Multiplex communications – Diagnostic testing – Fault detection
Reexamination Certificate
1997-11-10
2001-05-01
Hsu, Alpus H. (Department: 2662)
Multiplex communications
Diagnostic testing
Fault detection
C370S395430, C370S440000
Reexamination Certificate
active
06226268
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a communication system constituted by a data processing center, data generating sources and data receiving devices and communication network linking these, in the case where the data generating sources or data receiving devices are arranged in linear fashion.
BACKGROUND ART
The present invention relates to a communication device employed in a communication system whereby a data processing center and data generating source are linked, in the case where data generating sources are arranged linearly; typical examples of such a communication system in which data generating sources are arranged linearly include a road management system, railway management system, sewer management system, airfield management system, river management system, or underground railway management system.
In a road management system, a management center is provided within the management zone and video cameras and/or vehicle sensors etc. are disposed along the roads in the management zone, the information from these being collected at the management center. Also, electro-optic display panels are disposed along the roads. Information concerning accidents and/or congestion from adjacent management zones is collected at the management center and evaluation of various types is performed using these items of information and the information of the management zone in question; as a result, various kinds of guidance including congestion information etc. are displayed on electro-optic notice boards, thereby performing traffic management.
Taking the example of such a road management system, conventionally, information was collected by connecting an information generating source and the center by a one-to-one communication line, and guidance was displayed on the electro-optic notice board.
Such a method suffered from the problem of lack of flexibility owing to the following.
For example, if it was desired to add a new camera in a road management zone, construction work had to be undertaken to lay the communication line to the management center from the point where the addition was made. The same problem arose if it was desired to move a camera.
Roads constitute infrastructure that is used for a long period. New and superior monitoring devices make their appearance from time to time. Thus, there is the problem that construction work for laying communication lines arose every time a new type of device was introduced.
Although monitoring is performed by machines insofar as it can be, monitoring by human beings having the five senses may still be necessary. This is the case when slight changes of sound or changes in the atmosphere etc. are to be monitored. These may necessitate patrolling by human beings. In such cases, the monitoring staff have to perform monitoring by patrolling by carrying portable terminals. The monitoring staff need to communicate with the center by their portable terminals from time to time. With the conventional method, preparatory work was necessary to arrange connectors at various locations along the road, these connectors being linked to the center by communication lines. This was not particularly practical.
This information that it was desired to send was of various types, ranging from large amounts of information for which real-time characteristics were required such as video or small quantities of information that did not require real time characteristics, such as monitoring data. It is desirable for these to be integrated and sent by a number of cables if possible.
A further problem with the conventional method was that communication became impossible if there was some fault in the communication device or communication line.
Thus, the conventional system suffered from inflexibility in regard to alterations such as addition or movement of data generating sources or installation of temporary data sources. It also lacked the capability of being able to freely adapt to transmission data of various types such as ITV image data, computer data, or audio data etc. and to send these various types of data in integrated manner. Furthermore, while self-recovery would be desirable in the event of occurrence of a fault, such a function cannot be expected with the conventional system in which data generating sources and the center are connected by cable. Furthermore, from the point of view of infrastructure, there are many problems with the conventional system in that the communication system must be flexibly adapted to alterations over a long period.
An object of the present invention is to realize a communication system wherein the above problems can be solved, which has considerable flexibility, which can cope with data of various types, which can also cope with faults, and which can flexibly cope with future improvements in equipment.
DISCLOSURE OF THE INVENTION
The present invention is characterized by comprising: a plurality of node devices arranged in a distributed fashion in a plurality of locations; one or a plurality of local communication terminals connected to each of the node devices; communication channel means for connecting the plurality of node devices in series; and a center device to which a starting end and a terminal end of the communication channel means are connected; in which the center device sends data for each local communication terminal to the communication means and each of the node devices receives the data and extracts, from this data, data for a local communication terminal connected to the node device in question, and thereby outputs this data to the local communication terminal in question.
The present invention is also characterized by comprising: a plurality of node devices arranged in a distributed fashion in a plurality of locations; one or a plurality of local communication terminals connected to each of the node devices; communication channel means for connecting the plurality of node devices in series; and a center device to which a staring end and a terminal end of the communication channel means are connected; in which the center device sends cell-formed data for each local communication terminal to the communication means and each of the node devices receives the cell-formed data, and extracts, from the received cell-formed data, cell-formed data for a local communication terminal connected to the node device in question, and thereby outputs this cell-formed data to the local communication terminal in question.
Further, each node device may comprise multiplexing transmission means whereby data from the local communication terminal connected to the node device in question are multiplexed with data from the communication channel means downstream and sent to the communication channel means and the center device may collect data from each local communication terminal by receiving data sent to the communication channel from the multiplexing transmission means.
Also, the center device and each node device comprise a transmitter and a receiver, and perform cell transfer with the communication channel means through the transmitter and the receiver.
Further, alteration of logical identifier of the cells is not performed at the node devices.
Also the node devices comprise switch element means wherein cells from the local communication terminal and cells from the upstream center device or node device are mixed without overlapping and are sent to the downstream center device or node devices.
Cell transmission from the node devices to the communication terminal is effected by means of a logical identifier that is permanently allocated to the node device and the communication terminal and is effected by copying the cells at the node device.
When a node device detects a fault by the cessation of transmission of cells from the upstream center device or node device, it transmits a fault cell bearing its own identifying information by a specified virtual communication channel to the downstream center device or node device.
Alternatively, a node device may constantly send with fixed time interval a fault monitoring cell carrying it
Kunikyo Tomoo
Nogami Kazuo
Obara Keiichi
Ochiai Tamiya
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Ho Duc
Hsu Alpus H.
Kabushiki Kaisha Toshiba
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