Distributed control of manufacturing cells in a Unix environment

The control of manufacturing cells plays a pivotal role in CIM, to provide inter-device communication and process control functionality. The recent availability of Unix systems for the high end PC market and the Intel 80386 and 80486 processors offers a range of new opportunities in shopfloor control. There are several reasons why Unix systems are suitable for the development of distributed control systems, primarily their support for communication networks and the recent availability of windowing systems for Unix. This paper describes a control system developed to control an integrated manufacturing cell across an Ethernet LAN, under the AIX operating system. A graphical user interface was developed for the X Window System. The control software was written in C, on a modular basis, utilizing both AIX system calls and an interface to the X library of functions. The software, being both network transparent and device independent, allows control of the cell from any networked display terminal and demonstrates the suitability of a Unix environment as a tool, in the area of the distributed control of manufacturing operations.