Patent Publication Number: US-2007110026-A1

Title: Systems and methods for dual power and data over a single cable

Description:
This disclosure relates to power and data systems and methods, and more particularly to systems and methods that can simultaneously provide independent power and data to two separate Ethernet devices over a single Ethernet cable.  
     BACKGROUND AND SUMMARY  
      The IEEE standards 802.3-2000 and 802.3af-2003, which are incorporated herein by reference, relate to Ethernet devices and powering remote devices over an Ethernet based network. Devices communicating according to the IEEE 802.3 standard use RJ-45 connectors and four pairs of twisted pair cables. The IEEE 802.3af standard amended the IEEE 802.3 standard to include “Power of Ethernet” (PoE) capability, which is the ability to directly provide power to an end station over two of the twisted pair cables.  
      Under IEEE 802.3af, two schemes, Scheme A and Scheme B, exist for Power over Ethernet (PoE). In Scheme A, Power Sourcing Equipment (PSE), usually present in a Hub/Switch, supplies power on the same two twisted pairs that are used for transmitting data. The data lines are transformer coupled and the power supply is sourced into the secondary winding of the transformer from the PSE. On a Powered Device (PD) side, the data lines are transformer coupled and power is obtained from the primary coils of the transformer. In Scheme B, the PSE supplies power directly to the PD over unused twisted pairs. The IEEE 802.3af standard mandates that the PD be able to accept power from both schemes.  
      The PoE standard thus enables remote devices (e.g., VoIP phones or Wireless Access Points) to operate without a separate power source. The elimination of line voltage AC power simplifies equipment installation and fosters safety. Adding additional remote Powered Devices, however, requires additional Ethernet cabling from the Power Sourcing Equipment.  
      The systems and methods disclosed herein reduce additional cabling requirements. An example system and corresponding method for providing power and data to at least two Ethernet devices over a common Ethernet cable includes a combiner circuit and a splitter circuit. The combiner circuit receives first and second Ethernet cables and is configured to route power and data signals communicated over the first and second Ethernet cables over a common cable. The splitter circuit is configured to receive the common cable and route the power and data signals routed over the common cable over third and fourth Ethernet cables. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIGS. 1A-1D  depict schematic diagrams of RJ-45 connectors and cables;  
       FIGS. 2A and 2B  depict high level block diagrams of two schemes for remote powering from an endpoint PSE according to IEEE 802.3af;  
       FIGS. 3A-3C  are schematic diagrams of an example embodiment of a dual power and data system for remote powering from an endpoint PSE;  
       FIGS. 4A-4C  are schematic diagrams of another example embodiment of a dual power and data system for remote powering from an endpoint PSE;  
       FIG. 5  is a schematic diagram of another example embodiment of a dual power and data system for remote powering from an endpoint PSE; and  
       FIG. 6  is a flowchart depicting a method for providing data and power over a common cable to two independent devices; and  
       FIG. 7  is another flowchart depicting a method for providing data and power over a common cable. 
    
    
     DETAILED DESCRIPTION  
       FIGS. 1A-1D  depict schematic diagrams of RJ-45 connectors and cables. The RJ-45 connectors have eight pins per connector.  FIG. 1A  depicts a female RJ-45 connector  100  comprising an input  101  and eight pins  102 . The female RJ-45 connector  100  typically is located at a termination point such as, for example, a computer, a switch, a hub, etc.  FIG. 1B  depicts a male RJ-45 connector  110  having eight pins  111  and attached to an Ethernet cable  120 . The male RJ-45 connector  110  typically is connected to the Ethernet cable  120  and is used to connect termination points.  FIG. 1C  depicts a cross-sectional view of the Ethernet cable  120 . The Ethernet cable  120  comprises a first twisted pair connection  130 , a second twisted pair connection  140 , a third twisted pair connection  150 , and a fourth twisted pair connection  160 .  FIG. 1D  depicts a table listing the pin connections of the RJ-45 connectors  100 ,  110 . Pins  1  and  2  connect to the first twisted pair connection  130 , and pins  3  and  6  connect to the fourth twisted pair connection  160 . The remaining four pins ( 4 ,  5 ,  7 , and  8 ) of the RJ-45 connector, which comprise the second twisted pair connection  140  and the third twisted pair connection  150 , are not used in the original IEEE 802.3 standard.  
