| 摘要 |
Disclosed is a stand-alone transmission controller equipped in each of many transmission control stations linked to form a looped data transmission system with the intention of implementing reliable data transfer on a stand-alone basis between optional stations. The controller consists of a signal detecting circuit which detects the presence or absence of a line employment permission signal on the transmission line, a transmission control circuit which sends out a line employment permission signal in response to the absence of the line employment permission signal from another station as detected by the signal detecting circuit on condition that the first station has the loop control priority, a transmitting control circuit which responds to the detection of a line employment permission signal from a station having the loop control priority to send out transmission data together with the detected signal on condition that the station has data to be sent, a reception control circuit which receives transmission data sent through the looped data transmission system and destined to the receiving station and sends out reception data with reception acknowledgement to the sending station appended thereto, a transmission clock pulse synchronizing circuit which synchronizes the reception clock pulse to the transmission clock pulse, and a by-pass circuit which removes a station from the looped data transmission line to form a by-pass of the data transmission system when the station has failed.
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