Signal transmission control system

A signal transmission control system comprising;

• two individual transmission paths and a plurality of stations each incorporating therein at least signal transmitting and receiving function and self-checking function, one of said stations being connected to primary one of said transmission paths which is usually used for signal transmission and being adapted to serve as a transmission control station for preparing access signals and sending out to said primary transmission path thereby to enable data transmission to be performed among others of said stations, while said other stations are adapted to serve as transmitter and receiver stations coupled to said primary transmission path for performing exchange of data with one another in accordance with said access signals issued from said transmission control station, wherein each of said other stations includes first means for disconnecting the associated station a part of which is constituted by said first means itself from said primary transmission channel to perform the self-checking and second means for holding said associated station in the disconnected state when abnormality is found in said associated station itself, while switching said associated station to the other stand-by transmission path when abnormality is found in said primary transmission path, while said one station serving as the transmission control station includes said first means and third means which is arranged such that upon detection of abnormality either in said self-checking or in said primary transmission path, one of said other stations is caused to serve as the transmission control station in place of said one station for preparing said access signal and sending out to said stand-by transmission path thereby to enable data exchange to be performed among remaining ones of said other stations.

A signal transmission control system including two individual transmission paths, a pair of transmission control stations connected, respectively, to said transmission paths, one of said transmission control stations being set in an operative state, while the other is set in a stand-by state, a plurality of subscriber stations normally coupled to said transmission path to which said control station in the operative state is connected and adapted to execute data exchange with one another in accordance with the access signal produced from said operative control station, wherein each of said subscriber stations is composed of first means for disconnecting the associated subscriber station a part of which is constituted by said first means itself from said operative transmission path when said access signal is unavailable properly within a predetermined time span, second meams for performing self-checking in said associated subscriber station after said subscriber station has been disconnected from said operative transmission path, means for holding said associated subscriber station in the disconnected state when abnormality is detected in said subscriber station as a result of said self-checking, and third means for switching said associated subscriber station to the other of said signal transmission path when no abnormality is found in said associated subscriber station as the result of said self-checking, and wherein upon occurrence of abnormality in the signal transmission, the signal transmission control functions of said operative control station are transferred to said stand-by transmission control station.