Abstract: The establishment of connections between two subscriber or trunk locations or line terminating groups (TG1 . . . TGm) in a communication switching system in which the individual subscriber or trunk locations or line terminating groups are interconnected on a ring-shaped bus arrangement (BUS 0, BUS 1) are carried out through the application of two computers (SB1 . . . SBn) one of which interacts with or serves the calling subscriber location or line terminating group while the second computer interacts with or serves the subscriber location or line terminating group being called. The transmission of communications signals between subscriber locations or line terminating groups occurs through only one of the two computers.

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 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.