Communications: electrical – Continuously variable indicating – With meter reading
Patent
1990-06-07
1992-09-22
Yusko, Donald J.
Communications: electrical
Continuously variable indicating
With meter reading
34082577, 379 98, 379345, 370 31, H04Q 100, H04B 320, H04L 516, H04M 1100
Patent
active
051501120
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an interface for use between a first communication unit having a two-wire connection and a second communication unit having a single-wire connection.
BACKGROUND OF THE INVENTION
Such communication units may form part of a device used in the control of a fuel system of an internal combustion engine in response to monitoring exhaust gas composition; the first communication unit having a two-wire connection may be a microcomputer and the second communication unit having a single-wire connection part of the monitoring system.
It is known to control the fuel-to-air ratio of an internal combustion engine in response inter alia to the composition of the results of the exhaust gas with a view to reduction in air pollution, and frequently catalytic oxidation is adapted in order to substantially avoid the discharge into the atmosphere of carbon monoxide resulting from incomplete combustion of the fuel. To this end the exhaust gas is analysed by measurement of its thermal conductivity and its composition expressed as the percentage of carbon dioxide present. With microcomputer control of the fuel system there is a need for supplying to the microcomputer signals characterising the instantaneous actual composition and the corresponding desired composition of the exhaust gas as well as other engine performance parameters. The nature of these signals as regards their levels, input and output impedances and their frequency of transmission have been established by ISO specifications.
When the microcomputer is in a position to transmit data to a communications partner it is desirable that it should be able to do so without delay and a conventional two-wire interface involving direct connection between two wires can result in the computer receiving self-transmitted data which is undesirable for echo suppression.
SUMMARY OF THE INVENTION
The interface of the invention is for use between a first communication unit having a two-wire connection and a second communication unit having a single-wire connection. The interface includes: a comparator whose output is extended to a first of the two-wire connections and has its non-inverting input extended to the single-wire connection for transmitting data signals from the second communication unit to the first communication unit; a transistor connected to the second of the two-wire connections; and, a switching network responsive to the high/low potential of the second of the two-wire connections and the high/low potential of the single-wire connection for controlling transmission through said transistor and for controlling the potential of the non-inverting input of the comparator, whereby when a data signal is transmitted by the first communication unit on the second of the two-wire connections the output of the comparator is at high potential and the first of the two-wire connections is at high potential so that the data transmitted by the first communication unit is not received by the first communication unit on the first of the two-wire connections and when a data signal is transmitted by the second communication unit on the single-wire connection the output of the comparator is at low potential and such transmitted data is received by the first communication unit on said first of the two-wire connections.
An interface in accordance with the invention overcomes the disadvantage of a conventional two-wire to two-wire interface and facilitates rapid transmission of data by the microcomputer while at the same time preventing reception of self-transmitted data.
According to a feature of the invention, the switching network can be formed with the transistors and a plurality of resistors so that the potential at the output of the comparator can be made dependent upon the potentials on one of the two-wire connections of the first communications unit which can be a microcomputer and of the single-wire connection of the communications partner.
BRIEF DESCRIPTION OF THE DRAWING
The invention will be further described by way o
REFERENCES:
patent: 3638183 (1972-01-01), Progler
patent: 4279033 (1981-07-01), Brunelli et al.
patent: 4287589 (1981-09-01), Nakamura et al.
patent: 4398298 (1983-08-01), Van Egmond et al.
patent: 4419752 (1983-12-01), Sonnenberger et al.
patent: 4679227 (1987-07-01), Hughes-Hartogs
patent: 4726034 (1988-02-01), Schillhof et al.
patent: 4841561 (1989-06-01), Hill
Ottesen Walter
Robert & Bosch GmbH
Yusko Donald J.
Zimmerman Brian
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