Method and equipment for bidirectional data transmission (protocol)
First Claim
1. A method for half duplex bi-directional communication of data, whereby information is transmitted by using a protocol implemented between first and second communicators (KP1, KP2), each comprising a transmitter and a receiver, and whereby the transmission of data is in serial bit form with the time between successive data bit transmission being a period ta and the direction of data signal transmission therebetween is switchable, comprising the steps of:
- generating transmit identification signals by which said first communicator identifies itself as a massage initiating communicator (IKP) prior to transmitting a bit of a data signal;
generating receipt identification signals by which said second communicator identifies itself as a message receiving communicator (EKP) after receipt of a transmitted bit of a data signal;
broadcasting from said first communicator (IKP) a double length start bit (D) representing said first communicator identity at the beginning of each character of the data transmission;
waiting, by said first communicator, a defined time (tc) having about one half the duration of said ta time period;
sending, by said second communicator (EKP) back an echo signal in the form and duration of a single length start bit (B) during the defined time (tc) only after the of the double length start bit (D);
waiting, by the first communicator, for an echo signal after each transmitted data bit of a character;
comparing, by the first communicator, each transmitted data bit with the received echo bit;
breaking off transmission should a mismatch occur between said transmitted data bit and the received echo bit; and
generating signals to remove identification of said first and second communicators as initiating (IKP) and receiving (EKP) communicators.
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Accused Products
Abstract
With this method, a CSMA/CA protocol can be used for the transmission of data by means of infra-red light or radio (or other non-hard-wired transmission media). For this purpose a communicator that has a transmit requirement and has not yet received a bit identifies itself as an initiating communicator, and one that has no transmit requirement but has received a bit identifies itself as a receiving communicator. At the start of data transmission the initiating communicator sends a double length start bit (D) representing its identity and then waits a defined time (tc), during which the receiving communicator sends back an echo in the form of a single length start bit (B). The initiating communicator waits after each bit transmitted for the echo and compares this on receipt with the transmitted bit, its transmission being interrupted after a mismatch. After the data transmission, and provided there is no further transmit requirement, the identities of initiating and receiving communicators are removed.
35 Citations
13 Claims
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1. A method for half duplex bi-directional communication of data, whereby information is transmitted by using a protocol implemented between first and second communicators (KP1, KP2), each comprising a transmitter and a receiver, and whereby the transmission of data is in serial bit form with the time between successive data bit transmission being a period ta and the direction of data signal transmission therebetween is switchable, comprising the steps of:
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generating transmit identification signals by which said first communicator identifies itself as a massage initiating communicator (IKP) prior to transmitting a bit of a data signal; generating receipt identification signals by which said second communicator identifies itself as a message receiving communicator (EKP) after receipt of a transmitted bit of a data signal; broadcasting from said first communicator (IKP) a double length start bit (D) representing said first communicator identity at the beginning of each character of the data transmission; waiting, by said first communicator, a defined time (tc) having about one half the duration of said ta time period; sending, by said second communicator (EKP) back an echo signal in the form and duration of a single length start bit (B) during the defined time (tc) only after the of the double length start bit (D); waiting, by the first communicator, for an echo signal after each transmitted data bit of a character; comparing, by the first communicator, each transmitted data bit with the received echo bit; breaking off transmission should a mismatch occur between said transmitted data bit and the received echo bit; and generating signals to remove identification of said first and second communicators as initiating (IKP) and receiving (EKP) communicators. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Apparatus for half duplex bidirectional data communication with a direction of data signal transmission which is switchable and the transmission of data is in serial bit form with the time between successive data bit transmission being a period ta, said apparatus including first and second communicators (KP1, KP2), both comprising:
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a transmitter for transmitting data signals in response to transmission control signals; a receiver for receiving said data signals in response to receiver control signals, and a control unit connected to the transmitter and the receiver for generating said transmitter and receiver control signals and having a first memory element for identification as an initiating communicator (IKP) and a second memory element for identification as a receiving communicator (EKP);
said control unit receiving a first input (Test) signal and a second input (Loop back) signal such that said first input (Test) is connected to said first memory element, and said second input (Loop back) is connected to said second memory elementsaid control unit further including a means for generating transmit identification signals by which said first communicator identifies itself as a message initiating communicator (IKP) prior to transmitting a bit of a data signal; a means for generating receipt identification signals by which said second communicator identifies itself as a message receiving communicator (EKP) after receipt of a transmitted bit of a data signal; a means for broadcasting from said first communicator (IKP) a double length start bit (D) representing said first communicator identity at the beginning of each character of the data transmission; a means for waiting, by said first communicator, a defined time (tc) having about one half the duration of said time period ta ; a means for sending by said second communicator (EKP) back an echo signal in the form and duration of a single length start bit (B) during the defined time (tc) only after the reception of the double length start bit (D); a means for waiting, by the first communicator, for an echo signal after each transmitted data bit of a character; a means for comparing, by the first communicator, each transmitted data bit with the received echo bit; a means for breaking off transmission should a mismatch occur between said transmitted data bit and the received echo bit; and a means for generating signals to remove identification of said first and second communicators as initiating (IKP) and receiving (EKP) communicators. - View Dependent Claims (12, 13)
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Specification