Multiplex communications – Network configuration determination
Reexamination Certificate
2000-02-04
2004-03-02
Cangialosi, Salvatore (Department: 2661)
Multiplex communications
Network configuration determination
C370S471000
Reexamination Certificate
active
06700877
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for automatic address assignment in a bus system having a plurality of communications subscribers or a bus system having a plurality of communications subscribers which are suitable for automatic address assignment, and to the communications subscribers which can be used in the bus system and/or within the framework of the method.
The communications system here is a bus system in which no means for address assignment, for example electronic or mechanical switches, no means for signal delay, etc., are provided for the communications subscribers themselves.
BACKGROUND OF THE INVENTION
A method for automatic address assignment in which the actual communications subscribers which are connected to the bus each have means for address allocation is conventional. For example, in the automation device S7-300 from SIEMENS Aktiengesellschaft, communications subscribers which are connected to the bus have, for example, electrically active components with which it is possible to bring about a situation for the respective communications subscriber in which a signal sequence which is transmitted by a superordinate communications subscriber is represented at the respective communications subscriber in a different way than in the case of further communications subscribers which may be present on the bus. In this case, it is ensured, for example, that the signal sequence which is transmitted by the superordinate communications subscriber first reaches only as far as the first communications subscriber; this communications subscriber modifies the received signal sequence, derives its own address from it and passes on the modified signal sequence to the next communications subscriber only when the modification of the signal sequence and the derivation of the address have been terminated. The second communications subscriber on the bus adopts the same procedure.
A method for automatic address assignment is also known for a superordinate communications subscriber which has, in each case, a so-called port for communicative connection with other communications subscribers, it being possible for each of the communications subscribers to be connected to in each case one of these ports of the superordinate communications subscriber, the address of the respective communications subscriber being defined implicitly by means of the connection to the respective port. Such star-shaped connections are also referred to as point-to-point connections and can be used, for example, when connecting peripheral equipment to a personal computer.
An automatic address allocation is not currently possible in certain types of communications systems, in particular bus systems, in particular serial bus systems, in which no means for address assignment are provided for the individual communications subscribers.
In addition, owing to the topology, an address, even a default address, may occur only once in a bus system because otherwise it is impossible for the communications subscribers to be identified unambiguously, and thus unambiguous data transmission is impossible.
Furthermore, in the conventional bus systems, it is not possible for a plurality of communications subscribers to be incorporated simultaneously into the bus system. New communications subscribers which are to be added can be recognized in most cases as new communications subscribers by reference to a predefinable default address so that if a plurality of communications subscribers with identical default addresses are added simultaneously, ambiguity occurs which makes simultaneous automatic incorporation of a plurality of communications subscribers impossible. A similar problem arises also when defective communications subscribers are exchanged if a communications subscriber with an address which has already been assigned is connected to the communications system when the exchange occurs.
SUMMARY
An object of the present invention is to provide a method for automatic address assignment in a bus system having a plurality of communications subscribers and/or a bus system having a plurality of communications subscribers which are suitable for an automatic address assignment and/or the communications subscribers which can be used in the bus system and/or within the scope of the method, with which method, bus system and/or communications subscribers the abovementioned problems are avoided.
This object is achieved by providing a method for automatic address assignment in a communications system having a plurality of communications subscribers, at least one of which, referred to below as master, performs a superordinate function. The master transmits for the address assignment, a signal sequence, in the following referred to as preamble. The signal sequence is received by the remaining communications subscribers, referred to below as slaves. Each slave which has not yet been allocated an address immediately transmits a signal sequence in response to the preamble, that slave which is chronologically the last to receive the preamble detects, determined from the fact that no further actions take place in the communications system within a predefined time after the signal sequence which was transmitted by it, that, as viewed from the master, there are no further slaves without address allocation present in the communications system spatially after it subsequently switches into an operating mode B which permits an address-assigning telegram from the master to be received. The address-assigning telegram is used by this slave for address assignment. The further slaves without address allocation, which detect actions in the communications system after their own response, waiting again for the preamble of the master.
This object is also achieved by providing a communications system having a plurality of communications subscribers which are suitable for an automatic address assignment. At least one of the subscribers referred to below as master, performs a superordinate function. The master being capable of transmitting a signal sequence for address assignment, referred to below as preamble. The remaining communications subscribers, referred to below as slaves, which have not yet been allocated an address are capable of immediately transmitting a signal sequence in response to the preamble. Each slave is capable of monitoring the communications system after the reception of the preamble. At least one signal sequence which is transmitted by a slave and is intended for the other slaves is capable of being evaluated as an action in the communications system, the absence of the action in the communications system during a predefinable time period being capable of being evaluated by the respective slave to the effect that there are no further slaves without address allocation spatially after it in the communications system, with the result that the respective slave can be switched into an operating mode which permits an address-assigning telegram from the master to be received, with which address-assigning telegram the address assignment for this slave can be effected.
For the communications subscribers, the object is achieved, on the one hand, by means of a super ordinate communications subscriber, referred to below as master, which is suitable for automatic address assignment in a communications system having other communications subscribers, referred to below as slaves, the master at least being suitable
for transmitting a signal sequence in order to initiate the address assignment, referred to below as preamble,
for receiving a response signal sequence, which can be transmitted via one of the slaves in reaction to the preamble, and
for transmitting an address-assigning telegram to the transmitter of the response signal sequence
and, on the other hand, by means of a communications subscriber, referred to below as slave, which is provided for use in a communications system with automatic address assignment, which can be effected by a superordinate communications subscriber, referred to below as master, in which cas
Lorenz Joachim
Weber Karl
Cangialosi Salvatore
Siemens Aktiengesellschaft
Staas & Halsey , LLP
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