Precision Position Control and Monitoring via CAMAC

Devices such as targets and collimators installed in experimental beam lines of the Fermilab Proton Accelerator require precise remote positioning and monitoring-under computer control. Since September, 1973, these and similar applications have been handled by a CAMAC Target Position Controller/Monitor module designed by the Beam Systems Control Group. Numerous features have been incorporated into hardware and software to assure position and input data integrity, and to eliminate hunting, gear-train backlash errors, and direction-change ambiguity. The module controls the device's drive motor via relay closures. Data inputs for the monitoring function consist of a pulse-train generated by a shaft encoder, plus limit and reference switch contacts. Resolution is 16 bits (~1 part in 65,000) or 15 bits either side of center. In addition to its normal positioning functions, the module has found application in facilities which provide precision, on-the-fly, computerized magnetic-field mapping, for programming, monitoring, and policing the motions of a large, multi-arm spectrometer, and as a component in computerized laser alignment equipment.