Method of transmitting a high-priority message in a lighting control system

• US 20080192767A1
• Filed: 02/08/2007
• Published: 08/14/2008
• Est. Priority Date: 02/08/2007
• Status: Active Grant

• Current Assignee: Lutron Technology Company LLC
• Original Assignee: Lutron Electronics Company Incorporated (Lutron Electronics)
• Inventors: Raneri, Daniel Curtis, Howe, William H., Abraham, Arya, Majewski, Timothy S., Stocker, R. Paul
• Granted Patent: US 7,787,485 B2
• Time in Patent Office: Days
• US Class Current: 370/449
• CPC Class Codes: H05B 47/18 via data-bus transmission

Abstract

A lighting control system having a plurality of control devices coupled to a communication link operates with a communication protocol that allows the system to expeditiously process high-priority events while operating communicate at a low enough baud rate to allow for a free-wiring topology of the communication link. The transmission of regular-priority messages is suspended if any of the control devices has a high-priority message to transmit. To signal that a control device has a high-priority message to transmit, each control device is operable to transmit a break character in a predetermined time period after the transmission of one of the digital messages. After the transmission of the break character, the transmission of the regular-priority messages on the communication link is suspended to allow the high-priority message to be transmitted quickly.

Claims

1. A method of transmitting a high-priority digital message via a communication link, the method comprising the steps of:

transmitting regular-priority digital messages between a plurality of control devices;

signaling that one of the plurality of control devices has a high-priority digital message to transmit;

suspending the transmission of the regular-priority digital messages between the plurality of control devices; and

transmitting the high-priority digital message during the suspension of the transmission of the regular-priority digital messages.

2. The method of claim 1, wherein the step of transmitting regular-priority digital messages between a plurality of control devices further comprises the steps of:

a first device transmitting a first message to a second device;

the second device transmitting to the first device a response to the first message.

3. The method of claim 2, wherein the step of signaling that one of the plurality of control devices has a high-priority digital message to transmit further comprises the step of:

the second device transmitting a break character in a predetermined time period following the first message.

4. The method of claim 3, wherein the step of transmitting the high-priority digital message during the suspension of the transmission of the regular-priority digital messages further comprises the steps of:

the first device transmitting a second message to the second device in response to receiving the break character; and

the second device transmitting the high-priority digital message in response to the second message.

5. The method of claim 4, wherein the step of suspending the transmission of the regular-priority digital messages between the plurality of control devices further comprises the step of:

the first device determining a Poll ID of the second device in response to the second device transmitting the break character.

6. The method of claim 5, wherein the step of the first device determining a Poll ID of the second device further comprises the first device executing a binary search of the plurality of control devices.

7. The method of claim 6, further comprising the steps of:

ending the suspension of the transmission of the regular-priority digital messages; and

transmitting regular-priority digital messages between the plurality of control devices after the step of ending the suspension of the transmission of the regular-priority digital messages.

8. The method of claim 7, further comprising the steps of:

the second device transmitting the high-priority digital message only once during the suspension of the transmission of the regular-priority digital messages.

9. The method of claim 8, wherein the step of the second device transmitting the high-priority digital message only once during the suspension of the transmission of the regular-priority digital messages further comprises the steps of:

the second device setting an HPR_LOCK flag in response to the step of the second device transmitting the high-priority digital message;

the second device determining whether the HPR_LOCK flag is set prior to the step of the second device transmitting the high-priority digital message; and

the second device clearing the HPR_LOCK flag in response to the step of transmitting regular-priority digital messages between the plurality of control devices after the step of ending the suspension of the transmission of the regular-priority digital messages.

10. The method of claim 7, wherein the step of signaling that one of the plurality of control devices has a high-priority digital message to transmit further comprises a subset of the plurality of control devices transmitting a break character in the predetermined time period following the first message;

and

the step of executing a binary search further comprises repeatedly executing the binary search to determine each of the subset of control devices that transmitted the break character.

11. The method of claim 3, wherein the step of the second device transmitting a break character in a predetermined time period following the first message further comprises the second device asserting the communication link for an amount of time during the predetermined time period.

12. The method of claim 1, wherein the step of transmitting regular-priority digital messages between a plurality of control devices further comprises the step of:

each of the plurality of control devices beginning to transmit a regular-priority digital message during a unique predetermined time slot.

13. The method of claim 12, wherein the step of signaling that one of the plurality of control devices has a high-priority digital message to transmit further comprises the step of:

a first device transmitting a break character in a predetermined time period following one of the regular-priority digital messages.

14. The method of claim 13, wherein the step of suspending the transmission of the regular-priority digital messages between the plurality of control devices further comprises the steps of:

preventing each of the plurality of control devices from beginning to transmit the regular-priority digital message during the unique predetermined time slot in response to the first device transmitting the break character; and

allowing each of the plurality of control devices to begin transmitting the high-priority digital messages during the unique predetermined time slot during the suspension of the transmission of the regular-priority digital messages.

