METHOD AND APPARATUS FOR REPEATING ILLUMINATION INFORMATION ON A DAISY CHAIN BUS STRUCTURE

• US 20110103401A1
• Filed: 03/12/2009
• Published: 05/05/2011
• Est. Priority Date: 03/13/2008
• Status: Active Grant

• Current Assignee: eldoLAB Holding B.V. (Acuity Brands, Inc.)
• Original Assignee: Eldolab Holdings BV
• Inventors: Welten, Petrus Johannes Maria
• Granted Patent: US 8,791,646 B2
• Time in Patent Office: Days
• US Class Current: 370/474
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling

Abstract

A data communication method is described for transmitting a data packet comprising data bytes in a daisy chained bus structure of a LED illumination system. The method comprises: the nodes of a group, except the last node of the group retransmitting the data packet without removing a first data byte from the incoming data packet; and the last node in the group removing the first byte from the data packet before retransmission. The invention further comprises a communication node, illumination assembly and bus structure implementing the method according to the invention.

Claims

1. A data communication method for transmitting a data packet comprising data bytes in a daisy chained bus structure of a LED illumination system, the method comprising:

the nodes of a group, except the last node of the group retransmitting the data packet without removing a first data byte from the incoming data packet; and

the last node in the group removing the first byte from the data packet before retransmission.

2. The data communication method according to claim 1, wherein the behavior to retransmit the data packet without removing a first byte from the incoming data packet is a fixed behavior of the node.

3. The data communication method according to claim 1, comprising commanding the nodes of the group to switch between the behavior to retransmit the data packet without removing the first data byte from the incoming data packet and the behavior to remove the first byte from the data packet before retransmission.

4. The data communication method according to claim 3, wherein the commanding comprises setting a start code at a beginning of a data packet to a certain value to instruct the nodes to interpret the data in the packet as configuration data.

5. The data communication method according to claim 1, further comprising storing data representing a behavior of the or each node in an information storage element of the node.

6. The data communication method according to claim 5, wherein at least one node interrogates a neighboring downstream node thereof for its type and deduces its behavior there from.

7. The data communication method according to claim 5, comprising transferring information from a tail of the chain towards a master of the chain, so that the master is provided with information representing a configuration of the nodes of the chain.

8. The data communication method according to claim 5, further comprising:

the master of the chain interrogating the first node after it'"'"'s type,

the master putting the first node in a transparent mode,

the master interrogating successive further nodes after their type and successively putting them in transparent mode,

the master sending an escape command to return all nodes to their operational state.

9. The data communication method according to claim 1, wherein a counter data is provided with the packet data, each node reducing a value of the counter data by a given amount and transmitting the data packet with the reduced counter value to a following node, until an end value of the counter is reached, the nodes that reduce the value of the counter data retransmitting the data packet without removing a first byte from the incoming data packet

10. The data communication method according to claim 1, wherein the bus structure comprises a DMX bus structure.

11. The data communication method according to claim 1, wherein the data packet is modified by a node of the group by adding data or replacing data, the modified data packet being transmitted to the following node of the group.

12. The data communication method according to claim 11, wherein a configuration data byte is added to the data packet to inform following nodes of the group that at least one data byte following the configuration data byte is to be interpreted in another way then standard.

13. The data communication method according claim 11, wherein a value of a data byte is changed by a node of the group into another value, before retransmission.

14. A communication node for a DMX communication network, the node comprising an input for receiving a data packet comprising data bytes and an output for retransmitting the data packet to a following node, wherein the data packet is retransmitted without removal of a first data byte of the incoming data packet.

15. An illumination fixture comprising a LED illumination source, a driver for driving the LED illumination source, and a node according to claim 14 to control the driver.

16. A bus structure comprising a plurality of nodes, each node comprising an input for receiving a data packet comprising data bytes and an output for retransmitting the data packet to a following node, wherein individual nodes are arranged for removing a first data byte from the data packet before retransmission, while a plurality of nodes forming a group, the nodes in the group, except the last one, exhibiting a different behavior than the individual nodes in that they are arranged for retransmitting the incoming data packet without removal of the first data byte from the data packet.