Supervisory control system for microprocessor based appliance controls

• US 4,611,295 A
• Filed: 06/28/1985
• Issued: 09/09/1986
• Est. Priority Date: 05/28/1982
• Status: Expired due to Term

• Current Assignee: Robertshaw Controls Company (Schneider Electric SE)
• Original Assignee: Robertshaw Controls Company (Schneider Electric SE)
• Inventors: Fowler, Daniel L.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/750,066
• Time in Patent Office: 438 Days
• Field of Search: 364/138, 364/140, 364/141, 364/184, 364/186, 371/15, 371/20, 371/24, 371/62, 307/38, 307/85, 307/86, 307/132 E, 307/141, 307/141.4, 307/234, 307/442, 307/518, 361/78, 361/83, 340/506, 340/507, 340/812, 340/825.16
• US Class Current: 700/79
• CPC Class Codes: G05B 19/0428 Safety, monitoring G05B19/0423 takes precedence
• CPC Class Codes: G05B 2219/21163 Test I-O if functional or safe value
• CPC Class Codes: G05B 2219/24125 Watchdog, check at timed intervals
• CPC Class Codes: G06F 11/0736 in functional embedded systems, i.e. in a data processing system designed as a combination of hardware and software dedicated to performing a certain function testing or monitoring of automated control systems G05B23/02
• CPC Class Codes: G06F 11/0751 Error or fault detection not based on redundancy power supply failures G06F1/30; network fault management H04L41/06
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: H05B 6/666 Safety circuits emergency protective circuits in general H02H

Abstract

A supervisory control system for microprocessor based appliance controls, the supervisory control system incorporating means for detecting dynamic failure of a microprocessor incorporated in the appliance control, means for disabling the high energy circuits in the associated appliance if the microprocessor is not operating in a normal mode and switch means requiring a physical or mechanical operation to enable energization of the high energy circuits of the associated appliance whereby the high energy circuits of the associated appliance are disabled unless at least two predetermined criteria are met.

Claims

1. A power relay for operating an appliance in combination with a supervisory control system for providing control, supervision and safety shutdown of the output of said power relay, said supervisory control system comprising in combination:

a. a microprocessor including an input terminal and a pair of output terminals conditioned to generate control signals at said output terminals upon receipt of a signal at said input terminal;

b. manually or force actuated start switch means connected to a source of potential and to said input terminal;

c. electronic latch and missing pulse detector means including a comparator connected to both said switch means and one of said output terminals;

d. inhibit means connected to said electronic latch and missing pulse detector means and controlling energization of said power relay; and

e. relay driver means connected to said power relay and the other of said output terminals to control energization of said power relay;

wherein when said switch means is closed, control signals emitted from said microprocessor are AC coupled through said electronic latch and missing pulse detector means, said inhibit means, and said relay driver means to control the output of said power relay.

2. The combination as set forth in claim 1 including band pass filter means connected between said electronic latch and missing pulse detector means and said one output terminal.

3. The combination as set forth in claim 1, said switch means requiring the application of physical force thereto to effect closure thereof.

4. The combination as set forth in claim 1, said electronic latch and missing pulse detector means including voltage divider means connected to said comparator.

5. The combination as set forth in claim 1 including an RC network connected to said comparator.

6. The combination as set forth in claim 1, said inhibit means including a first transistor connected to the output of said comparator and a second transistor controlled by said first transistor and connected to said relay driver means.

7. The combination as set forth in claim 1, said relay driver means including solid state means connected between said other output terminal of said microprocessor and said power relay means.

8. The combination as set forth in claim 7 including snubber diode means connected between said power relay means and ground.

9. A power relay for operating an appliance in combination with a supervisory control system for providing control, supervision and safety shutdown of the output of said power relay, said supervisory control system comprising in combination:

a. a microprocessor including an input terminal, a pair of output terminals, and a pulsed ground source;

b. manually actuatable switch means connected between said pulsed ground source and said input terminal;

c. a band pass filter circuit connected to one of said output terminals;

d. an electronic latch and missing pulse detector circuit including a comparator connected to both said switch means and said band pass filter circuit;

e. inhibit means connected to said electronic latch and missing pulse detector circuit and said power relay; and

f. a relay driver circuit connected to said power relay and the other output terminal of said microprocessor, with said microprocessor being conditioned so that control signals are generated at said output terminals upon receipt of a signal at said input terminal from said pulsed ground source when said switch means is closed, said control signals being AC coupled through said band pass filter circuit, said electronic latch and missing pulse detector circuit, said inhibit means, said relay driver circuit to provide control, supervision and safety shutdown of the output of said power relay.

10. The combination as set forth in claim 9, said electronic latch and missing pulse detector circuit including voltage divider means connected between said comparator and said band pass filter circuit.

11. The combination as set forth in claim 10 including as RC network comprising a capacitor and a resistor connected to said comparator.

12. The combination as set forth in claim 11, said inhibit circuit including a first transistor connected to the output of said comparator and a second transistor controlled by said first transistor and connected to said relay driver circuit.

13. The combination as set forth in claim 12, said relay driver circuit including solid state means connected between said other output terminal of said microprocessor and said output relay.

14. The combination as set forth in claim 13 including a snubber diode connected between said power relay and ground.

15. A power relay for operating an appliance in combination with a supervisory control system for providing control, supervision and safety shutdown of the output of said power relay, said supervisory control system comprising in combination:

a. a microprocessor including an input terminal, a pair of output terminals, and a pulsed ground source;

b. a negative DC power supply;

c. a manually actuatable switch connected between said pulsed ground source and said input terminal;

d. a band pass filter circuit connected to said power supply and to one of said output terminals;

e. an electronic latch and missing pulse detector circuit including a comparator having a negative terminal, a positive terminal, and an output with said positive terminal being connected to said switch;

f. an RC network comprising a capacitor and a resistor connected to said positive terminal of said comparator;

g. inhibit means connected to said output of said comparator and said power relay; and

h. a relay driver circuit including solid state means connected to said power relay and the other output terminal of said microprocessor;

wherein said microprocessor conditioned to generate control signals at said output terminals upon receipt of a pulsed ground signal at said input terminal and said pulsed ground source when said switch is closed, said control signals generated at said output terminals being AC coupled through said band pass filter circuit, said electronic latch and missing pulse detector circuit, said RC network, said inhibit means, and said relay driver circuit to provide control, supervision, and safety shutdown of the output of said power relay.

16. The combination as set forth in claim 15, said inhibit circuit including a first transistor connected to said output of said comparator and a second transistor controlled by said first transistor and connected to said solid state means in said relay driver circuit.

17. The combination as set forth in claim 16 including a snubber diode connected between said power relay and ground.

18. The combination as set forth in claim 17 including a capacitor coupling said band pass filter circuit to said one output terminal of said microprocessor.