Receiver particularly for a meter-bus

• US 7,973,561 B2
• Filed: 04/05/2006
• Issued: 07/05/2011
• Est. Priority Date: 04/05/2006
• Status: Active Grant

• Current Assignee: Networked Energy Services Corporation (Cedrus Enterprises Holding SAL)
• Original Assignee: Echelon Corporation (Renesas Electronics Corporation)
• Inventors: vanRuymbeke, Gilles, Robinson, Andrew
• Primary Examiner(s): Cho; James H.
• Assistant Examiner(s): LO, CHRISTOPHER KWOK YEUNG
• Application Number:
  US11/399,051
• Publication Number:
  US 20070239318A1
• Time in Patent Office: 1,917 Days
• Field of Search: 455/33, 455/34, 455/418, 455/557, 379 56- 58, 379/61, 379/63, 379/89, 607 27- 28, 607/30, 607/32, 607/37, 607 8- 9, 326/26, 326/30, 326 81- 83, 326 86- 87, 327/94, 327/95, 327/96, 327/538, 327/539, 327/108, 327/109, 327/333, 330290-307
• US Class Current: 326/82
• CPC Class Codes: G01F 15/063 using electrical means

Abstract

A receiver particularly suited for an M-BUS is described. During transmission, the receiver is disabled. After each transmission, nodes and states in the receiver are set to prepare the receiver to receive a signal. Once data is sensed, a feedback loop clips the input signal to the receiver to limit the swing of the input signal. The line of the power supply at the lower potential is modulated, rather than modulating the line at the higher potential, for the transmission of data.

Claims

1. A receiver for sensing current changes on a bus where data is transmitted on the bus by modulating a voltage on the bus, comprising:

first means coupled to the bus for converting the current changes on the bus to an input signal;

second means for amplifying the input signal coupled to the first means;

a pair of capacitors each having a first and second terminal, coupled in series between the first means and second mean the first terminal of one of the capacitors coupled to received the input signal from the first means and the second terminal of the other capacitor coupled to provide the input signal to the second means; and

a gating circuit activated by transmissions on the bus, for disabling the receiver during transmissions by grounding a node between the pair of capacitors comprising the second terminal of the one capacitor and the first terminal of the other capacitor, and for reestablishing bias points in the receiver following a transmission.

2. The receiver defined by claim 1, wherein the gating circuit includes means for establishing a predetermined polarity after a transmission on a bistable circuit coupled to an output of the second means.

3. The method defined by claim 2, wherein the gating circuit includes means for establishing a predetermined bias at the second capacitor following a transmission.

4. A method for operating a receiver which senses current changes on a bus, where data is transmitted on the bus by modulating a power supply potential on the bus, comprising:

sensing the current changes on the bus;

converting the current changes to an input signal;

capacitively coupling the input signal to an amplifier through a pair of series connected capacitors each having a first and second terminal, the first terminal of one capacitor receiving the input signal and the second terminal of the second capacitor coupling the input signal to the amplifier;

determining when data is being transmitted;

coupling a node between the capacitors comprising the second terminal of one of the capacitors and the first terminal of the other capacitor to ground thereby disabling the receiver when it is determined that data is being transmitted; and

rebiasing the amplifier following the transmission of data.

5. A receiver for operating with a pair of lines which connect the receiver to slave units where power for the slave units is provided over the pair of lines, and where data is transmitted to the slave units by changing a power potential between the pair of lines, and also where data is transmitted from the slave units to the receiver by changing the amount of current drawn by the one of the slave units transmitting data to the receiver, comprising:

a first resistive circuit connected to one of the pair of lines for providing an input signal to the receiver in response to a change in current on the line;

a capacitive circuit comprising a first and second capacitors coupled in series, the first capacitor being coupled to the first resistive circuit for removing a DC component from the input signal;

an amplifier having an input coupled to the second capacitor;

a bistable circuit coupled to an output of the amplifier;

a sensing circuit for sensing the transmission of data to at least one of the slave units, coupled to at least one of the pair of lines;

a clamping circuit coupled to the capacitor circuit and the sensing circuit, for grounding a node between the first and second capacitors thereby substantially preventing the amplifier from sensing the transmission of data; and

a biasing circuit for biasing the input to the amplifier in response to the sensing of data being transmitted, coupled to the amplifier and the sensing circuit.

6. The receiver of claim 5, including a reset circuit for resetting the state of the bistable circuit in response to the sensing of the transmission of data.