| 摘要 |
PURPOSE:To obtain a question-and-answer type bus system of high reliability by monitoring the synchronizing signals playing the role of question and answer in a sequence monitoring device of a question-and-answer type with an up-down counter thereby detecting the disturbance in the question-and-answer sequence. CONSTITUTION:Since an up-down counter 22 takes no more than either +1 or 0 at the normal time when a slave synchronizing signal SSYC11 is inputted after a master synchronizing signal MSYC10, a flop-flop 31 is not set. Since the up-down counter 22 takes +2 or -1 at the anomalous time when either of MSYC10 or SSYC11 is inputted continuously, the flip-flop 31 is also set to output an anomalous detection signal SQCK. At the anomalous time when MSYC10 and SSYC11 superpose, an AND circuit 28 goes on to set the flip-flop 31, thereby outputting the anormalous detection signal SQCK. Hence, the abnormality of the synchronizing signals is detected simply by adding the simple circuits, and therefore the question-and- answer type bus system of high reliability is obtained. |