      The IEEE 802.3af standard amended the IEEE 802.3 standard to include the PoE capability to directly provide power over two of the twisted pair cables to an end station. The two PoE schemes—Scheme A and Scheme B—are shown in  FIGS. 2A and 2B , respectively. The IEEE 802.3af standard mandates that the Powered Device be able to accept power from the Power Sourcing Equipment under both schemes.  
       FIG. 2A  depicts a high level block diagram of a system  200  utilizing Scheme A. In Scheme A, the Power Sourcing Equipment supplies power on the same two twisted pairs that are used for data (pairs  130  and  160 ).  
      The system  200  comprises a switch/hub  210 , a first twisted pair connection  130 , a second twisted pair connection  140 , a third twisted pair connection  150 , a fourth twisted pair connection  160 , and a powered end station  230 .  
      The switch/hub  210  comprises power sourcing equipment (PSE)  211  having a positive power output lead  213  and a negative power output lead  214 ; a first physical layer (PHY) controller  212 ; a PHY controller  213 ; a first transformer  201 ; and a second transformer  202 . The positive output lead  213  is connected to the center tap of the secondary of the first transformer  201 , and the negative output lead  214  is connected to the center tap of the secondary of the second transformer  202 . The primary of the first transformer  201  is connected to the first physical layer controller  212 , and the primary of the second transformer  202  is connected to the second physical layer controller  213 . The output leads of the secondary of the first transformer  201  are connected to the first twisted pair connection  130 , and the output leads of the second transformer  202  are connected to the fourth twisted pair connection  160 .  
      The powered end station  230  comprises a powered device  231  having a positive power input lead  232  and a negative power input lead  233 ; a third transformer  203 ; and a fourth transformer  204 . The second end of the first twisted pair connection  130  is connected to the primary of the third transformer  203 , and the second end of the fourth twisted pair connection  160  is connected to the primary of the fourth transformer  204 . The center tap of the primary of the third transformer  203  is connected to the positive input lead  232 , which, in turn, is connected to the powered device  231 . The center tap of the primary of the fourth transformer  204  is connected to the negative input lead  233 , which, in turn, is connected to the powered device  231 .  
      In operation, the power sourcing equipment  211  supplies both power and data over the first twisted pair connection  130  and the fourth twisted pair connection  160 . At the switch/hub  210 , the transformers  201  and  202  couple the data in the form of an AC waveform on the primary with DC power from the PSE  211  on the secondary. At the powered end station  230 , the transformers  203  and  204  decouple the data in the form of an AC waveform on the secondary and the DC power on the primary. The positive power input lead  232  of the PD  231  is operatively connected to the positive power output lead  213  of the PSE  211  through the first twisted pair connection  130 , the center tapped primary of the third transformer  203 , and the center tapped secondary of the first transformer  201 . The negative power input lead  233  of powered device  231  is operatively connected to the negative power output lead  214  of the PSE  211  through the fourth twisted pair connection  160 , the center tapped primary of the fourth transformer  204 , and the center tapped secondary of the second transformer  202 .  
       FIG. 2B  depicts a high level block diagram  250  of a system utilizing Scheme B. In Scheme B, the PSE  211  supplies power to the PD  231  over the unused twisted pairs (pairs  140  and  150 ).  
      The system  250  comprises a switch/hub  260 , a first twisted pair connection  130 , a second twisted pair connection  140 , a third twisted pair connection  150 , a fourth twisted pair connection  160 , and a powered end station  230 . The switch/hub  250  comprises a PSE  211  having a positive power output lead  261  and a negative power output lead  262 ; a first PHY controller  212 ; a second PHY controller  213 ; a first transformer  201 ; and a second transformer  202 . The positive output lead  261  is connected to the second twisted pair connection  140 , and the negative output lead  262  is connected to the third twisted pair connection  150 . The primary of the first transformer  201  is connected to the first PHY controller  212 , and the primary of the second transformer  202  is connected to the second PHY controller  213 . The output leads of the secondary of the first transformer  201  are connected to the first twisted pair connection  130 , and the output leads of the second transformer  202  are connected to the fourth twisted pair connection  160 .  
