The XSYS Data Acquisition System at Triangle Universities Nuclear Laboratory

We have described a general purpose data acquisition and analysis system for the VAX 11/780. The system runs under VMS and uses commercially available hardware for the bulk of the interface. The code is written almost exclusively in Fortran and uses many software components and ideas from other laboratories. All users share common versions of applications tasks, reducing problems associated with program proliferation and documentation.All event sorting is performed by the event analysis language EVAL. Singles data rates of about 70 KHz use about a third of the available CPU time. This has little or no impact on the response time for the other off-line users. Taking over work from an other facility is a convenient and fast way of implementing a data acquisition system when the computer and interface are identical. This was the case for us with the MBD software and the graphics software. If the hardware configuration is different, however, implementation may be difficult unless one of the programmers is very familiar with the system being installed. The key parts of our system, EVAL and the Z-like data structures, did require modification. They were developed during a three month visit by one of the authors (RVP). Once these foundations were laid, the work of writing the full system could be spread around a number of people. We estimate about 1.5 man years of effort in our system to date.