Multiplex communications – Special services – Conferencing
Reexamination Certificate
1997-01-17
2001-08-14
Nguyen, Chau (Department: 2663)
Multiplex communications
Special services
Conferencing
C370S437000
Reexamination Certificate
active
06275474
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a private digital communication apparatus for interconnecting a plurality of interface modules which communicate through a common bus.
2. Description of the Related Art
Apparatus of the type just described above are already known in the literature.
SUMMARY OF THE INVENTION
An object of the present invention is to give a further contribution to this field by providing further improvements in the performances of the apparatus mentioned above, in a particularly simple manner.
Another object of the present invention is so to design an apparatus of the type mentioned above as to be compact, easy to realize and low cost.
According to a first aspect of the present invention, a private digital communication apparatus comprises a plurality of interface modules for communicating through a common bus, means for managing the access of the interface modules to the common bus, the access management means being partially distributed in each of the interface modules.
In further accord with this first aspect of the present invention, each of the interface modules may become a master manager of the bus.
According further to this first aspect of the present invention, the common bus may be a bidirectional two-wire bus.
In still further accord with this first aspect of the present invention, access to the common bus may be carried out through time-division multiplexing.
Still further in accord with this first aspect of the present invention, the interface modules may have a pulse code modulation (PCM) interface in order to be able to make outside connections.
In accordance still further with this first aspect of the present invention, the interface modules each comprise a line interface connected to the common bus, a PCM interface, a switching module connected to the line interface and to the PCM interface, an access control module for driving the line interface, a microprocessor for driving the switching module, the PCM interface and the access control module. Additionally, a watchdog module may be included for connection to the bus and be driven by the microprocessor.
According to a second aspect of the present invention, an integrated circuit comprises a line interface connected to a bus, a PCM interface, a switching module connected to the line interface and to the PCM interface, and an access control module driving the line interface.
Advantageously, according to the invention the handling of the access has been partially distributed in each of the interface modules connected to the bus. Despite this, all the modules are similar to each other. This particularly simplifies the construction of these modules.
Each of the modules present on the bus may become the bus master manager. According to the situation of the connections present at a given instant and according to the rules established by the access manager (distributed among the various modules) it is decided who is the master module.
Such apparatus is of multipoint type, uses a two-wire cable as a bus and the access to the bus is carried out through the time division (TDMA) technique.
The various interface modules have a PCM connection to be able to be connected with the outside, i.e. it is possible to connect telephone sets, to establish connections to external public lines and to various services such as telefax, minitel, computers, printers, etc., and to whatever else has a PCM interface and is outside the private digital communication apparatus of the invention. In this way the modularity of the apparatus is maximum, different peripheral apparatuses can be connected to the same interface modules.
Therefore, special care has been taken in the realization of these interface modules to be able to manage in common mode, without obstacles, the access to the bus, still maintaining a particularly compact realization so as to be feasible through an integrated circuit type ASIC (apart from the microprocessor, of course).
A private digital communication apparatus has thus been obtained which is: able to connect quite a number of terminal apparatuses, extremely versatile, highly modular, of compact dimension, without a unique manager (and therefore a further apparatus) for the access to the bus.
REFERENCES:
patent: 3958084 (1976-05-01), Nicholas
patent: 4289932 (1981-09-01), Reed
patent: 4516240 (1985-05-01), Kume et al.
patent: 4797876 (1989-01-01), Ratcliff
patent: 5124983 (1992-06-01), Landez et al.
patent: 5425022 (1995-06-01), Clark et al.
Muriglio Fulco
Perin Franco
Alcatel
Boakye Alexander O.
Nguyen Chau
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