Supervised input converter

• US 20050030215A1
• Filed: 08/08/2003
• Published: 02/10/2005
• Est. Priority Date: 08/08/2003
• Status: Active Grant

• Current Assignee: Johnson Controls Tyco IP Holdings LLP (Johnson Controls International plc)
• Original Assignee: Sensormatic Electronics Corporation (Johnson Controls International plc)
• Inventors: Venditti, Robert A., Grigorov, Peter, Zaparovanny, Alexey Y.
• Granted Patent: US 7,154,425 B2
• Time in Patent Office: Days
• US Class Current: 341/155
• CPC Class Codes: G07C 9/00944 Details of construction or manufacture

Abstract

A multiplexer selects an input signal from one of plural sensors. An A/D converter converts the selected input signal to a digital input value. A processor then determines, based on the digital input value, an output resistance to which the resistance of the selected sensor is to be translated. Finally, the processor controls a digital potentiometer corresponding to the selected sensor to the determined output resistance. In one embodiment, a conditioning circuit adjusts the gain of the input signal according to calibration data, effectively performing at least a part of the translation in the analog domain.

Claims

1. A supervisory input converter, comprising:

a processor;

a multiplexer for selecting, under control of the processor, an input signal from one of plural sensors;

an analog-to-digital converter which converts the selected input signal to a digital input value, the processor then determining, based on the digital input value, an output resistance to which the resistance of the selected sensor is to be translated;

a digital potentiometer corresponding to the selected sensor, the processor controlling the digital potentiometer to the determined output resistance.

2. The supervisory input converter of claim 1, further comprising;

a conditioning circuit which adjusts gain of the input signal.

3. The supervisory input converter of claim 1, further comprising:

at least one lamp providing a status indication.

4. The supervisory input converter of claim 1, further comprising:

non-volatile memory which holds calibration data.

5. The supervisory input converter of claim 1, further comprising:

a serial interface.

6. A supervisory input converter, comprising:

an analog-to-digital converter which converts a supervisory input signal from a sensor to a first digital signal, the first digital signal being responsive to the sensor'"'"'s resistive state;

a translator which, responsive to the first digital signal, outputs a second digital signal;

a digital potentiometer which provides a resistance responsive to the second digital signal.

7. The supervisory input converter of claim 6, the translator comprising calibration data.

8. The supervisory input converter of claim 7, the calibration data being stored in a non-volatile memory.

9. The supervisory input converter of claim 6, the translator comprising:

a processor which translates the first digital signal to the second digital signal.

10. The supervisory input converter of claim 6, the translator comprising:

a conditioning circuit which adjusts gain of the supervisory input signal.

11. The supervisory input converter of claim 6, further comprising:

at least one lamp providing a status indication.

12. A method for converting an input resistance to an output resistance, comprising:

converting the input resistance to a digital input value; and

controlling a digital potentiometer to a desired output resistance responsive to the digital input value.

13. The method of claim 12, further comprising:

adjusting gain of a signal representing the input resistance prior to conversion.

14. The method of claim 12, further comprising:

indicating status with at least one lamp.

15. The method of claim 12, further comprising:

storing calibration data in non-volatile memory.

16. The method of claim 12, further comprising:

performing at least one of diagnostics, control, and calibration responsive to a message received over a serial interface.

17. A method for converting supervised input signals, comprising:

selecting from a plurality of supervised inputs, each supervised input having a corresponding input resistance indicative of said supervised input'"'"'s state;

converting the selected supervised input'"'"'s input resistance to a digital input value; and

controlling a digital potentiometer to a desired output resistance responsive to the digital input value.

18. The method of claim 17, comprising:

adjusting gain of a signal from the selected supervised input signal, said signal prior to adjustment being indicative of said supervised input'"'"'s resistance

19. An apparatus for converting an input resistance to an output resistance, comprising;

means for converting the input resistance to a digital input value; and

means for controlling a digital potentiometer to a desired output resistance responsive to the digital input value.

20. The apparatus of claim 19, further comprising:

means for adjusting gain, prior to conversion, of a signal representing the input resistance.

21. An apparatus for converting supervised input signals, comprising:

means for selecting from a plurality of supervised inputs, each supervised input having a corresponding input resistance indicative of said supervised input'"'"'s state;

means for converting the selected supervised input'"'"'s input resistance to a digital input value; and

means for controlling a digital potentiometer to a desired output resistance responsive to the digital input value.

22. The apparatus of claim 21, comprising:

means for adjusting gain of a signal from the selected supervised input signal, said signal prior to adjustment being indicative of said supervised input'"'"'s resistance.

23. A method for converting an input resistance to an output resistance, comprising:

adjusting gain of a signal representing the input resistance;

converting the input resistance to a digital input value; and

controlling a digital potentiometer to a desired output resistance responsive to the digital input value.

24. A method for converting an input resistance to an output resistance, comprising:

converting the input resistance to a digital input value;

controlling a digital potentiometer to a desired output resistance responsive to the digital input value; and

indicating status with at least one lamp.

25. A method for converting an input resistance to an output resistance, comprising:

converting the input resistance to a digital input value;

controlling a digital potentiometer to a desired output resistance responsive to the digital input value; and

storing calibration data in non-volatile memory.

26. A method for converting an input resistance to an output resistance, comprising:

converting the input resistance to a digital input value;

controlling a digital potentiometer to a desired output resistance responsive to the digital input value; and

performing at least one of diagnostics, control, and calibration responsive to a message received over a serial interface.

27. An apparatus for converting an input resistance to an output resistance, comprising:

means for adjusting gain of a signal representing the input resistance;

means for converting the input resistance to a digital input value; and

means for controlling a digital potentiometer to a desired output resistance responsive to the digital input value.