Modem for effecting full duplex asynchronous/synchronous digital data communications over voice grade telephone link
First Claim
1. For use in a data communications network wherein messages originating from or intended for delivery to a data handling device are transmitted over a communications link, an apparatus for carrying out the transmission and reception of said messages comprising:
- a first data communications port adapted to be coupled to said communications link;
second and third data communications ports, each of which is adapted to be coupled to a respective data handling device and is capable of interfacing asynchronous data communication signals;
a modulator/demodulator unit, coupled to said first and second data communications ports, for transmitting synchronous data communication signals that are coupled to said second port from a data handling device over said communications link via said first data communications port, and for receiving synchronous data communication signals that are received from said data communications link at said first data communications port and coupling said synchronous data communications signals to said second port for delivery to a data handling device coupled thereto; and
a communications control unit, coupled to each of said second and third ports and to said modulator/demodulator unit, for controlling the transmission by said modulator/demodulator unit, via said first port to said communications link, of asynchronous data communication signals that are coupled to either of said second and third ports by a data handling device, and for controlling the delivery of asynchronous data communication signals, received from said communications link at said first port by said modulator/demodulator unit, to a data handling device coupled to one of said second and third ports.
1 Assignment
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Accused Products
Abstract
A modem for interfacing digital data communications between a data processing terminal and a telephone link contains, in the modem front panel, a control switch configuration for effecting automatic dialling of a previously stored telephone number, thereby enabling the automatic placement of a call for either an asynchronous or synchronous terminal which cannot perform modem command language. As an additional feature the modem of the present invention provides the capability of allowing an asynchronous terminal, using the command language of the modem via a first asynchronous interface, to place a call for either a synchronous terminal or an asynchronous terminal which cannot support the modem command language and, as a result, is connected to a second interface. The first interface is coupled to a modem control processor through which communication commands for the operation of the modem are effected. The second interface is coupled directly (thereby bypassing the control processor) to a modulator/demodulator or "data pump" for directly interfacing data between the telephone link and the device that is coupled to the second interface, which device, in effect, takes over control of the communication through that port.
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Citations
38 Claims
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1. For use in a data communications network wherein messages originating from or intended for delivery to a data handling device are transmitted over a communications link, an apparatus for carrying out the transmission and reception of said messages comprising:
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a first data communications port adapted to be coupled to said communications link; second and third data communications ports, each of which is adapted to be coupled to a respective data handling device and is capable of interfacing asynchronous data communication signals; a modulator/demodulator unit, coupled to said first and second data communications ports, for transmitting synchronous data communication signals that are coupled to said second port from a data handling device over said communications link via said first data communications port, and for receiving synchronous data communication signals that are received from said data communications link at said first data communications port and coupling said synchronous data communications signals to said second port for delivery to a data handling device coupled thereto; and a communications control unit, coupled to each of said second and third ports and to said modulator/demodulator unit, for controlling the transmission by said modulator/demodulator unit, via said first port to said communications link, of asynchronous data communication signals that are coupled to either of said second and third ports by a data handling device, and for controlling the delivery of asynchronous data communication signals, received from said communications link at said first port by said modulator/demodulator unit, to a data handling device coupled to one of said second and third ports. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 23, 24, 25, 26, 27, 28, 29, 30, 36)
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14. For use in a data communications network wherein messages originating from or intended for delivery to a data handling device are transmitted over a communications link, an apparatus for carrying out the transmission and reception of said messages comprising:
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a first data communications port adapted to be coupled to said communications link; a second communications port adapted to be coupled to a data handling device; a modulator/demodulator unit, coupled to said first and second data communications ports, for transmitting data communication signals that are coupled to said second port from a data handling device over said communications link via said first data communications port, and for receiving data communication signals that are received from said data communications link at said first data communications port and coupling said data communication signals to said second port for delivery to a data handling device coupled thereto; and a communications control unit, coupled to said modulator/demodulator unit, for controlling the transmission by said modulator/demodulator unit, via said first port to said communications link, of data communication signals that are coupled to said second port by a data handling device, and for controlling the delivery of data communication signals, received from said communications link at said first port by said modulator/demodulator unit, to a data handling device coupled to said second port and including means for storing a plurality of codes, each of which is associated with the address of a respective data handling device with which data communications may be conducted via said communications link; and control switch means, coupled to said control unit, for causing said control unit to control said modulator/demodulator unit to establish a data communications channel over said communications link to a data handling device, the address of which corresponds to one of said plurality of codes, whereby data communication signals from a data handling device coupled to said second port may be transmitted by said modulator/demodulator unit over said channel to said addressed data handling device. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 37)
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31. For use in a data communications network wherein messages originating from or intended for delivery to a data handling device are transmitted over a commmnications link, an apparatus for carrying out the transmission and reception of said messages comprising:
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a first data communications port adapted to be coupled to said communications link; a second communications port adapted to be coupled to a data handling device; a modulator/demodulator unit, coupled to said first and second data communications port, for transmitting data communication signals that are coupled to said second port from a data handling device over said communications link via said first data communicatons port, and for receiving data communication signals that are received from said data commmunications link at said first data communicatons port and coupling said data communication signals to said second port for delivery to a data handling device coupled thereto; and a communications control unit, coupled to said modulator/demodulator unit, for controlling the transmission by said modulator/demodulator unit, via said first port to said communications link, of data communications signals that are coupled to said second port by a data handling device, and for controlling the delivery of data communication signals, received from said communications link at said first port by said modulator/demodulator unit, to a data handling device coupled to said second port and including means for storing at least one code which is associated with the address of a respective data handling device with which data communications may be conducted via said communications link and for examining data communication signals that are coupled to one of said data communications ports for application to said modulator/demodulator unit and controlling the operation of said modulator/demodulator unit in accordance with communication control command signals contained within said data communications signals; and control switch means, coupled to said control unit, for causing said control unit to control said modulator/demodulator unit to establish a data communications channel over said communications link to a data handling device the address of which corresponds a code contained within said at least one code, whereby data communication signals from a data handling device coupled to said second port may be transmitted by said modulator/demodulator unit over said channel to said addressed data handling device. - View Dependent Claims (32, 33, 34, 35, 38)
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Specification