Performance evaluation of automation systems for the real time control of blowing machines

This paper reports on some results obtained from the study of an innovative automation system for blowing machines producing PET bottles. As the operation of this kind of machines has some critical timing requirements, the traditional solution for the automation system is based on the use of a dedicated programmable logic controller for real time control and on a personal computer for supervision and monitoring purposes. The new proposal, which makes use of an industrial type personal computer as unique "intelligent" device, is particularly attractive because it could lead to both performance improvements and cost savings. In both the types of automation systems, the connection with sensors/actuators distributed on the machine is realized by means of a profibus DP fieldbus network. After a description of the structure of both the automation systems, the paper analyses their performances. The results are then compared with those obtained in practice during some operational sessions of the blowing machines.