Data processing: measuring – calibrating – or testing – Testing system – Including specific communication means
Reexamination Certificate
2002-04-08
2004-02-24
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Testing system
Including specific communication means
C709S206000, C709S250000, C709S217000, C710S305000, C714S043000
Reexamination Certificate
active
06697756
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for determining filter masks for relevance testing of identifiers which are able to be transmitted by way of a communication network in messages to a communication means, comprising the following steps:
determining relevance identifiers relevant for the communication means, and
determining irrelevance identifiers irrelevant for the communication means.
Moreover, the invention relates to such a generating module.
In communication networks messages are frequently transmitted to numerous destination communication means in so-called broadcast methods. The receiving destination communication means must therefore determine whether a message is relevant for them using an identifier contained in the respective message, generally binarily encoded, as for example a destination and/or source address, for the content of the message. Typical examples of this are bus systems in which the bus participants all receive messages transmitted by way of a bus.
In order to free the principal functional groups of a communication means, for example its central processor and/or central process or processes from filtering assignments, more particularly in the case of bus systems test means for the relevance testing of identifiers are provided in their transmitting and receiving modules which are responsible for transmission and reception of the messages, and such test means test the incoming identifiers using filter masks to determine or find their relevance. If such an identifier stands up to a comparison with one of the filter masks, that is to say it is a question of relevance identifier, the respective message is passed on to the principal functional group of the communication means but otherwise rejected. Test means, which are preferably realized by hardware or hardware-like software, are for example provided in transmission and reception modules for controller area network (CAN) buses, i. e. as CAN controllers. However, they may also be employed in a software process responsible for transmission and reception.
However, the number of the memory locations provided in a transmitting and receiving module is limited so that it is not possible to install a respective filter mask, for instance a binary code identical to them, for each relevance identifier. Furthermore, the test task becomes involved, if a long list of filter masks has to be gone through for testing one identifier.
It would be possible to combine several filter masks together as a combination filter masks, which is passable by several relevance identifiers associated with the respective initial filter masks. Those positions at which the respective initial filter masks differ, are marked as free positions or “don't care” positions in the case of a combination filter mask made up of such filter masks. However, combination filter masks with free positions are frequently able to be passed by (i.e. are transparent to) irrelevance identifiers so that messages, which are irrelevant for the respective communication means, must be processed by the principal functional component group thereof.
SHORT SUMMARY OF THE INVENTION
One object of the invention is to determine a minimized number of filter masks for relevance testing of identifiers, which may be transmitted to a communication means by way of a communication network in messages.
A further object of the invention is to ensure that using the filter masks the irrelevant identifiers may be filtered out by the filter masks in a optimum manner.
In order to achieve these and/or other objects appearing from the present specification, claims and drawings, in the present initially mentioned method the following steps are provided for:
determining at least one initial filter mask in each case for each relevance identifier, which is not passable for the respective relevance identifier and is not passable for the irrelevance identifier,
combining at least two initial filter masks as a combination filter mask, which is passable for the respective relevance identifier associated with the respective initial filter masks, and
testing the combination filter mask, same being retained instead of its respective basic initial filter masks, if all irrelevance identifiers are able to be masked with the combination filter mask or being rejected, it is passable for at least one irrelevance identifier.
For achieving the object of the invention a generating module is also provided, which is provided with means for performing the steps.
The combination filter mask is no longer determined and employed in a more or less random manner, and is now determined on the basis of systematic combination of initial filter masks and testing of the respectively produced combination filter mask as regards non-passability for the irrelevance identifiers so that the irrelevance identifiers are able to be filtered out not only by the initial filter masks, but also by the combination filter mask in an optimum manner.
Further advantageous developments of the invention are defined in the claims.
It is an advantage for combination filter masks to be formed from initial filter masks and/or combination filter masks and to be retained or rejected following testing with the irrelevance identifiers until at least one predetermined interrupt criterion is reached, and more particularly until no further combination filter mask can be produced, which is unpassable for all irrelevance identifiers or until the number or, respectively, sum of combination filter masks and of initial filter masks not replaced by such combination filter masks has reached a predetermined value. The number of the combination filter masks and of the initial filter masks not replaced by them is accordingly minimized.
To the extent that for instance a desired number of the combination filter masks and of initial filter masks not replaced by such combination filter masks can not be reached, that is to say no (further) combination filter mask can be formed, which is not passable for all irrelevance identifiers, there is a provision such that at least one combination filter mask is formed from the initial filter masks and/or the combination filter masks and is retained instead of same, which is passable for at least one irrelevance identifier.
In keeping with such an advantageous form of the invention in the case of a selection of at least two combination filter masks, which are formed from initial filter masks and/or combination filter masks and are passable for at least one irrelevance identifier, that combination filter mask is selected and retained, which is passable for a smaller number of irrelevance identifiers and/or is passable for those irrelevance identifiers, which are transmitted with a lower frequency of occurrence probability in the communication network. Thus the impairment of a communication system is minimized, which would otherwise be caused by an undesired transparency for one or more irrelevance identifiers.
It is convenient for the combination filter masks to be passable for at least one irrelevance identifier only to be formed and retained until the sum of combination filter masks and of initial filter masks not replaced by such combination filter masks reaches a predetermined value. Therefore only as many combination filter masks passable for irrelevance identifiers are formed as is absolutely necessary.
It is an advantage in the case of a particularly preferred form of the invention to have a provision such that the initial filter masks are made into a grouped sequence, that the filter masks of the sequence are respectively combined with the respectively following filter masks in the sequence to give respective combination filter masks and the respective combination filter mask in lieu of the filter mask on which they are based is retained, it is not passable for all irrelevance identifiers. In principle other methods of proceeding are however possible, for example one in which the combination filter masks are formed from randomly selected initial filter masks.
In the case of the step by st
Schelling Helmut
Wettstein Horst
Barlow John
Browdy and Neimark , P.L.L.C.
Le John
Vector Informatik GmbH
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