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Method and coupler for interfacing a portable data carrier with a host processor

  • US 5,149,945 A
  • Filed: 07/05/1990
  • Issued: 09/22/1992
  • Est. Priority Date: 07/05/1990
  • Status: Expired due to Term
First Claim
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1. A method for interfacing a portable data carrier with an asynchronous receiver transmitter for asynchronous data transmission via a signal coupler adapted to receive the portable data carrier in an associated connector comprisinggenerating a carrier present signal CRD PRS and a clear to send signal CTS upon insertion of the portable data carrier in the connector adapted to receive said carrier;

  • generating a request-to-send RTS signal from said asynchronous receiver transmitter after receipt by the asynchronous receiver transmitter of a clear to send CTS signal;

    generating a card on CD ON signal in response to the request to send RTS signal from said receiver transmitter;

    generating a card voltage signal CRD VCC to be applied to the portable data carrier in response to said CRD ON signal; and

    transmitting and receiving data between said receiver transmitter and portable data carrier in response to said generated signals and insertion of a data carrier into the connector, said step of transmitting and receiving data including the step of echoing data from the receiver transmitter to allow said receiver transmitter to receive its own transmission and detect errors in communication on a character by character basis and allow a character error to be acted upon prior to the transmission of the next character.

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