Two-wire dc communication system and transceiver

• US 5,694,109 A
• Filed: 09/04/1996
• Issued: 12/02/1997
• Est. Priority Date: 09/04/1996
• Status: Expired due to Term

• Current Assignee: International Controls and Measurements Corporation
• Original Assignee: International Controls and Measurements Corporation
• Inventors: Nguyen, Andrew M., Morrow, Benjamin V.
• Primary Examiner(s): Mullen, Thomas
• Assistant Examiner(s): TONG, NINA C
• Application Number:
  US08/707,423
• Time in Patent Office: 454 Days
• Field of Search: 340/310.01, 340/310.02, 340/310.06, 340/538, 455/3.3, 236/51, 165/22
• US Class Current: 340/12.33
• CPC Class Codes: H04L 12/2803 Home automation networks
• CPC Class Codes: H04L 12/282 based on user interaction within the home receiver circuitry for displaying additional information being controlled by a remote control apparatus H04N21/42204
• CPC Class Codes: H04L 12/2838 Distribution of signals within a home automation network, e.g. involving splitting/multiplexing signals to/from different paths adaptations of television systems for transmission by electric cable for domestic distribution H04N7/106; hybrid transport H04L12/6418; home network arrangements specially adapted for distribution of digital video signals H04N7/24
• CPC Class Codes: H04L 2012/285 Generic home appliances, e.g. refrigerators

Abstract

Arrangement for dc signaling between a transmitter or transceiver over a single pair of conductors to another transceiver or receiver of similar design. The conductors carry a dc communications voltage at a level V_comm (e.g., 24 to 35 volts dc) and power for the tranceivers, receivers and/or transmitters of the system. The transceiver comprises a microprocessor having a signal input terminal V_in, a signal output terminal V_out, a sensor input circuit coupled to a sensor transducer, e.g., a temperature sensor, and a control output circuit coupled to control an external device, e.g., a furnace relay. A voltage limiting circuit device coupled to the pair of conductors supplies the microprocessor with a supply voltage V_dd at a predetermined level (e.g., 5 volts dc) less than the communications voltage level V_comm. A signal input/output circuit coupled to the pair of conductors and to the microprocessor signal input and output terminals applies incoming pulse signals from the conductors to the input terminal, and applies onto the dc conductors output pulse signals. The output signals have high and low values respectively at the dc communications voltage level V_comm and a predetermined voltage level V_Z2 (e.g., 10 to 12 volts) between the communications voltage V_comm and the supply voltage V_dd. The signal input/output circuit can comprise a zener and a transistor.

Claims

1. A dc signaling transceiver for communicating over a single pair of conductors which carry a dc communications voltage at a level V_comm ;

comprising

(a) microprocessor means having a signal input terminal V_in, a signal output terminal V_out, a sensor input circuit coupled to a sensor transducer, and a control output circuit coupled to control an external device;

(b) voltage limiting means having an input coupled to said pair of conductors to receive said dc communications voltage level V_comm and an output coupled to said microprocessor means to supply thereto a supply voltage V_dd at a predetermined level less than said communications voltage level V_comm ; and

(c) signal input/output means coupled to said pair of conductors and to said microprocessor means signal input terminal and signal output terminal, including means for applying incoming pulse signals from said conductors to said input terminal, and means for applying onto said conductors output pulse signals that have high and low values at said dc communications voltage level V_comm and a predetermined voltage level V_Z2 that is between said communications voltage V_comm and said supply voltage V_dd.

2. A dc signaling transceiver according to claim 1 wherein said signal input/output means includes voltage drop means having a voltage drop establishing said voltage level V_Z2 and controlled switching means coupled in series between said pair of conductors, with a junction of said voltage drop means and said controlled switching means being coupled to said microprocessor means signal input terminal V_in, and with a control terminal of said controlled switching means coupled to said microprocessor means signal output terminal V_out.

3. A dc signaling transceiver according to claim 2 wherein said voltage drop means includes a zener diode having a zener voltage at said voltage level V_Z2.

4. A dc signaling transceiver according to claim 2 wherein said controlled switching means includes a transistor device having a first current-carrying electrode coupled to said junction, a second current-carrying electrode coupled to one of said conductors, and a control electrode coupled to said microprocessor means signal output terminal.

5. A dc signaling transceiver according to claim 4 further comprising a resistor coupled in parallel with said transistor device between said junction and said conductor.

6. A dc signaling transmitter for communicating over a single pair of conductors which carry a dc communications voltage at a level V_comm ;

comprising

(a) microprocessor means having a signal input terminal V_in, a signal output terminal V_out, and a sensor input circuit coupled to a sensor transducer;

(b) voltage limiting means having an input coupled to said pair of conductors to receive said dc communications voltage level V_comm and an output coupled to said microprocessor means to supply thereto a supply voltage V_dd at a predetermined level less than said communications voltage level V_comm ; and

(c) signal output means coupled to said pair of conductors and to said microprocessor means signal input terminal and signal output terminal, including means for applying incoming pulse signals from said conductors to said input terminal, and means for applying onto said conductors output pulse signals that have high and low values at said dc communications voltage level V_comm and a predetermined voltage level V_Z2 that is between said communications voltage V_comm and said supply voltage V_dd.

