The Fermilab accelerator controls networking system

Abstract The Fermilab Accelerator Control System is a highly distributed computer-based control system. The accelerator complex is controlled from widely separated points by a system of three VAX-11/785s, twenty-three PDP-11s of several types and nearly one thousand microprocessors. The host system of VAXs and PDP-11s is centrally located and interconnected by three PCL11-B parallel communication buses and networking software developed at Fermilab. ACNET, Accelerator Control NETwork, is a network protocol designed to provide high performance in data acquisition from and process control of the accelerator complex. This paper presents a description of the ACNET protocol and a discussion of its implementation and performance in the currently operating control system.