JPS5484908A - Scanning system of subscriber line - Google Patents

Abstract

PURPOSE:To enable to scan the subscriber lines with a simple constitution and control, by sequentially designating the scanning of the scanning matrix line with the shift register controlled with the central control unit. CONSTITUTION:When the signal receiving and distribution unit SRD receives the scanning instruction from the central control unitcc via the SP address bus SPAB, the timing circuit TIM is driven and shift clock is given from TIM to the shift register SR, the state ''1'' of the initial set position of SR is shifted by one bit, the line corresponding to the bit location of ''1'' is driven with the scanning drive section SCNDV, and the scanning line of the scanning matrix circuit SCNMTX is sequentially selected and driven every scanning designation from CC. The read-in signal from the result is fed to the read-in circuit SA and is delivered to the SP answer bus SPWB with the clock from TIM.