Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/10—Controlling the light source
  • H05B47/175—Controlling the light source by remote control
  • H05B47/18—Controlling the light source by remote control via data-bus transmission

Definitions

• the present invention relates to a method of detecting Short Address conflicts in a DALI (Digital Addressable Lighting Interface) system.
• DALI Digital Addressable Lighting Interface
• DALI Data Security
• IEC 62386-102 The basic operation of DALI systems is outlined in the DALI standard IEC 62386-102 which provides amongst other things an algorithm for Device Discovery and Short Address allocation. Whilst this algorithm provides a means of dealing with Short Address conflicts it does not provide details on how to detect such conflicts.
• a DALI bus provides a 64 device Short Address space and as with most bus systems, devices are required to have a unique Short Address for the system to operate properly. It is not uncommon for two devices on a DALI bus to inadvertently end up with the same Short Address. This can happen for instance, when a device with a first Short Address on a bus is replaced with a device configured with a second Short Address which is already in use by another device on the bus. This may happen when a faulty device on a bus is replaced or a new device added. The conflict may or may not be readily noticed.
• Another method for detecting Short Address conflicts is to query devices in such a way as to elicit a unique response from each device. This could be done for instance by querying the serial number (using the READ MEMORY LOCATION command) or reading the random address of each device (using the QUERY RANDOM ADDRESS command). When devices at the same Short Address respond with differing data they will produce a framing error, even when perfectly synchronized with each other.
• this method also has limitations: it relies on the devices being unique (which is often not the case, as some manufacturers produce devices with identical serial numbers); some devices may detect the conflict themselves and back-off from replying thus avoiding a framing error and remain unseen; not all devices are fully DALI compliant and may not implement all the commands used; and, the method is also susceptible to false positives when framing errors occur for some other reason. Also, this method will not work at all for multi-channel DALI devices as only one device of a multi-channel device may communicate with a DALI network at any particular time and therefore a framing error cannot be generated.
• Short Address conflicts In place of detecting Short Address conflicts at specific Short Addresses, if a Short Address conflict is suspected, or to just make sure that there are no conflicts a DALI system could simply have the Device Discovery and Short Address allocation algorithm repeated. This however is undesirable as it may change the Short Addresses of devices not in conflict which may necessitate further configuration actions.
• a method for detecting the presence of more than one device at a Short Address SA on a DALI bus, wherein the binary random number BRN of the devices is used to distinguish between the devices.
• Preferred embodiments comprise the steps of: issuing an INITIALISE command with the Short Address SA so that only devices with the Short Address SA will respond; issuing SEARCHADDRH, SEARCHADDRM and SEARCHADDRL commands to set the DALI search address to its maximum; issuing a first COMPARE command to find if any devices are present, and if present, then; repeatedly reducing the DALI search address and issuing COMPARE commands to find the device with the lowest BRN; issuing a WITHDRAW command to remove the device with the lowest BRN from consideration; setting the DALI search address to its maximum value; issuing a further COMPARE command to detect whether any further devices are present, the presence of the further devices being determined by observing a response to the further COMPARE command.
• a RANDOMISE command may be issued after the INITIALISE command so that the devices each choose a new binary random number, BRN.
• a TERMINATE command is issued before the INITIALISE command to cancel any previous INITIALISE commands.
• the steps of: repeatedly reducing the DALI search address and issuing COMPARE commands to find the device with the lowest BRN; issuing a WITHDRAW command; setting the DALI search address to its maximum; and issuing a further COMPARE command, may be repeated to detect the presence of all further devices.