15. The method of claim 14, wherein the step of suspending the transmission of the regular-priority digital messages between the plurality of control devices further comprises preventing each of the plurality of control devices from beginning to transmit the regular-priority digital messages during the unique predetermined time slot for one timing cycle.

16. The method of claim 1, further comprising the step of:

actuating a button on the one of the plurality of control devices prior to the step of signaling that one of the plurality of control devices has a high-priority digital message to transmit.

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

a second one of the plurality of control devices receiving the high-priority digital message; and

the second one of the plurality of control devices controlling the intensity of a lighting load in response to the high-priority message.

18. A method of transmitting a high-priority digital message between a plurality of control devices via a communication link, the method comprising the steps of:

operating the communication link in a normal mode of operation by transmitting regular-priority digital messages between the plurality of control devices;

signaling that one of the plurality of control devices has a high-priority digital message to transmit;

changing the communication link to a high-priority mode of operation in response to the step of signaling, the transmission of regular-priority digital messages suspended in the high-priority mode of operation; and

transmitting the high-priority digital message while the communication link is in the high-priority mode of operation.

19. A method of transmitting a high-priority digital message from a second control device to a first control device, the method comprising the steps of:

the first device transmitting a first message;

the second device transmitting a high-priority break character during a predetermined time period following the first device transmitting the first message;

the first device transmitting a second message to the second device in response to receiving the high-priority break character; and

the second device transmitting the high-priority digital message to the first device in response to the second message.

20. The method of claim 19, wherein the second device includes a Poll ID selected from a plurality of Poll IDs, the method further comprising the step of:

the first device determining the Poll ID of the second device in response to the second device transmitting the high-priority break character, prior to the step of the first device transmitting a second message to the second device.

21. The method of claim 20, wherein the step of the first device determining a Poll ID of the second device comprises the first device executing a binary search routine.

22. The method of claim 21, wherein the step of the first device executing a binary search routine further comprises the steps of:

the first device transmitting an HPR-search poll message including a search range of Poll IDs;

the second device determining whether the Poll ID of the second device is within the search range of Poll IDs; and

the second device transmitting a search break character in a predetermined time period following the first device transmitting the HPR-search poll message when the Poll ID of the second device is within the search range of Poll IDs.

23. A method of polling a plurality of control devices on a communication link, each of the plurality of control devices having a unique Poll ID, the method comprising the steps of:

sequentially transmitting a poll message to each of the plurality of control devices using the Poll ID of each control device;

transmitting a break character in a predetermined time period following one of the poll messages;

suspending the sequential transmission of poll messages in response to the step of transmitting a break character;

determining which one of the plurality of control devices transmitted the break character;

transmitting a request message to the one of the plurality of control devices that transmitted the break character; and

transmitting from the one of the plurality of control devices that transmitted the break character a high-priority digital message in response to the request message.

24. The method of claim 23, wherein the step of transmitting a break character comprises more than one of the plurality of control devices simultaneously transmitting a break character in the predetermined time period following one of the poll messages.

25. A method of polling a plurality of control devices by a master device selected from said plurality of control devices, the plurality of control devices each coupled to a communication link and including a unique Poll ID, the method comprising the steps of:

the master device sequentially transmitting a poll message to each control device marked active in a list of Poll IDs, the poll message including a status request;

each of the control devices responding to the poll message when the Poll ID of the device matches the Poll ID of the poll message;

one of the control devices transmitting a high-priority request;

the master device interrupting the sequential transmission of poll messages when the high-priority request is received; and

performing a binary search to find the Poll ID of the control device that provided the high-priority request.

26. A method of transmitting a high-priority digital message from a second control device to a first control device, the first and second control devices operable to transmit regular-priority digital messages, the method comprising the steps of:

the first device beginning to transmit a regular-priority digital message during a first predetermined time slot;

the second device transmitting a break character during a predetermined time period following the end of the regular-priority message;

the first device suspending the transmission of regular-priority digital messages in response to receiving the break character; and

the second device beginning to transmit the high-priority digital message during a second predetermined time slot while the first device has suspended the transmission of regular-priority digital messages.

27. A control device for a lighting control system having a communication link, the control device comprising:

a communication circuit operable to be coupled to the communication link for transmission and receipt of digital messages;

a controller coupled to the communication circuit and operable to control the transmission and receipt of the digital messages; and

an input coupled to the controller;

wherein the controller is operable to transmit a first message having a regular-priority, the controller further operable to transmit a second message having a high-priority in response to the input.

28. The control device of claim 27, wherein the input comprises an actuator operable to be actuated by a user.