Abstract: The inter-bus system provides the communication interconnection between communication systems to form a large telegraph packet switching exchange for example. The fast inter-bus system uses an RS-485 interface, however, the specific protocol used has particular speed advantages. The inter-bus system consists of a bus converter for each communication system interconnected by a bus involving 16 data bits, a pair of parity bits, clock, abort, transmit active, address strobe and grant return paths. The bus converters are chained by a grant link arrangement. The grant link is used to carry a grant pulse which is passed on around the chained bus converters to identify the master converter for an inter-bus system transfer. When the grant pulse is received by a bus converter wanting to transmit, that bus converter breaks the chain and performs the transmission required. When the transmission is complete the completing bus converter surrenders its master state by generating the grant pulse.

Abstract: A data transmission system having a number of control devices connected by at least one clock-control transmission loop operated directionally dependent insures that a data signal intended for a group of control devices in the system is actually received by all of the intended control devices. The control device emitting the signal adds an entry preceding the data portion of the signal which identifies all receivers in the group and which also includes a block start identifier, and also adds a last entry to the data portion of the signal which is the address of the sending control device and a block end identifier. Each control device in the group, upon receiving the signal, copies the signal for possible processing, cancels the block end identifier in the last entry of the received signal, and adds a new last entry which is the address of the receiving control device, and acknowledgement of receipt of the signal, and a new block end identifier corresponding to the cancelled block end identifier.

Abstract: A method and apparatus for transmitting data signals between two control devices connected to a loop transmission system are disclosed wherein data signals are transmitted in the form of signal blocks. In addition to the data signal, each signal block includes a receiver address having a block start identifier which precedes the data signals, and a sender address with a block end identifier following the data signals. In response to the appearance of the block start identifier and the receiver address, the signal block received by a control device is copied in the control device identified by the receiver address. The copying is undertaken for possible further processing. The signal block is then forwarded to the next control device via the loop, with the block start identifier cancelled. Before forwarding, an acknowledgement signal is attached to the sender address. The acknowledgement signal is recognized by the control device which sent the date signals.

Abstract: A loop-type data transmission/reception network system has a plurality of data processing stations and a single data transmission/reception route which interconnects said stations in a loop for transmitting necessary data between the stations, each of the stations comprising: (a) means for detecting a break-down in the data transmission/reception route between the station itself and the preceding station; (b) means responsive to the detection of a break-down in the data transmission/reception route between the station itself and the preceding station by the detection means for transmitting break-down information to the subsequent station; and means for reversing the transmission direction in the data transmission reception route in accordance with the break-down information transmitted by the break-down information transmitting means.

Abstract: A loop back system for a loop transmission line allows the whole system to be looped back for addition or removal of a transmission device, without cutting off loops and in exactly the same manner as in ordinary data transfer. A plurality of transmission devices capable of generating loop-back commands are connected to an active loop and a backup loop. First one of the transmission devices transmits loop-back commands, while second and third ones individually receive the loop-back commands to connect their transmitter sides to both the active and backup loops. This sets up a loop-back condition in each of the transmission devices.

Abstract: An information transmission network in which a plurality of information processing stations are connected in parallel to a bus line is disclosed. Each station has a communication control means and an information processor. Each control means is capable of establishing command over the bus line to the exclusion of all other stations. While command is established, the commanding station can communicate with all other stations. After one sequence of communication, command is transferred. If the station presently in command fails, the failure to transfer command in a predetermined time will be noted and another station with highest priority will assume command. If the station to which command is transferred is not operating properly, the station presently in command will detect a failure of the former station to respond to transfer of command and will thereupon transfer command to another station.