PC-based automation systems: an example of application for the real-time control of blowing machines

摘要

Personal computers are nowadays being used even more frequently to implement time critical tasks in (distributed) automation systems. The achievement of such an interesting feature has been made possible thanks to several factors; the most important of them are: the impressive growth of the PC's performances, the availability of real-time operating systems and the introduction of programming languages suitable to develop control tasks. Moreover, the implementation of PC-based automation systems has been favoured by the recent considerable diffusion of field networks, which allow for the realization of manufacturer independent configurations. In this paper, after a general description of the PC-based automation systems, we consider, as an example of application, the automation of blowing machines producing PET bottles. The study, which has been carried out in the framework of a joint research project between the Italian National Council of Research and an Italian firm, was aimed at investigating the possibility of using a PC-based automation system for the blowing machines. The adoption of such a type of system has been carefully evaluated by means of a preliminary theoretical analysis. Then, a test machine has been implemented to collect data and performance figures by carrying out experiments and measures. Finally, the results obtained have been compared with those of an equivalent machine equipped with a traditional automation system based on a Programmable Logic Controller.