CODA - A SCALABLE, DISTRIBUTED DATA-ACQUISITION SYSTEM

A new data acquisition system has been designed for physics experiment s scheduled to run at CEBAF starting in the summer of 1994. This syste m runs on Unix workstations connected via ethernet, FDDI, or other net work hardware to multiple intelligent front end crates -- VME, CAMAC , or FASTBUS. CAMAC crates may either contain intelligent processors, o r may be interfaced to VME. The system is modular and scalable, from a single front end crate and one workstation linked by ethernet, to as many as 32 clusters of front end crates ultimately connected via a hig h speed network to a set of analysis workstations. The system includes an extensible, device independent slow controls package with drivers for CAMAC, VME, and high voltage crates, as well as a link to CEBAF ac celerator controls. All distributed processes are managed by standard remote procedure calls propagating change-of-state requests, or readin g and writing program variables. Custom components may be easily integ rated. The system is portable to any front end processor running the V xWorks real-time kernel, and to most workstations supplying a few stan dard facilities such as rsh and X-windows, and Motif and socket librar ies, SamPle implementations exist for 2 Unix workstation families conn ected via ethernet or FDDI to VME (with interfaces to FASTBUS or CAMAC ), and via ethernet to FASTBUS or CAMAC.