A software system for modeling and controlling accelerator physics parameters at the Advanced Light Source

We describe a software system used at the Advanced Light Source for accelerator physics studies and accelerator control. The system consists of a number of Unix processes that can be connected together in modular ways. Processes communicate using messages with a common data format, but processes do not know where their messages come from or go to, making each process easily replaceable by others using different algorithms, measurement techniques, or models. Some of the controls and correction functions we have implemented using the system are closed-orbit correction, continuous tune display, and Fourier analysis of turn-by-turn beam position monitor (BPM) data