Patent Description:
Smart objects are devices whose primary function is augmented with intelligent behavior and communication capabilities. Many everyday devices can be utilized more effectively, or in new ways, by embedding some intelligence in them. This trend is already apparent in some lighting products for the home and office market. Examples are daylight sensing or presence detection. These are simple examples of combining several objects with communication capabilities and making them more than the sum of their parts. As more and more devices will be equipped with micro processors and communication capabilities, more complex inter-device behaviors will emerge.

In order to control a luminaire or other load devices, it is very common today to send control signals from a (central) controller to the luminaire. For example, Digital Addressable Lighting Interface (DALI) and Digital Multiple (DMX) are very well known protocols to send commands for e.g. dimming from a light controller to a luminaire. DALI or DMX signals are distributed to the luminaires by wires and the luminaires are connected to the mains by separate and different wires.

A very likely candidate for a new communication backbone is the Internet, enabled through Ethernet or other LAN networking. Ethernet has the major advantage that it is everywhere, and due to the massive volumes involved, equipping a device with Ethernet communication means can be easily done at low costs. Ethernet was developed around <NUM> by Xerox and has seen multiple upgrades and improvements since. Ever since Ethernet transitioned to the well known 8P8C/10BASE-T (or RJ45) connector and cabling, it has enjoyed full backward compatibility with older devices. Due to the enormous amount of devices compatible with this technology, this form of Ethernet is supposed to survive for many more years.

Most traffic on Ethernet networks is comprised of Internet Protocol (IP) packets. The Internet Protocol, standardized into RFC <NUM> around <NUM>, is the backbone of the Internet today. It allows packets to travel on this network in an efficient and robust way. More and more devices are joining the Internet, and most of them are not traditional personal computers (PC's) or laptops. The cellphone revolution put a communication device in everyone's pocket. The current smartphone revolution will connect everyone permanently to the Internet. This means that everyone carries devices that can interact with smart objects around us in several ways.

A very interesting recent addition to Ethernet is the capability to also deliver DC power over the Ethernet cables, while remaining fully compatible with equipment that does not make use of this. First standardized in <NUM>, the IEEE <NUM>. 3af standard allows up to 15W of consumption by the Ethernet device. A second standard developed in <NUM> pushes this to 25W of power. The reason for this conservative limit is the desire to be compatible with thick bundles of cable. For some use cases this is not a requirement and manufacturers have created higher power Power over Ethernet (PoE) extensions. Power supply manufacturers are even offering products that deliver up to 95W per Ethernet port or a power module with power transfer capabilities of up to 200W over a single Ethernet cable. These high power extensions to PoE (not compliant with any IEEE standard, but usually providing a level of compatibility) are mostly used for emerging applications such as PoE laptops, televisions and high performance cameras. Although such power levels clearly require consideration on cable layout, it provides the potential to power even very powerful luminaries directly from the Ethernet switch.

PoE is a standardized way to transfer power and data to a device. PoE is increasingly used for e.g. surveillance cameras, Voice over IP (VoIP) phones, computer monitors and even luminaires. It can be used for all kinds of low power loads like lighting equipment (sensors, switches, light sources etc.) or entertainment appliances like active speakers, internet radios, DVD player, set-top boxes and even TV sets. An advantage of this is that the power and the control data are transmitted through the same cable. This means that it is not necessary to install separate cables for power and for data (as is the case if data is provided by e.g. DALI). For PoE, Cat5 cables can be used. These cables are generally available in a wide variety of lengths and at very low cost. Alternatively Cat6 or Cat7 cables can be used.

Most PoE switches offer the possibility to manage the ports through commands according to the Simple Network Management Protocol (SNMP). SNMP enables e.g. the following functions:.

Alternatively the UI <NUM> can be a dedicated device (e.g. a panel) providing the control data for the luminaires <NUM>-<NUM> to <NUM>-N via the Ethernet connection <NUM>.

The IP-controlled luminaires <NUM>-<NUM> to <NUM>-N offer many advantages, as described above. However, the cost is high due to the need for Ethernet in each luminaire. In addition, when the luminaires <NUM>-<NUM> to <NUM>-N are switched off, there is still some power consumption in the system since Ethernet is still active in each luminaire and since the PSU <NUM> in the PoE switch <NUM> is still on.

A further disadvantage is the size of the driver <NUM> that has to be accommodated in the luminaires <NUM>-<NUM> to <NUM>-N. For some luminaire types this size is no issue, but for some luminaire types, miniaturization is a value driver.

