초록 ▼

A communications terminal for use with a programmable controller to permit transmission of status and control information between that programmable controller and a plurality of programmable controllers having similar communications terminals associated therewith and connected in a communications lo

A communications terminal for use with a programmable controller to permit transmission of status and control information between that programmable controller and a plurality of programmable controllers having similar communications terminals associated therewith and connected in a communications loop. The communications terminal permits one programmable controller to utilize signals originating in other programmable controllers and to provide asynchronous time division multiplexed signals to other programmable controllers via a shielded, twisted-pair conductor to control devices connected to those other programmable controllers.

대표청구항 ▼

A terminal for providing real time intercommunication of digital data between an associated programmable controller and N other programmable controllers, each of which is associated with a similar terminal, said terminals interconnected in at least one closed loop by transmission of N+1 frames of se

A terminal for providing real time intercommunication of digital data between an associated programmable controller and N other programmable controllers, each of which is associated with a similar terminal, said terminals interconnected in at least one closed loop by transmission of N+1 frames of serial digital data which continuously circulate around said loop, each of said frames being identified with one and only one of said other programmable controllers, each of said frames being updated with information from the N other terminals in the loop as it makes one complete cycle of the loop and each of said frames updating the programmable controller with which it is identified when received by the terminal associated therewith, said terminal comprising, in combination: receiving means connected to said loop for receiving therefrom input frames of digital data containing one or more data bytes of information relating to programmable controllers in said loop; transmitting means connected to said loop for transmitting output frames of digital data thereto; first buffer memory means for storing a frame of data; first control means connected to said receiving means and first buffer memory means for transferring data from said receiving means to said first buffer memory means; second buffer memory means connected to said associated programmable controller for delivering to said associated programmable controller bytes of stored data received from the frame of serial digital data associated with the terminal and which were originated by other programmable controllers thereto, the delivery of said stored data being under control of said associated programmable controller; third buffer memory means connected to said associated programmable controller for receiving bytes of updated information therefrom for transmission to said other programmable controllers in frames associated with said other programmable controllers; second control means connected to said first and second buffer memory means for transferring bytes of data for said associated programmable controller from said first buffer memory means to said second buffer memory means when the received input frame of digital data is identified with said associated programmable controller; third control means connected to said first and third buffer memory means for transferring bytes of data for said other programmable controllers from said third buffer memory means to said first buffer memory means when the received input frame of digital data is not identified with said associated programmable controller; and fourth control means connected to said first buffer memory means and said transmitting means for transferring data from said first buffer memory means to said transmitting means for transmission of N output frames not identified with said associated programmable controller, said output frames corresponding to said input frames updated with information for N other programmable controllers, said fourth control means transmitting an output frame identified with said associated programmable controller to be updated by said other terminals.