CAN communication for building automation systems

• US 20060095146A1
• Filed: 12/16/2005
• Published: 05/04/2006
• Est. Priority Date: 03/05/2003
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Colorado vNet, LLC
• Inventors: Hesse, Scott, Kiwimagi, Gary, Ogawa, Craig, Files, Craig
• Granted Patent: US 7,433,740 B2
• Time in Patent Office: Days
• US Class Current: 700/19
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence
• CPC Class Codes: G05B 2219/25032 CAN, canbus, controller area network bus
• CPC Class Codes: G05B 2219/25211 Broadcast mode, length message, command, address of originator and destination

Abstract

Systems and methods for implementing CAN communication for building automation systems are disclosed. An exemplary system may comprise at least one sending device linked to a plurality of receiving devices over a CAN automation network. A control frame may be broadcast over the CAN automation network by the at least one sending device, the control frame encapsulated into a CAN extended data frame. An acceptance filter may be provided at each of the plurality of receiving devices, each of the plurality of receiving devices reading the control frame from the CAN extended data frame and determining if the receiving device is a target device based on the control frame. Device communication may also be implemented as methods for dynamic address assignment and firmware download.

Claims

1. A building automation system comprising:

at least one sending device linked to a plurality of receiving devices over a CAN automation network;

a control frame broadcast over the CAN automation network by the at least one sending device, the control frame encapsulated into a CAN extended data frame; and

an acceptance filter at each of the plurality of receiving devices, each of the plurality of receiving devices reading the control frame from the CAN extended data frame and determining if the receiving device is a target device based on the control frame.

2. The building automation system of claim 1 wherein the control frame includes a command packet for requesting the target device to execute an automation function.

3. The building automation system of claim 1 wherein the control frame includes a command packet for requesting status information from the target device.

4. The building automation system of claim 1 wherein the control frame includes an event packet indicating only that an action occurred at the sending device.

5. The building automation system of claim 1 wherein a single event identified in the event packet triggers action at a plurality of automation devices.

6. The building automation system of claim 1 wherein a single event identified in the event packet triggers action at a single automation device.

7. The building automation system of claim 1 further comprising a data frame broadcast over the CAN automation network by the at least one sending device, the data frame encapsulated into a CAN extended data frame for sending data between devices on the CAN automation network.

8. The building automation system of claim 7 wherein the control frame and data frame each include a destination field ID identifying an address of the target device.

9. The building automation system of claim 8 wherein the acceptance filter decodes the destination field ID to determine if the receiving device is the target device.

10. The building automation system of claim 7 wherein the control frame and data frame each include a source ID identifying an address of the sending device.

11. The building automation system of claim 10 wherein the target device returns data to the sending device using the source ID.

12. The building automation system of claim 10 wherein the target device returns either an ACK or NAK to the sending device using the source ID.

13. The building automation system of claim 1 wherein the control frame is issued as a priority message.

14. A method for assigning dynamic addresses to automation devices in a building automation system, comprising:

connecting an automation device to a CAN automation network in the building automation system;

broadcasting over the CAN automation network a unique identifier for the automation device;

receiving the unique identifier at a control module for the building automation system;

determining at the control module whether an address already exists for the automation device;

reassigning an existing dynamic address for the automation device to the automation device if a dynamic address already exists for the automation device;

assigning a new dynamic address to the automation device if an address does not already exist for the automation device; and

issuing an ID response packet from the control module with the address for the automation device.

15. The method of claim 14 wherein the address already exists if the automation device was taken offline, reset, or replaced.

16. The method of claim 14 wherein the address does not already exists if the automation device is new to the building automation system.

17. The method of claim 14 wherein the control module is a primary bridge on a CAN automation network subnet where the automation device is connected.

18. The method of claim 17 wherein the address includes subnet information for where the automation device is connected.

19. The method of claim 17 further comprising saving the address issued by the control module at the automation device only if a GUID in the ID response packet matches a GUID for the automation device.

20. The method of claim 17 further comprising executing a self-healing operations wherein a dynamic address for an original device is assigned to a replacement device for the original device if the original device is taken offline.

21. A method for updating program code for automation devices in a building automation system, comprising:

broadcasting over a CAN automation network a download request identifying a current version of program code at the automation device;

receiving the download request at a control module;

determining at the control module if a newer version of program code is available for the automation device;

returning an EOF packet to the automation device if a newer version of program code is not available for the automation device; and

initiating a transfer session over the CAN automation network with the automation device if a newer version of program code is available for the automation device.

22. The method of claim 21 wherein returning an EOF packet to the automation device restarts the automation device.

23. The method of claim 21 wherein broadcasting a download request by the automation device is only after the automation device is brought online in the building automation system.

24. The method of claim 21 further comprising issuing an ACK packet by the automation device after verifying at the automation device that at least a portion of the newer version of program code is received from the control module.

25. The method of claim 21 further comprising returning an EOF packet to the automation device after the transfer session is complete.