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DC Power Line Transceiver

IP.com Disclosure Number: IPCOM000077857D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Bekkers, GW: AUTHOR [+2]

Abstract

Data communication between a main frame 8 and a moving carriage 10 through the two bus bars 11 and 12, which deliver the DC power to the carriage is described. The carriage contains the necessary logic to decode and execute the commands from the main frame and, in return, to transmit status information toward it. The main frame, among others, contains the necessary logic to accept a status word and to transmit commands to the carriage.

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DC Power Line Transceiver

Data communication between a main frame 8 and a moving carriage 10 through the two bus bars 11 and 12, which deliver the DC power to the carriage is described. The carriage contains the necessary logic to decode and execute the commands from the main frame and, in return, to transmit status information toward it. The main frame, among others, contains the necessary logic to accept a status word and to transmit commands to the carriage.

Hash filter chokes 13 and 14 isolate the high-frequency data stream from the DC path. Fig. 1 shows the DC current path.

T(1) and T(2) are transistor switches, which short the DC power lines for a short interval of time. This AC disturbance will be contained in between the hash filter chokes and, therefore, can be Picked up at any location on the powerlines. Schmitt triggers, not shown, located in the main frame and on the carriage will sense this disturbance and will generate a logic output.

The line is loaded with the characteristic impedance R in series with a capacitor C. More than one carriage can be operated this way by addressing each one at different time intervals.

Fig. 2 displays the wave form on the DC powerlines. When the line is shorted for a time t, a current will start to flow in the chokes and will generate an extra magnetic field. When the transistors are turned off, this magnetic field will generate a voltage to the line in reverse direction. As long as T(1) and T(2) draw little power from...