| 摘要 |
PURPOSE:To recover a faulty telephone set to its normal state without cutting forcibly a feeder line, by discontinuing the transmission of data from a master device when a telephone set has a fault and meanwhile initializing the faulty telephone set by means of a timer means. CONSTITUTION:Plural telephone sets T1-T3 are connected to a master device ME (not shown in the diagram) via a data line L doubling a feeder line. When a data link is set up, a data transmitting/receiving circut DSR of each telephone set receives the data addressed to own from the ME and transmits an answer data. During such a normal operation, a microcomputer muP functioning as a controller resets a counter CTR for each reception of a data. The ME decides a fault of a telephone set when no answer data is obtained and then discontinues the transmission of data. Thus the muP of each telephone set stops the resetting action of the CTR owing to the discontinuation of receiving data. The CTR produces a signal to initialize the muP when its count value exceeds a fixed level and initializes the telephone set. |
