On-line monitoring of controllers in an environment control network

• US 5,682,329 A
• Filed: 12/20/1994
• Issued: 10/28/1997
• Est. Priority Date: 07/22/1994
• Status: Expired due to Term

• Current Assignee: BBNT Solutions LLC (Rtx Corporation)
• Original Assignee: Johnson Service Company
• Inventors: Seem, John, Monroe, Richard H., Jensen, Howard A.
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): SHAH, KAMINI S
• Application Number:
  US08/360,217
• Time in Patent Office: 1,043 Days
• Field of Search: 340/679, 364/184, 364/508, 364/581, 364/582, 364/575, 364/510, 364/551.01, 236/49.5, 236/45, 236/25 R, 62/93, 62/126, 62/129, 62/16, 105/16
• US Class Current: 700/276
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/38 Failure diagnosis
• CPC Class Codes: F24F 11/52 Indication arrangements, e.g. displays
• CPC Class Codes: F24F 11/54 using one central controller connected to several sub-controllers
• CPC Class Codes: F24F 11/63 Electronic processing
• CPC Class Codes: F24F 3/044 Systems in which all treatment is given in the central station, i.e. all-air systems
• CPC Class Codes: G01F 1/34 by measuring pressure or differential pressure
• CPC Class Codes: G01F 15/063 using electrical means
• CPC Class Codes: G05B 19/4184 characterised by fault tolerance, reliability of production system

Abstract

The present invention relates to a diagnostic system for use in a network control system. The diagnostic system is preferably utilized to analyze HVAC system or VAV box performance in an environmental control system such as a network facilities management system. The diagnostic system advantageously records temperature, air flow, and actuator position data in the controller associated with the VAV box and calculates an exponentially weighted moving average value. The exponentially weighted moving average value may be related to error values, process output values, change in actuator position, actuator position, duty cycle of the actuator, or starts, stops and reversals of the actuator. Such a system allows a person to analyze VAV boxes and controller performance over a particular timely period and the lifetime of the system. Box and damper warnings may be provided by the diagnostic system when the EWMA values are over or under particular threshold values. The EWMA values are advantageously calculated and stored in the individual controllers.

Claims

1. In an environment control network, the network including a computer, and a plurality of units for controlling a process, each of said units including an appliance for controlling a portion of said process, each of said plurality of units operatively associated with a controller, each of said controllers comprising:

an appliance output coupled to said appliance, said appliance output providing an appliance signal for controlling said appliance;

a communication port;

a memory;

a processor coupled with said memory, said appliance output, and said communication port, said processor cyclically providing said appliance signal to control said appliance, said processor programmed to calculate and store weighted average data in said memory related to said appliance signal, wherein the computer is coupled to the communication port and the processor provides the weighted average data to said computer via the communication port in response to a summary command from said computer.

2. The controller of claim 1 further comprising a parameter input coupled with said processor, said processor programmed to receive a parameter value at said parameter input from an environment or other sensor, generate and store an exponentially weighted moving average parameter data related to said parameter value.

3. The controller of claim 2 wherein said parameter value is a humidity value, pressure value, temperature value or an air flow value.

4. The controller of claim 1 wherein said average data includes a duty cycle value of said appliance.

5. The controller of claim 2 wherein said parameter value is further comprised of a temperature value and an air flow value.

6. The controller of claim 1 wherein said communication port is coupled to the computer via a communication bus.

7. In a control network including a plurality of individual controllers, the controllers being coupled together on a communication link, the communication link being coupled to a computer, the controllers cooperating to control a process, a method of generating a performance index for monitoring performance of the controllers, the method comprising steps of:

periodically sampling a parameter related to said process with each of said plurality of controllers, wherein said parameter is received from a sensor;

generating a new time weight average of said parameter in accordance with said parameter and a stored time weight average of said parameter, said stored time weight average being a function of the previous values of said parameter, said new time weight average being said performance index;

storing said new time weight average of said parameter as said stored time weight average; and

transmitting the stored time weight average to the computer in response to a command from the computer.

8. The method of claim 7, wherein said parameter is related to a parameter error, the parameter error is a different of a parameter setpoint value and an actual parameter value.

9. The method of claim 7, wherein said parameter value is related to air flow or temperature.

10. The method of claim 8, wherein said parameter value is comprised of a value related to temperature and a value related to said air flow.

11. The method of claim 7, wherein the new time weight average is stored in the controllers, and further comprising a step of providing the new time weight average to said communication link.

12. The method of claim 7, wherein said parameter value is related to an output signal from the controllers.

13. In an environment control network including a computer, and a plurality of units, each of said units providing air flow to an environment, each of said plurality of units operatively associated with a controller, each of said controllers being operatively coupled to said computer via a communication bus, each said controller comprising:

an environment sensor for providing a parameter value related to said environment;

a communication port coupled to the computer;

a memory; and

a processor coupled with said memory and said environment sensor, said processor programmed to receive said parameter value from said environment sensor, generate an exponentially weighted moving average index related to said parameter value, and store said index in said memory, wherein a processor provides said exponentially weighted moving average index to said computer via said communication port.

14. The controller of claim 13 wherein said parameter value is related to temperature or air flow.

15. A VAV controller operatively associated with a VAV box, said VAV controller coupled to a first communication bus, said VAV controller comprising:

parameter input means for receiving a parameter value from a sensor;

a communication port coupled with said first communication bus;

memory means for storing diagnostic information; and

processor means coupled with said memory means, said parameter input means, and said communication port, for generating said diagnostic information and receiving said parameter value, and said processor means programmed to receive said parameter value at said parameter input, said processor means programmed to generate said diagnostic information, said diagnostic information being related to an exponentially weighted moving average error associated with said parameter value, said processor means programmed to provide said diagnostic information to said communication port, wherein a computer is responsive to the diagnostic information provided to said communication port via said first communication bus.

17. The VAV controller of claim 15 wherein the computer is a work station.

18. The VAV controller of claim 15 wherein said diagnostic information includes moving average temperature error data.

20. The VAV controller of claim 15 wherein said controller provides an actuator signal to said VAV box for controlling air flow, and wherein said diagnostic information further is comprised of a plurality of samples of said actuator signal.

16. A VAV controller operatively associated with a VAV box, said VAV controller coupled to a first communication bus, said VAV controller for use in a system including a station coupled with said first communication bus, a second communication bus coupled with said station and a portable computer couplable to said second communication bus, said VAV controller comprising:

parameter input means for receiving a parameter value from a sensor;

a communication port coupled with said first communication bus;

memory means for storing diagnostic information; and

processor means coupled with said memory means, said parameter input means, and said communication port, for generating said diagnostic information and receiving said parameter value, and said processor means receiving said parameter value at said parameter input, said processor means programmed to generate said diagnostic information, said diagnostic information being related to an exponentially weighted moving average error associated with said parameter value, said processor means providing said diagnostic information to said communication port, said communication port providing said diagnostic information to said first communication bus, said first communication bus providing the diagnostic information to said station, said station providing the diagnostic information to said second communication bus, said portable computer receiving said diagnostic information from said second communication bus.

19. The VAV controller of claim 16 wherein said portable computer is programmed to display said diagnostic information.