Real-time communication in the factory automation

Manufacturing systems implemented in the factor have shown that a reduced protocol profile must be adopted when low implementation costs and improved response time for message transfer must be guaranteed. To obtain such performance data a prototype network, CIMNET, was developed for testing purposes. Since the main requirement was to save those investments already made in installing Ethernet broadband networks inside the factories, and previous studies showed that in most cases the carrier-sense multiple-access/collision-detection (CSMA/CD) approach offers good performance despite its nondeterministic nature, a prototype architecture was developed using the CSMA/CD technology. This solution was adopted rigorously following the CNMA protocol profile specification. Performance measurements have been carried out on most MMS protocols and are presented. Fieldbus solutions are analyzed and discussed in order to cope with time critical applications found both in the discrete and continuous process control environment