<CIT> discloses a management agent which has access to power output control circuitry of a digital electronic communication switch, a power meter, a load sharing means, and the ability to manage the power of switching circuits in the switch. The power meter enables the management agent to identify the power consumed by the switching circuits that are enabled and operational. This information, coupled with knowledge of the power allocated to each port via PoE, and policy information which specifies power allocation preferences is used in a two-pass power management method.

<CIT> discloses a communication port management apparatus. An SNMP program actuated on a computer successively inquires of network devices about their settings and statuses. Each of the network devices having received such an inquiry returns the status and setting of each port. The computer (SNMP program), based on this response, determines whether or not there is any inconsistency between the status and the setting of any port, and sets the network device containing the port to disable the port if a status-setting inconsistency has been detected.

The invention is carried out as described in the appended claims.

Embodiments of the present invention are now described based on a power distribution control system for a lighting system where individual luminaires are switched on at least one SNMP-controlled PoE switch.

A basis for the proposed embodiments is that PoE does not have to be combined with IP control. The PoE standard is specifically designed to allow PoE to be used without any IP control, or even without Ethernet data at all. This means that equipment can make use of PoE without the associated cost, complexity and power consumption of an IP node, saving a microcontroller and Ethernet transceiver. In the following embodiments, low cost luminaires are provided as so called 'dumb lamps' which do not feature intelligence or means to communicate, and a functional lighting system with these kind of luminaires is proposed.

The minimum amount of control that must be implemented is to be able to switch the dumb lamps on or off. With PoE, the mains supply to the PoE switch can be switched, but this is not desired in a PoE lighting system. This has the effect of switching on/off all luminaires that are connected to that switch. This would however also break the data link of all devices connected to that switch. Therefore, it should be possible to switch individual luminaires and also connect devices to the switch that require a continuous data link. Furthermore, the switching process may be too slow. It could take more than <NUM> for lights to turn on after the mains is applied. The reason is that PoE authentication can take up to <NUM>, and is done port by port.

According to various embodiments, the proposed power distribution control system comprises of PoE-only luminaires (i.e. dumb lamps) and uses a sensor or UI element as a control element to issue Simple Network Management Protocol (SNMP) commands to control lighting. SNMP is a protocol used to control various network equipments. It is used for instance by network administrators to determine which ports on a switch are used and even which Medium Access Control (MAC) addresses are associated with that port. SNMP is a common feature offered on high end professional switches.

Using SNMP is not the only way to control lighting. It is only described here as an example. Any protocol understood by a switch or midspan would suffice to accomplish the same purpose.

Furthermore, automatic commissioning between the control device and dumb PoE-only luminaires is proposed. The required link can be automatically formed between devices that are located on the same network switch (i.e. PoE switch). To achieve this, individual ports of the PoE switch are switched on and off by making use of SNMP.

<FIG> shows a schematic block diagram of a power distribution control system according to a first embodiment with an exemplary number of four dumb lamps <NUM>-<NUM> to <NUM>-<NUM> without any significant processing and/or communication capability. The dumb lamps <NUM>-<NUM> to <NUM>-<NUM> are powered by PoE but do not possess any significant processing/communication capability except what is necessary to transfer power via PoE (this may be embedded in the PoE power distribution integrated circuit). When voltage is applied through PoE, they will turn on and when there is no power, they will obviously be off.

The dumb lamps <NUM>-<NUM> to <NUM>-<NUM> or other kind of dumb loads are connected to a PoE switch <NUM>. On the PoE switch <NUM> one or more controllers (i.e. on/off switches) <NUM> are provided with IP node functionality and SNMP capability. Furthermore, the supply of data and power to the ports <NUM>-<NUM> to <NUM>-<NUM> is achieved via a layer-<NUM> network switch <NUM> based on respective MAC addresses. An uplink port (UL) <NUM> is provided for IP uplink traffic via a connection <NUM> to the Internet.

The power distribution control system automatically works such that toggling a light switch <NUM> (i.e. a lighting control switch or lighting controller) connected to an Ethernet port P5 of the PoE switch <NUM> disables supply of power from a main power supply unit (PSU) <NUM> via PoE connections P to those ports (P1 to P4) <NUM>-<NUM> to <NUM>-<NUM> of the PoE switch <NUM> that do not contain an IP node. Thus, to those ports to which the dumb lamps <NUM>-<NUM> to <NUM>-<NUM> are connected.

