Importance

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Abstract

An on-board diagnostic system which comprises dedicated hardware for performing run-time diagnostics on a computer board having several functional sections. The diagnostic system utilizes a serial token ring network, which preferably has a software-independent, hardware core, comprising a non-intelligent master device and a plurality of non-intelligent slave devices. The master and slave devices are all interconnected via a dedicated serial data bus which operates independently of the on-board CPUs and on-board CPU buses. Each slave device is responsible for monitoring a particular section of the computer board. The master device polls each slave device by activating a corresponding token line on each slave device for a predetermined period of time, one at a time, until the master device is alerted by a slave device that a change of state has occurred in the status signals of that particular section. If there is a change in state for that particular section of the board, the corresponding slave device will begin transmitting data on the serial bus the next time that the Master device activates the token line for that slave device. Once the master device sees this activity on the serial bus, the master device will then maintain the corresponding token line active for a predetermined period of time in order to receive a bit-stream from the corresponding slave device over the serial data bus. Preferably, the bit-stream contains a source address (the address of the slave device sending the message), a destination address (the address or addresses to which the message data is to be sent) and the data which indicates the change. The master device will then transmit the diagnostic data to the particular destination devices indicated by the destination addresses.

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First Claim