Virtual network adapter

Details Virtual network adapter Virtual network adapter

2000-05-18

2003-05-27

Patel, Ramesh (Department: 2121)

Data processing: generic control systems or specific application

Generic control system, apparatus or process

Optimization or adaptive control

C700S019000, C700S020000, C700S047000, C700S049000, C709S224000, C709S228000, C709S235000, C701S036000, C701S048000, C701S102000, C701S115000, C370S403000, C370S410000, C370S455000, C370S465000

Reexamination Certificate

active

06571136

ABSTRACT:

FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to a method and an electronic circuit arrangement allowing observation of bus-systems and networks. In particular the invention relates to such a method and circuit arrangement not causing electrical or physical constraints and influence to the bus-systems and networks. Still more specifically the invention provides for accessing static bus-systems and networks in particular used by real-time constrained systems and applications.
Buses and networks, used to interconnect real-time electronic systems, are typically defined during system definition and design. The number of bus attachments (loads) and, depending on the type of network to be accessed, the message IDs are predefined during the system definition and can not be altered during system runtime.
Typical representatives for real-time busses are for example networks used in today's modern automobiles, like CAN (Controller Area Network), VAN (Vehicle Area Network), J1939 (specified by SAE, Society of Automotive Engineers) and others. The bus type, topology and the bus-participants are defined by the automotive manufacturer. For several reasons, it is not possible to add on additional devices or units to these busses after the vehicle left the manufacturing plant:
a) The most important factor is safety. Typically providing access to all major Electronic Control Units (ECUs) within the vehicle, safety relevant devices like brake control, engine management and others are connected to the real-time bus-systems;
b) The real-time bus-systems typically provide a limited amount of electrical drive capability, thus limiting the number of devices supported within one network.
c) The number of bus participants and accompanying addresses/message-IDs are kept to a minimum to allow to achieve cost effective systems.
As a consequence to the facts as explained, the busses are not ‘open to public’, thus do not allow adding on new devices at a later time. Only by following this ground rule, the original manufactures will guarantee the vehicle operation to specifications, and most important, are liable to all safety relevant functions.
At present, this circumstance is a strong constraint to the further development of new after-market devices. Restricted by the status of bus access capabilities, these after-market devices are typically not supporting advanced applications demanding access to the vehicle real-time buses and networks.
Typical product examples are today's after-market entertainment systems, navigation systems and telematics devices.
Nevertheless, new emerging applications like on-line services (entertainment, traffic information, etc.), real-time remote diagnostics, advanced ‘dynamic’ navigation systems and others are requiring access to data provided by the diverse vehicle sub-systems (wheel sensors, giro, speed, steering angle).
Due to the limiting facts as explained, this type of new services can only be offered by the original manufactures, provided as an OEM device, developed in cooperation with the vehicle developers.
Unless add-on-device bus access capability is not explicitly provided and built in by the vehicle manufacturer, after market devices are not supported and cannot be allowed to be added to the vehicle domain networks in a ‘plug and play’ manner—an important security issue with potential legal consequences if ignored.
SUMMARY OF THE INVENTION
It is therefore an purpose of the invention to provide access to non-public, restricted networks as typically used in automobiles without the above mentioned shortcomings.
It is a further purpose of the present invention to provide a method having the most important features of the typical bus access methods, as known by standard network adapters.
The present invention describes a principle for an electronic control system providing access capability to protected networks and bus-systems for application processor units, especially used in an automotive vehicle. The active network access tool, in the following called Virtual Network Adapter (VNA) is exercised in a unique virtual manner, in real, the VNA network access is performing absolutely passively, thus not influencing the network neither logically nor physically, in particular there is no electrical influence.
Like standard bus-adapters/controllers, the VNA is featuring two access ports connecting to the external electronic systems. The primary side is accessing the protected real-time network in focus, while the secondary access port of the VNA is interfacing to the Controller System or ECU to be connected to the network.
As is known in the prior art, devices hooked up via standard bus controllers are actively writing to vehicle real-time networks. As for example the message ‘get oil temperature’ will invoke a write command issued to the protected network, requesting the specified information from a specific vehicle domain ECU. Given this typical procedure, as normally executed by standard bus-controllers, therefore, the major requirement of not influencing the network cannot be fulfilled.
It is an advantage of the present invention that, although in reality not actively acting on the real-time network, the VNA system is supporting the major bus access functions like
Data/message on request—invoked by external calling unit (‘active bus access mode’)
Data/message provision on polling—invoked by external calling unit (‘active bus access mode’)
Data/message broadcast—VNA system initiated (‘passive bus access mode’)
The method proposed by the VNA principle is intended to provide access to the messages present at a given time to the most commonly used real-time bus systems. In order not to influence the existing (predefined) network for any reason, neither logically nor physically, standard bus controllers, using the typical arbitration and bus access procedures cannot be used.
As a consequence, not being able to arbitrate and to logically interfere with the respective bus participants, thus not being able to ‘request’ required data on demand, in the ‘first thought’ leads to the conclusion, not providing the network access appropriate to the applications in mind.
The following important statement will provide the elementary precondition for the applicability of the VNA principle:
Each ECU, attached to a real-time network, will provide data and unit relevant information at the bus-system at a certain point of time. As a reversal conclusion: This fact not being the case would dispose the right for this unit to exist on the bus in the first place. In other words, each unit attached to the network will be providing data to the net, invoked on request by other units (regardless of technique, pooling or event triggered), or self-initiated, as for example triggered by an integrated sensor or any other internal logical event.
In any instance, the data providing messages will be issued and exposed to the network initiated by meaningful events and in adequate incidence.
Exactly this fact is the point of admission for the applicability of the proposed VNA system—and in differentiation to feasibility, any network not showing to this basic attribute and behavior will not be meaningfully supported by the VNA.


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