7. A dc signaling transmitter according to claim 6 wherein said signal output means includes voltage drop means having a voltage drop establishing said voltage level V_Z2 and controlled switching means coupled in series between said pair of conductors, with a junction of said voltage drop means and said controlled switching means being coupled to said microprocessor means signal input terminal V_in, and with a control terminal of said controlled switching means coupled to said microprocessor means signal output terminal V_out.

8. A dc signaling transmitter according to claim 7 wherein said voltage drop means includes a zener diode having a zener voltage at said voltage level V_Z2.

9. A dc signaling transmitter according to claim 7 wherein said controlled switching means includes a transistor device having a first current-carrying electrode coupled to said junction, a second current-carrying electrode coupled to one of said conductors, and a control electrode coupled to said microprocessor means signal output terminal.

10. A dc signaling transmitter according to claim 9 further comprising a resistor coupled in parallel with said transistor device between said junction and said conductor.

11. A dc signaling receiver for receiving communications signaling over a single pair of conductors which carry a dc communications voltage at a level V_comm ;

comprising

(a) microprocessor means having a signal input terminal V_in, a signal output terminal V_out, and a control output circuit coupled to control an external device;

(b) voltage limiting means having an input coupled to said pair of conductors to receive said dc communications voltage level V_comm and an output coupled to said microprocessor means to supply thereto a supply voltage V_dd at a predetermined level less than said communications voltage level V_comm ; and

(c) signal input means coupled to said pair of conductors and to said microprocessor means signal input terminal and signal output terminal, including means for applying incoming pulse signals from said conductors to said input terminal, which output pulse signals have high and low values at said dc communications voltage level V_comm and a predetermined voltage level V_Z2 that is between said communications voltage V_comm and said supply voltage V_dd.

12. A dc signaling receiver according to claim 11 wherein said signal input means includes voltage drop means having a voltage drop establishing said voltage level V_Z2 and controlled switching means coupled in series between said pair of conductors, with a junction of said voltage drop means and said controlled switching means being coupled to said microprocessor means signal input terminal V_in, and with a control terminal of said controlled switching means coupled to said microprocessor means signal output terminal V_out.

13. A dc signaling receiver according to claim 12 wherein said voltage drop means includes a zener diode having a zener voltage at said voltage level V_Z2.

14. A dc signaling receiver according to claim 12 wherein said controlled switching means includes a transistor device having a first current-carrying electrode coupled to said junction, a second current-carrying electrode coupled to one of said conductors, and a control electrode coupled to said microprocessor means signal output terminal.

15. A dc signaling receiver according to claim 14 further comprising a resistor coupled in parallel with said transistor device between said junction and said conductor.

16. A two-wire coupled control system in which a one or more remote transceivers communicate with a main transceiver over a single pair of conductors which carry a dc communications voltage at a level V_comm ;

wherein said main transceiver comprises (a) microprocessor means having a signal input terminal V_in, a signal output terminal V_out, a sensor input circuit coupled to a sensor transducer, and a control output circuit coupled to control an external device;

(b) voltage limiting means having an input coupled to said pair of conductors to receive said dc communications voltage level V_comm and an output coupled to said microprocessor means to supply thereto a supply voltage V_dd at a predetermined level less than said communications voltage level V_comm ; and

(c) signal input/output means coupled to said pair of conductors and to said microprocessor means signal input terminal and signal output terminal, including means for applying incoming pulse signals from said conductors to said input terminal, and means for applying onto said conductors output pulse signals that have high and low values at said dc communications voltage level V_comm and a predetermined voltage level V_Z2 that is between said communications voltage V_comm and said supply voltage V_dd ; and

at least one of said remote transceivers also comprises (d) microprocessor means having a signal input terminal V_in, a signal output terminal V_out, and a sensor input circuit coupled to a sensor transducer;

(e) voltage limiting means having an input coupled to said pair of conductors to receive said dc communications voltage level V_comm and an output coupled to said microprocessor means to supply thereto a supply voltage V_dd at a predetermined level less than said communications voltage level V_comm ; and

(f) signal input/output means coupled to said pair of conductors and to said microprocessor means signal input terminal and signal output terminal, including means for applying incoming pulse signals from said conductors to said input terminal, and means for applying onto said conductors output pulse signals that have high and low values at said dc communications voltage level V_comm and a predetermined voltage level V_Z2 that is between said communications voltage V_comm and said supply voltage V_dd.

17. A two-wire coupled control system according to claim 16, wherein said communications voltage V_comm is provided from a dc supply means which includes a thermostat transformer having a primary coupled to household ac power and a secondary providing low voltage ac power, and rectifier means coupled to said secondary.