Patent ID: 7133936

Claim:
A data transmission apparatus for connection to a ring-shaped network comprising a master data transmission apparatus and at least one other data transmission apparatus via a transmission path, for transmitting data by assigning one or more bits of the data as one data symbol to a signal level, and for connection with a device that is operable to be supplied with data received by said data transmission apparatus, to process data received by said data transmission apparatus and to output a result of the processing to said data transmission apparatus, said data transmission apparatus comprising: a synchronization detector operable to establish synchronization based on data inputted via the transmission path and to reproduce a data clock; a connected device synchronization detector operable to detect establishment of synchronization of the device; and a selector operable to select the data inputted via the transmission path for output to the transmission path when said connected device synchronization detector has not detected the establishment of synchronization of the device and select data supplied from the device for output to the transmission path when said connected device synchronization detector detects the establishment of synchronization of the device, wherein said data transmission apparatus operates in synchronization with a clock of the master data transmission apparatus.