Ring network and data transmitter

• US 7,133,936 B2
• Filed: 10/05/2001
• Issued: 11/07/2006
• Est. Priority Date: 10/05/2000
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Mizuguchi, Yuji, Katta, Noboru, Yasui, Nobuhiko, Takahira, Yutaka, Sakai, Takahisa, Kawada, Hirotsugu, Kurosaki, Toshihiko
• Primary Examiner(s): Najjar, Saleh
• Assistant Examiner(s): WANG, LIANG CHE A
• Application Number:
  US10/398,377
• Publication Number:
  US 20040088436A1
• Time in Patent Office: 1,859 Days
• Field of Search: 709/251, 709/222, 709/248, 709/249
• US Class Current: 709/251
• CPC Class Codes: H04L 25/062 Setting decision thresholds using feedforward techniques only
• CPC Class Codes: H04L 25/066 Multilevel decisions, not including self-organising maps
• CPC Class Codes: H04L 25/085 Arrangements for reducing interference in line transmission systems, e.g. by differential transmission
• CPC Class Codes: H04L 25/4919 using balanced multilevel codes H04L25/4927 takes precedence

Abstract

A ring-shaped network quickly performs initialization even when a plurality of data transmission apparatuses are connected thereto. Each data transmission apparatus outputs received data to a device connected thereto while performing establishment of clock synchronization based on the received data, and when synchronization is established, it resends the received data. Further, when synchronization of the connected device is established, it sends data supplied from the connected device. Further, a master data transmission apparatus outputs data at turn-on of power or immediately after reset, and a next-stage slave data transmission apparatus receives the data to establish synchronization, and resends the received data when synchronization is established. Thus, synchronization of all the data transmission apparatuses is established while making a round of this data, and then synchronization of devices connected to the respective data transmission apparatuses is established.

Claims

1. 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.

2. A data transmission apparatus as defined in claim 1, wherein said connected device synchronization detector is operable to receive the data from the device and to reproduce a device clock that is synchronized with the data from the device.

3. A data transmission apparatus as defined in claim 2, wherein said connected device synchronization detector is further operable to count the device clock that is reproduced from the data from the device, and the data clock that is reproduced by said synchronization detector based on the data received via the transmission path, for a predetermined period of time, to detect the establishment of synchronization of the device.

4. A data transmission apparatus as defined in claim 2, wherein said connected device synchronization detector is operable to receive the data from the device and to detect a data frame including the data, to detect the establishment of synchronization of the device.

5. A data transmission apparatus as defined in claim 1, wherein said connected device synchronization detector is operable to receive the data from the device and to detect a data frame including the data, to detect the establishment of synchronization of the device.

6. A data transmission apparatus as defined in claim 1, wherein said connected device synchronization detector is operable to count a clock that is inputted in synchronization with the data from the device, and the data clock that is reproduced by said synchronization detector based on the data received via the transmission path, for a predetermined period of time, to detect the establishment of synchronization of the device.

7. A network comprising:

a plurality of data transmission apparatuses, each being operable to transmit data via a transmission path by assigning at least one bit of the data as one data symbol to a signal level, said plurality of data transmission apparatuses being connected to one another via the transmission path to form a multi-staged ring-shaped network; and

a plurality of data devices, each being connected to a corresponding one of said plurality of data transmission apparatuses,

wherein each of said data transmission apparatuses is operable to receive, and to supply said corresponding data device, with data,

wherein each of said data devices is operable to process the data supplied by said corresponding data transmission apparatus and to output a result of the processing to said corresponding data transmission apparatus,

wherein one of said data transmission apparatuses is a master data transmission apparatus, while every other data transmission apparatus is a slave data transmission apparatus,

wherein each of said at least one slave data transmission apparatus is operable to receive, from the transmission path, data outputted from a data transmission apparatus connected in a previous stage, to establish a clock synchronization, to output the received data to said corresponding data device, and to resend the received data to the transmission path,

wherein each of said at least one slave data transmission apparatus is further operable to output the result of the processing of said corresponding data device to the transmission path after the clock synchronization of said corresponding data device is established, and

wherein each of said plurality of data transmission apparatuses comprises;

a synchronization detector operable to establish the clock synchronization based on the received data and to reproduce a data clock;

a connected device synchronization detector operable to detect establishment of the clock synchronization of said corresponding data 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 said corresponding data device and select data supplied from said corresponding data device for output to the transmission path when said connected device synchronization detector detects the establishment of the clock synchronization of said corresponding data device, and

wherein said at least one slave data transmission apparatus operates in synchronization with a clock of said master data transmission apparatus.

8. A network as defined in claim 7, wherein each of said at least one slave data transmission apparatus is operable to output data to the transmission path only when establishment of the clock synchronization is completed.