Design of a real-time central data acquisition and analysis system

A computer system is described for real-time data acquisition and servicing of 40 asynchronous inertial guidance system test stations. Some data are received automatically from the small guidance system computers at a maximum rate of eight words per second. Other data are input manually at each station via a mode selector and several 16-position thumbwheel switches. The data are received, partially edited and stored all in real time, and retrieved and analyzed with the highest "time-availability" priority at the time of completion of the guidance system test. The analysis results determine further testing or repair actions for each guidance system. The central computer is a SEL 840-MP, a general-purpose 24-bit, 32K, 1.75-µs cycle-time machine with basic real-time monitor software. The special purpose system is implemented as a software/ hardware interface with the real-time monitor and the test station hardware. A key factor for the real-time data processing is the use of random access blocks on mass storage discs to greatly augment primary memory without seriously degrading total accessing time. This also frees "background" core for off-line programs running in a low-priority interruptable mode and for the analysis programs which do not operate in the real-time mode. A disc allocation and cataloging scheme is presented along with a hardware and software description.