• a method for detecting all Short Address conflicts on a DALI bus comprising repeating for each Short Address SA occupied on the DALI bus: issuing an INITIALISE command with the Short Address SA so that only devices with the Short Address SA will respond; setting the DALI search address to its maximum value; issuing a first COMPARE command to find if any devices are present and if present, then; repeatedly reducing the DALI search address and issuing COMPARE commands to find the device with the lowest BRN; issuing a WITHDRAW command to remove the device with the lowest BRN from consideration; setting the DALI search address to its maximum value; issuing a further COMPARE command to detect whether any further devices are present, the presence of the further devices being determined by observing a response to the further COMPARE command.
• Each Short Address SA occupied can be determined by sending a QUERY CONTROL GEAR SA command in turn for each DALI Short Address in the DALI Short Address space and reckoning that a Short Address is occupied if a DALI Yes is received or a framing error occurs.
• a method for detecting all Short Address conflicts on a DALI bus comprising repeating for each Short Address SA occupied with no conflict detected on the DALI bus: issuing an INITIALISE command with the Short Address SA so that only devices with the Short Address SA will respond; setting the DALI search address to its maximum value; issuing a first COMPARE command to find if any devices are present and if present, then ; repeatedly reducing the DALI search address and issuing COMPARE commands to find the device with the lowest BRN; issuing a WITHDRAW command to remove the device with the lowest BRN from consideration; setting the DALI search address to its maximum value; issuing a further COMPARE command to detect whether any further devices are present, the presence of the further devices being determined by observing a response to the further COMPARE command.
• Each Short Address SA occupied with no conflict detected may be determined by sending a QUERY CONTROL GEAR SA command in turn for each DALI Short Address in the DALI Short Address space and reckoning that a Short Address is occupied with no conflict detected if a DALI Yes is received.
• any one of the aspects mentioned above may include any of the features of any of the other aspects mentioned above and may include any of the features of any of the embodiments described below as appropriate.
• the invention provides a reliable method for determining when two devices on a DALI bus have the same Short Address, SA.
• the binary random number BRN of devices in conflict is used to distinguish between them.
• the method of the invention relies on the use of a minimal subset of the available DALI commands.
• the commands used are those normally used for device discovery and Short Address assignment and as such would be available in all DALI compliant devices and even devices that are barely DALI compatible.
• the RANDOMISE command is used to make a device pick a Binary Random Number, or BRN, which is a 24 bit number.
• BRN Binary Random Number
• Three "Search Address" commands, SEARCHADDRH, SEARCHADDRM and SEARCHADDRL allow a 24 bit DALI Search Address to be set.
• the presence of a device with a BRN less than the DALI Search Address can be ascertained by a COMPARE command to which all devices with a BRN less than or equal to the DALI Search Address will respond.
• the method of the invention To determine if there is a conflict for a specific Short Address, SA, the method of the invention first issues an INITIALISE command with the Short Address SA so that only devices with the Short Address SA will respond.
• the DALI search address is then set to its maximum and a first COMPARE command is issued to see if any devices are present. If any devices are present the DALI search address is repeatedly reduced and COMPARE commands issued to find the device with the lowest binary random number, BRN. This device is then removed by a WITHDRAW command. To find if another device is present the DALI search address is set to its maximum again and a further COMPARE command issued. If there is a response to the further COMPARE command or a framing error is detected it is concluded that a second device is present.
• RANDOMISE command is issued after the INITIALISE so that the devices each choose a new BRN. This step may be needed as non-compliant devices may not have a truly random BRN.
• test algorithm can be limited to those Short Addresses for which a DALI Yes was received, but no conflict detected.
• the method will miss a conflict if two devices have the same BRN, however the probability of this happening is very unlikely, being 1 in 2 24 . If this probability is deemed too high it can be reduced to 1 in 2 48 by simply repeating the method. The method will inherently produce no false positives.
• the method will work with all DALI Compliant and DALI Compatible/Controllable devices as the commands used are the minimum subset of commands that a device must support in order to obtain a DALI Short Address.

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• 2014
  • 2014-01-28 AU AU2014200439A patent/AU2014200439B1/en active Active
  • 2014-02-12 EP EP14154801.6A patent/EP2900041A3/fr not_active Withdrawn

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