BACnet Communication Status Objects and Methods of Determining Communication Status of BACnet Devices

• US 20090287736A1
• Filed: 06/04/2008
• Published: 11/19/2009
• Est. Priority Date: 05/16/2008
• Status: Active Grant

• Current Assignee: Schneider Electric Buildings AB (Schneider Electric SE)
• Original Assignee: Tac, LLC (Schneider Electric SE)
• Inventors: Wilson, Mike, Koch, Rick, Shike, David
• Granted Patent: US 7,761,563 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 12/417 with deterministic access, e.g. token passing
• CPC Class Codes: H04L 43/0811 by checking connectivity

Abstract

BACnet objects and methods for efficiently monitoring the communication status of networks and devices in a building automation and control system are presented. A pair of bus communication status objects, including a server object and a client object, provide the communication status of an MS/TP network as an OCTET String transmitted only upon a change of value (COV) of the communication status of a device on the network. Individual devices may be monitored with a device communication status object, in conjunction with or apart from the bus communication status objects. For MS/TP devices, automatic configuration and monitoring in a controller is provided. For other devices, a user interface is provided through a graphical tool to allow configuration to specify the desired device and/or network for monitoring.

Claims

1. A method of determining a communication status of at least one BACnet device, comprising the steps of:

monitoring communication of the at least one BACnet device on a local network bus;

generating by a bus communication status server object an octet string containing information reflecting the communication status of the at least one BACnet device;

transmitting the octet string upon a change of value (COV) of the octet string indicating a change in the communication status of at least one of the at least one BACnet device;

receiving by a bus communication status client object the octet string;

deciphering the octet string to determine the communication status of each of the at least one BACnet devices; and

providing the communication status of each of the at least one BACnet devices to at least one corresponding device communication status object.

2. The method of claim 1, wherein the local network bus is a BACnet MS/TP communications bus, and wherein the step of monitoring communications comprises the step of monitoring token passing on the BACnet MS/TP communications bus.

3. The method of claim 1, further comprising the steps of:

transmitting by the bus communication status client object a Who-Has service request identifying the local network bus;

receiving by the bus communication status client object an I-Have service response identifying the bus communication status server object for the local network bus; and

transmitting by the bus communication status client object a SubscribeCOV service request to the bus communication status server object.

4. The method of claim 1, further comprising the steps of creating the device communication status object for each of the at least one BACnet device.

5. A computer readable medium having instructions for causing a computer to execute a method comprising the steps of:

monitoring communication of the at least one BACnet device on a local network bus;

generating by a bus communication status server object an octet string containing information reflecting the communication status of the at least one BACnet device;

transmitting the octet string upon a change of value (COV) of the octet string indicating a change in the communication status of at least one of the at least one BACnet device;

receiving by a bus communication status client object the octet string;

deciphering the octet string to determine the communication status of each of the at least one BACnet devices; and

providing the communication status of each of the at least one BACnet devices to at least one corresponding device communication status object.

6. A memory for storing data for access in a BACnet building automation and control system by an application program being executed on a data processing system, comprising:

a data structure stored in the memory, the data structure including information used by the application program for representing the bus communication status of a BACnet bus and including;

an object identifier property field containing data representing BACnet object and object instance number;

an object name field containing data representing a human readable character string describing the object;

an object type field containing data representing a type of BACnet object; and

a present value field containing an octet string representing communication status of devices on the BACnet bus.

7. The memory of claim 6, wherein the object type field contains a value identifying the BACnet object as a MS/TP Bus Communications Status Server Object.

8. The memory of claim 7, wherein the value is 512.

9. The memory of claim 6, wherein the object type field contains a value identifying the BACnet object as a MS/TP Bus Communications Status Client Object.

10. The memory of claim 9, wherein the value is 513.

11. A memory for storing data for access in a BACnet building automation and control system by an application program being executed on a data processing system, comprising:

a data structure stored in the memory, the data structure including information used by the application program for representing the device communication status of a BACnet device and including;

an object identifier property field containing data representing BACnet object and object instance number;

an object name field containing data representing a human readable character string describing the object;

an object type field containing data representing a type of BACnet object; and

a monitored device address field containing an octet string representing a MAC address of the BACnet device to be monitored by this object.

12. The memory of claim 11, wherein the data structure further comprises a monitored device BACnet network number field containing data representing a BACnet network number of the BACnet device to be monitored.

13. The memory of claim 12, wherein the monitored device BACnet network number field contains a 0 when the BACnet device to be monitored is locally connected to MS/TP port 0.

14. The memory of claim 11, wherein the data structure further comprises a monitored device address type field containing data representing an enumeration value for MS/TP, Ethernet, BACnet/IP, Device ID and Scan mode.

15. A BACnet building automation and control system, comprising:

a subnet controller operatively coupled via a BACnet MS/TP communication bus to at least one BACnet device to form a subnet, the subnet controller including a BACnet communication status process for monitoring the communication status of the at least one BACnet device, the subnet controller exposing a bus communication status server object operative to broadcast information regarding communication status of all of the BACnet devices on the subnet as monitored by the communication status process when a change of value of the communication status occurs;

a remotely located BACnet controller in operative communication with the subnet controller, the BACnet controller exposing a bus communication status client object, and wherein the bus communication status client object subscribes to change of value broadcasts of the bus communication status server object to determine the communication status of all of the BACnet devices on the subnet.

16. The system of claim 15, wherein the BACnet controller further exposes at least one device communication status object, the at least one device communication status object corresponding to the at least one BACnet device on the subnet, and wherein the device communication status object outputs the communication status of its corresponding BACnet device as determined by the bus communication status client object from the information broadcast from the bus communication server object.

17. The system of claim 15, wherein the bus communication status client object locates the bus communication status server object by broadcasting a Who-Has request that specifies a subnet number of interest, and wherein the bus communication status server object broadcasts an I-Have message in response to the Who-Has request when the subnet number matches the subnet controller'"'"'s subnet number.

18. The system of claim 17, wherein the bus communication status client object transmits a SubscribeCOV message to the bus communication status server object, and thereafter wherein the bus communication status server object transmits a ConfirmedCOVNotification message to the bus communication status client object when any change in communication status on the subnet.

19. The system of claim 15, wherein the information is in the form of an Octet String.

20. A user interface commissioning a device communication status object for a BACnet building automation and control system having at least one BACnet device whose communication status is of interest, comprising:

a window having a first and a second portion contained therein;

a list of available types of device communication status object to be commissioned positioned in the first portion of the window and capable of responding to user input for identifying the type of device communication status object to be commissioned; and

a device specifier positioned in the second portion of the window and capable of receiving user input for identifying the BACnet device whose communication status is of interest, and wherein information required to be entered by a user varies as selection of the type of device communication status object to be commissioned varies.

21. The user interface of claim 20, wherein the list includes at least a network type selection, and wherein the device specifier requires a network number be input by a user.

22. The user interface of claim 20, wherein the list includes at least a device ID type selection, and wherein the device specifier requires a device instance number be input by a user.

23. The user interface of claim 20, wherein the list includes at least a BACnet/IP type selection, and wherein the device specifier requires a network number, an IP address, and an IP Port be input by a user.

24. The user interface of claim 20, wherein the list includes at least an Ethernet type selection, and wherein the device specifier requires a network number and an Ethernet MAC address be input by a user.

25. The user interface of claim 20, wherein the list includes at least an MS/TP type selection, and wherein the device specifier requires a network number and an MS/TP address be input by a user.