The light switch <NUM> is powered via a PoE connection P and sends commands via an Ethernet data connection D to the PoE switch <NUM> to switch specific ports on and off. The light switch <NUM> may be implemented as a simple wall switch or a sensor connected to the same Ethernet network as the PoE switch <NUM> and can switch on and off specific ones or all of the dumb lamps <NUM>-<NUM> to <NUM>-<NUM> when presence of people is detected. This can be done by sending commands to the PoE switch <NUM> to switch on and off specific ones or all of the PoE ports <NUM>-<NUM> to <NUM>-<NUM>.

As an alternative option, the light switch <NUM> may be implemented as a UI adapted to manually switch off specific ones or all of the PoE ports <NUM>-<NUM> to <NUM>-<NUM>.

As a further option, the light switch <NUM> may be implemented as a building management system which gets input from sensors and other devices and has a program running that controls the lighting (e.g. depending on the time of the day, day of the week).

To achieve this, the IP node of the light switch <NUM> must be able to figure out the IP address of the PoE switch <NUM> it is connected to. If it knows the IP address of the PoE switch <NUM> it is connected to, the IP node of the light switch <NUM> can then use SNMP to enable or disable power to the dumb loads. It also needs to know which of the ports (i.e. P1 to P4 in <FIG>) of the PoE switch <NUM> has a dumb PoE lamp connected thereto, and which of the ports (i.e. P5 in <FIG>) has a full IP node connected thereto. Only the dumb nodes at ports P1 to P4 should be switched.

Thus, the light switch <NUM> is capable of enabling/disabling PoE power supply individually per PoE port and querying MAC addresses lookup tables via SNMP. More specifically, the light switch <NUM> may discover what PoE switch it is connected to by employing an IP network scan and probing for its own MAC address in the cache tables of SNMP compatible network switches. Additionally, a way in which the light switch <NUM> may discover which PoE ports of the switch should be turned on/off when the light switch <NUM> is toggled is by checking which MAC cache tables of a certain PoE port are empty while a PoE device is present on the other side. An alternative is to simply look for PoE ports that do not have link-up, or have empty MAC cache tables.

The PoE switch <NUM> may be implemented by means of a midspan which then can be managed by means of SNMP commands in order to allow power-on/off control for certain ports. A midspan contains the power train of PoE without any data switching functionality. When the PoE switch <NUM> is a switch, it is commonly called an endspan or endpoint. Otherwise, if it is an intermediary device between a non-PoE capable switch and a PoE device, it is called a midspan. For example, an external PoE injector is a midspan device. A midspan does not provide Ethernet to its ports. It does allow a data connection if used in combination with a switch. This provides the advantages of further cost reduction and further power reduction. On the other hand, a PoE switch combines the functions, providing both data and power. This provides the advantages that low-cost luminaires (only on/off functionality) can be combined with conventional luminaires having intelligence and receiving Ethernet commands enabling all sorts of advanced features (e.g. dimming).

In a modification of the first embodiment, the PoE switch <NUM> may be adapted to switch its main PSU (Power Supply Unit) <NUM> on and off. If all ports P1 to P5 are switched off, the main PSU <NUM> can be switched off, in order to reduce standby power. Additionally, the PoE switch <NUM> may have an auxiliary PSU (not shown in <FIG>) with a lower voltage and lower power for the microprocessors. This PSU will stay on to receive commands to switch on the main PSU <NUM>.

<FIG> shows a flow diagram of an automatic system configuration procedure according to a second embodiment where a lighting control device (e.g. the light switch <NUM> of <FIG>) controls PoE ports of a PoE switch with commands according to the SNMP protocol.

The procedure starts in step S400. First, the IP node of the lighting control device must find out the IP address of the PoE switch it is connected to. In step S401, this node will receive an IP address and network mask from a Dynamic Host Configuration Protocol (DHCP) server and can then scan all the IP addresses of its subnet to find hosts that offer SNMP. DHCP is a standardized networking protocol used on IP networks that dynamically configures IP addresses and other information that is needed for Internet communication. DHCP allows computers and other devices to receive an IP address automatically from a central DHCP server, reducing the need for a network administrator or a user from having to configure these settings manually.

