Interconnected loop data block transmission system

Abstract

A closed loop transmission system is described in which a plurality of stations have access to each loop to write messages into and read messages from standard-sized message blocks transmitted around the loop. One station in each loop provides regeneration of all message blocks. The various loops are interconnected by switching stations which respond to address information at the head of each message block to selectively switch the block to the interconnected loop. The next required address is always substituted for the current address to simplify address recognition. Alternate and redundant routing are also provided for.

What is claimed is: 
     
       1. A transmission system for transmitting multi-word message blocks of digital data comprising at least three intersecting transmission loops,   each said loop including a plurality of substantially identical autonomous stations responsive only to availability and destination control signals indicating the availability and destination of said message blocks, respectively, said control signals being placed on said loop by any of said autonomous stations for respectively writing message blocks onto and for reading message blocks from that loop, and   a message block switching station at each intersection of said loops, said switching stations each comprising buffer storage means for storing a plurality of said message blocks,   selection means responsive only to said destination control signals for selecting message blocks to be transferred to an intersecting loop,   means for writing the selected message blocks from one of said selected loops into said buffer storage means at the time of arrival thereof, and   means for reading message blocks from said buffer storage means onto the other one of said intersecting message loops in response to said availability control signals on said other one of said loops.     
     
     
       2. The transmission system according to claim 1 further comprising an alternatively usable loop between two loops intersecting the same common loop, and   message block switching means for interconnecting said alternatively usable loop to said two loops to switch message blocks between said two loops without said message blocks traversing said common loop.   
     
     
       3. The transmission system according to claim 1 further comprising at least one redundant loop interconnecting the same stations as one of said transmission loops, and   at least one spare station of said message block switching stations interconnecting said redundant loop to an intersecting one of said transmission loops.   
     
     
       4. A distributed control, loop transmission system for digital data message blocks comprising at least three closed transmission loops,   a plurality of substantially identical autonomous stations on each of said loops, each of said autonomous stations including means responsive to availability signals indicating the availability of said message blocks and placed on the connected one of said loops by any one of said autonomous stations for writing a digital message on that loop in an available message block, and   means responsive to destination signals indicating the destination of the data in said message block and placed on the connected one of said loops by any one of said autonomous stations for reading a digital message block from that loop, and   buffer storage means connected between two of said autonomous stations on different ones of said loops to interconnect the corresponding loops for exchange of digital message blocks therebetween by allowing the data received from one loop to be transmitted in a message block of another loop when the availability signals in said other loop indicate an available message block.     
     
     
       5. A distributed control, loop transmission system according to claim 4 further comprising a resynchronizing unit in each of said transmission loops for closing each of said loops on itself.   
     
     
       6. A distributed control, loop transmission system according to claim 4 wherein said means for writing digital message blocks comprises a shift register in series with said transmission line,   detection means responsive to signals in said register for identifying digital message block starting times, and   means responsive to said detection means for writing data into said shift register.   
     
     
       7. A distributed control, loop transmission system according to claim 4 wherein said closed transmission loops include a plurality of lower level loops each interconnecting a plurality of said stations, and   at least one higher level loop interconnecting all of said lower level loops.   
     
     
       8. A distributed control, loop transmission system according to claim 7 including at least three levels of interconnecting loops, each higher level loop interconnecting a plurality of lower level loops, and   a single highest level loop interconnecting a plurality of next lower level loops.   
     
     
       9. A distributed control, loop transmission system according to claim 7 comprising a bypassing transmission loop interconnecting two of said lower level loops to permit communication between said two lower loops without traversing said higher level loop, and   bypass buffer storage means interconnecting one of said stations on said bypassing transmission loop with stations on said two lower level loops.   
     
     
       10. A distributed control, loop transmission system according to claim 9 wherein said bypass buffer storage means is connected to said one station to intercept messages prior to their delivery to said higher level loop.   
     
     
       11. A distributed control, loop transmission system according to claim 9 wherein said bypass buffer storage means is connected to said one station to intercept messages after their attempted delivery to said higher level loop. .Iadd. 12. A communication system comprising:   a closed master transmission loop;   a system control means that operates in discrete cycles, said master control means producing first and second framing characters at the beginning of each cycle;   an interface means connected to said system control means and said master loop, said interface means including a switch connected in said loop master for transferring said first and second framing into said master loop for tranmission around said master loop;   a plurality of transmission sub-loops, each of said being connected to said master loop by a first interface connected to said master loop, each having a sub-loop control unit connected to saiad first interface, and a second interface connected to said sub-loop control unit and to a separate transmission sub-loop;   each of said transmission sub-loops having a plurality of stations connected thereto, said stations being operable to transmit and receive digital messages;   each of said sub-loop control units having a first storage means for storing messages to be transmitted from its associated sub-loop and a second storage means for storing messages to be received by its associated sub-loop;   a first one of said sub-loop control units being responsive to said first and second framing characters to permit transmission of messages from its first storage means onto said master loop and concurrently producing a third framing character to prevent transmission from the other sub-loop   
     
     
        control units. .Iaddend. .Iadd. 13.  A communication system according to claim 12 wherein each of said interfaces includes a receive register connected to said master loop on one side of the said switch therein and a transmit register connected to the master loop on the other side of said switch; a decoder connected to said receive register for detecting and producing signals upon the receptors of said first, second and third framing characters;   a storage means connected to said transmit register for providing first, second and third framing characters to said transmit register;   and control means connected to said decoder means and said storage means for controlling the sequence of operation thereof. .Iaddend..Iadd. 14. A communication system according to claim 12 wherein each of said sub-loop control units inlcudes means for receiving messages from said interface connected to said master loop;   means for storing said messages from said master loop for one cycle of operation;   and means for thereafter transmitting said messages from said master loop through said interface connected to said sub-loop;   means for receiving messages from said interface connected to said sub-loop;   means for storing said messages from said sub-loop for one cycle of operation;   and means for thereafter transmitting said messages from said sub-loop through said interface connected to said master loop and onto said master loop. .Iaddend.