Patent ID: 6412032
Filing Date: 2002-06-25
Classification: G06F

Abstract:
An interface for a network card that is replaceably attached to an industrial controller to transmit messages sent from the industrial controller to a network and to receive messages from the network for the industrial controller, the interface comprising:a first and second buffer; a valid buffer register holding a value indicating the first or second buffer; a consumer access register holding a value indicating the first or second buffer, or when cleared neither of the first nor second buffers; an electronic computer executing a stored program to: (a) prior to reading one of the first and second buffers: (i) copy a value of the valid buffer register to the consumer access register; (ii) confirm that the value of the consumer access register equals the value of the valid buffer register; (b) upon confirmation, read a buffer indicated by the consumer access register; and (c) upon completion of the reading, clear the consumer access register.