In the next step S402 the IP node of the lighting control device determines if the host which offers SNMP is a switch and if the IP node of the lighting controller is connected to that switch. This can be done by querying which MAC addresses are stored for each network port. An SNMP host that is not a switch will not have the registers associated with the MAC list of a network switch. In step S403 the IP node of the lighting controller checks whether its MAC address has been found in one of the registers. If no IP address has been found in step S403, the procedure jumps back to step S401 and repeats the scanning process. As an alternative, the procedure may be stopped here. Otherwise, if a relevant IP address has been found in step S403, the lighting controller has discovered the IP address of the SNMP node of the PoE switch it is connected to and the procedure proceeds to step S404 to find out which ports on the PoE switch should be turned on/off.

Now that the lighting controller knows the IP address of the SNMP node on the switch it is connected to, it can monitor in step S404 the MAC lists that the discovered PoE switch maintains. A port with no associated MAC addresses is either not connected, or contains only PoE equipment without IP capabilities. In the next step S405 the lighting controller checks if port(s) with no associated MAC address have been found. If not, the procedure jumps back to step S404 and repeats the monitoring process. As an alternative, the procedure may be stopped here. If the lighting controller determines in step S405 that at least one port with no associated MAC address has been found, the procedure proceeds to step S406 and the detected ports are memorized (e.g. stored in a look-up table) for subsequent switching operation and the power distribution control system is now configured for proper operation. In step S407, the procedure ends.

The above procedure of <FIG>, i.e. finding IP address of switch connected to, and finding out which ports contain dumb lamps, can be implemented in software by using standard SNMP commands on the IP node of the lighting controller.

With the above embodiments, low complexity, small size and low power consumption of the power distribution system can be achieved when only minimal functionality of the controlled load devices is required. In particular, the power consumption is reduced when the controlled load devices are off. Moreover, the size of the luminaires can be minimized since no intelligence needs to be implemented. However, the luminaires and the PoE switch are still compatible with more advanced PoE lighting systems. This is e.g. beneficial in any situation where advanced controls are not needed. It can seamlessly combines with intelligent luminaires.

To summarize, a system for controlling distribution of power to load elements via LAN connections has been described. Low cost luminaires or other load elements can be powered via LAN connections (e.g. by power over Ethernet (PoE)) without featuring an Internet Protocol (IP) node. This is attractive because with such a system the installation cost down benefits of PoE can be applied also to installations that do not require advanced controls. This means that to switch them on or off, the power supply on the LAN port of the switch must be enabled or disabled. When load elements and load controllers (e.g. lighting controllers or light switches) are connected to the same switch, they are automatically paired to each other. This can be achieved through use of a network management protocol capability that some network switches have. This allows for easy installation and automatic intuitive commissioning.

The invention is not limited to the disclosed embodiment with the lamps or luminaires as load devices. It can be implemented in connection with any type load devices for DC distribution networks, such as all kinds of low power loads like lighting equipment (sensors, switches, light sources etc.) or entertainment appliances like active speakers, internet radios, DVD player, set-top boxes and even television (TV) sets.

The proposed control system can be used to implement minimal control features into a PoE lighting network. It will provide simple on/off functionality and automatic commissioning based on the physical network infrastructure.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. A single processor or other unit may fulfil the functions of several items recited in the claims.

It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways, and is therefore not limited to the embodiments disclosed, as far as it falls within the scope of the appended claims.

It should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to include any specific characteristics of the features or aspects of the invention with which that terminology is associated.

Claim 1:
A control device (<NUM>) for controlling distribution of power to load elements (<NUM>-<NUM> to <NUM>-<NUM>) connected to a Power over Ethernet, PoE, network switch, via LAN network connections, wherein said control device (<NUM>) is adapted to discover a PoE network switch (<NUM>) it is connected to by employing a network scan and probing for its own network address in cache tables of a network management protocol compatible network switch; wherein said control device (<NUM>) stores in a lookup table LAN ports (<NUM>-<NUM> to <NUM>-<NUM>) of the PoE network switch (<NUM>), and when the load devices and the control device are connected to said PoE network switch they are automatically paired to each other, and wherein said control device (<NUM>) is adapted to issue control commands of a network management protocol to said detected PoE network switch (<NUM>) in order to switch on or off the LAN ports (<NUM>-<NUM> to <NUM>-<NUM>) of said PoE network switch (<NUM>), through which said power is supplied to respective ones of said load elements (<NUM>-<NUM> to <NUM>-<NUM>), wherein said network management protocol is the Simple Network Management Protocol, SNMP, wherein Power over Ethernet, PoE, is used for said distribution of power.