D2B divice address initialization by use of default address

Details D2B divice address initialization by use of default address D2B divice address initialization by use of default address

1995-03-13

1997-10-07

Olms, Douglas W.

Multiplex communications

Wide area network

Packet switching

370475, H04L 1240, H04L 2906

Patent

active

056755716

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a single channel communication bus system. The system include a communication bus having a plurality of stations connected thereto, which can communicate with one another via the communication bus and to each other. A unique station address is assigned to each station. The stations include an interface circuit which is adapted to call any destination station, by generating a destination station address of that destination station, and to receive an acknowledge signal. The acknowledge signal is transmitted by the relevant destination station if the station address of said destination station corresponds to the transmitted destination station address. The interface circuit of a station is further adapted to perform an initialisation program. Under the control of the initialisation program, the interface circuit is able to generate and transmit a destination station address more than one time. Such generation and transmission are discontinued upon absence of acknowledge signal. The destination station address which has been generated and transmitted is assigned as the master station address to said station.
2. Related Art
Such a single channel communication bus system is known from the Dutch patent application No. 8900717 which has been published on Oct. 16, 1990. That patent application describes how a new device or station is added to the bus system. Once the station has been switched on, a-software protocol in said station will initialize the procedure to find a unique address for said station. The station address initialisation involves in fact two steps, a first one is choosing an address and the second one is verifying whether said address is unique. In order to find out whether said address is unique, the added station sends a chosen address on the bus to all other stations which are connected to said bus system. Each station which has already been active in said bus system checks whether the address sent by the newly added station corresponds with its own address or not. In the first situation the station, which identifies the address sent by the newly added device as its own, will send back to the newly added station an acknowledge signal. So, if the newly added station receives an acknowledge signal, it can verify that the address chosen by it previously is not unique. As a result, in a second cycle, the newly added station will choose another address different from the first chosen one and the protocol as described hereinbefore will be repeated up to the moment where no acknowledge signal is received by the newly added station. This means no station already has this address chosen by the newly added station and thus this address is unique. As soon as this situation occurs the newly added station will adopt this unique address as its own.
The above described station address initialisation can be used in a D2B system, which for instance has been described in U.S. Pat. No. 4,429,384. From the description of the D2B system in this U.S. Pat. No. 4,429,384 can be deduced that the D2B should perform in a reliable way in a low cost and possible noisy environment. Experience has shown that signals on buses are sometimes deteriorated which as a consequence means that the above initialisation procedure can be ruined. Some station on the bus system may send an acknowledge signal to inform the newly added station that the address send by it is not unique, but if such acknowledge signal is deteriorated then the newly added station will adopt the address as its own, but the address is not unique. As a result communication between these two stations and without other stations will be disastrous, because if one of the two stations is addressed by another station both stations will respond and mostly in different ways because each station might be a total difference type of device. Also in this case no proper initialisation will take place.
Further the Dutch patent application 8900717 discloses that the message including the destination

REFERENCES:
patent: 4429384 (1984-01-01), Kaplinsky
patent: 4661902 (1987-04-01), Hochsprung et al.
patent: 4689786 (1987-08-01), Sidhu et al.
patent: 5187708 (1993-02-01), Nakatani et al.
patent: 5422884 (1995-06-01), Goertz

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