Intelligent network interface circuit
First Claim
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1. An interface circuit for connection to he communications media of a communications network, the combination comprising:
- a protocol machine having a receive section which connects to the communications media to receive messages and having a transmit section which connects to the communications media to send messages which are written to the transmit section; and
an interface controller connected to the protocol machine and including;
(a) means coupled to said receive section for analyzing a control code in a first message as it is received by the receive section of the protocol machine;
(b) means coupled to said last named means (a) for writing a responsive second message to the transmit section of the protocol machine while the protocol machine continues to receive the first message;
(c) means coupled to said receive section for checking the integrity o the first message when it has been completely received to determine if any errors occurred;
(d) means coupled to said last named means (c) for processing the received first message f no errors are detected; and
(e) means coupled to said checking means (c) or conducting an error recovery sequence if an error is detected;
wherein the transmit section of the protocol machine operates to transmit the second message a preset time interval after the correct receipt of the fit message.
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Abstract
An interface circuit couples a host processor in an industrial control system to a local area communications network. In includes a protocol machine for receiving and transmitting messages on the network and an interface controller which is programmed to implement one or more protocols. As a message is received by the protocol machine, the interface controller anticipates a responsive message which it writes to the protocol machine even as the message is being received. If the message is received accurately, the responsive message is transmitted without delay.
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Citations
4 Claims
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1. An interface circuit for connection to he communications media of a communications network, the combination comprising:
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a protocol machine having a receive section which connects to the communications media to receive messages and having a transmit section which connects to the communications media to send messages which are written to the transmit section; and an interface controller connected to the protocol machine and including; (a) means coupled to said receive section for analyzing a control code in a first message as it is received by the receive section of the protocol machine; (b) means coupled to said last named means (a) for writing a responsive second message to the transmit section of the protocol machine while the protocol machine continues to receive the first message; (c) means coupled to said receive section for checking the integrity o the first message when it has been completely received to determine if any errors occurred; (d) means coupled to said last named means (c) for processing the received first message f no errors are detected; and (e) means coupled to said checking means (c) or conducting an error recovery sequence if an error is detected; wherein the transmit section of the protocol machine operates to transmit the second message a preset time interval after the correct receipt of the fit message. - View Dependent Claims (2, 3, 4)
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Specification