the expectations and results gained from this design choice and how it has influenced the decisions for the evolution of the system over the next few years with the utilization of new industrial hardware components. Details are also given regarding the system integration (via the Ethernet network) with the VAX-based CAMAC frontend fast control and data-acquisition system.