Importance

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Abstract

The present invention provides several apparatus, methods, and computer program products for establishing a data communication link between an interrogation device and the data bus of a vehicle. Specifically, in one embodiment, the present invention provides apparatus, methods, and computer program products that process data transmitted to and from the data bus of a vehicle one bit at a time with minimal delay. The apparatus, methods, and computer program products of this embodiment also prevent propagation of false data to both the data bus and the interrogation device, which is generated by the transmission of data to and from the data bus. The present invention also provides apparatus and methods that reduce the introduction of false data in the form of signal noise onto the data bus of a vehicle when the data bus is not transmitting data to or receiving data from a remote location. In this embodiment, the present invention includes a switch, that in the open position isolates the data bus from a transceiver used to receive external data. The present invention also provides apparatus and methods that establish data communication links between interrogation devices and the data bus of a vehicle by transmitting a data link command alerting the data bus that the interrogation device is attempting to form a data communication link. In some embodiments, both the vehicle and remote interrogation device transmit a heartbeat signal to each other over a data communication link to signify that a data communication link is present. When the heartbeats signal is not received, the vehicle and interrogation device determine that the data link has ended.

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First Claim