      The powered end station  230  comprises a PD  231  having a positive power input lead  234  and a negative power input lead  235 ; a third transformer  203 ; and a fourth transformer  204 . The second end of the first twisted pair connection  130  is connected to the primary of the third transformer  203 , and the second end of the fourth twisted pair connection  160  is connected to the primary of the fourth transformer  204 . The third transformer  203  and the fourth transformer  204  are located in the powered end station  230 . The second end of the second twisted pair connection  140  within the powered end station  230  is connected to the positive input lead  234 . The second end of the third twisted pair connection  150  within the powered end station  230  is connected to the negative input lead  235 . The center taps of the primary of the third transformer  203  and the fourth transformer  204  are connected to the powered device  231 .  
      In operation, the power sourcing equipment  211  supplies data over the first twisted pair connection  130  and the fourth twisted pair connection  160 , and supplies power over the second twisted pair connection  140  and the third twisted pair connection  150 . The positive power input lead  234  of powered device  231  is operatively connected to the positive power output lead  261  of the PSE  211  through the second twisted pair connection  140 . The negative power input lead  235  of powered device  231  is operatively connected to the negative power output lead  262  of the PSE  211  through the third twisted pair connection  150 , the center tapped primary of the fourth transformer  204 , and the center tapped secondary of the second transformer  202 .  
       FIGS. 3A-3C  are schematic diagrams of an example embodiment of a dual power and data system for remote powering from an endpoint PSE in accordance with Scheme A. The dual power and data system  300  comprises switch/hub equipment  210 - 1 ,  210 - 2 ; cables  120 - 1 ,  120 - 2 ,  120 - 3 ,  120 - 4 ; a common cable  120 - 5 ; a combiner  310 ; a splitter  320 ; and powered end stations  230 - 1  and  230 - 2 . The cables  120 - 1 ,  120 - 2 ,  120 - 3 ,  120 - 4  and the common cable  120 - 5  each comprise four twisted pair connections, such as an Ethernet or Cat 5 cable. The switch/hub equipment  210 - 1  and  210 - 2  are configured to provide power and data according to Scheme A  200  for remote powering.  
      The dual power and data system  300  combines two cables  120  onto one single common cable  120 - 5  by wiring the twisted pairs to utilize the unused twisted pair connections in the common cable  120 - 5 . The powered end station  230 - 1  is operatively connected to the switch/hub equipment  210 - 1  through the cable  120 - 3 , the splitter  320 , the common cable  120 - 5 , the combiner  310 , and the cable  120 - 1 . The powered end station  230 - 2  is operatively connected to the switch/hub equipment  210 - 2  through the cable  120 - 4 , the splitter  320 , the common cable  120 - 5 , the combiner  310 , and the cable  120 - 2 . The common cable  120 - 5  may comprise existing Ethernet cabling.  
      The combiner  310  is configured to route the signals for cables  120 - 1  and  120 - 2  over a common cable  120 - 5  by utilizing all four twisted pair connections in the common cable  120 - 5 . The combiner  310  comprises a twisted pair  311  connected to a first twisted pair on the switch/hub equipment  210 - 1  by the cable  120 - 1  and to a first twisted pair in the common cable  120 - 5 ; a twisted pair  312  connected to a fourth twisted pair on the switch/hub equipment  210 - 1  by the cable  120 - 1  and to a second twisted pair in the common cable  120 - 5 ; a twisted pair  313  connected to a first twisted pair on the switch/hub equipment  210 - 2  by the cable  120 - 2  and to a third twisted pair in the common cable  120 - 5 ; and a twisted pair  314  connected to a fourth twisted pair on the switch/hub equipment  210 - 2  by the cable  120 - 2  and to a fourth twisted pair in the common cable  120 - 5 .  
      The splitter  320  is configured to route the signals received from the common cable  120 - 5  over cables  120 - 3  and  120 - 4 . The splitter  320  comprises a twisted pair  321  connected to the first twisted pair in the common cable  120 - 5  and to a first twisted pair on the powered end station  230 - 1  by the cable  120 - 3 ; a twisted pair  322  connected to the second twisted pair in the common cable  120 - 5  and to a fourth twisted pair on the powered end station  230 - 1  by the cable  120 - 3 ; a twisted pair  323  connected to the third twisted pair in the common cable  120 - 5  and to a first twisted pair on the powered end station  230 - 2  by the cable  120 - 4 ; and a twisted pair  324  connected to the fourth twisted pair in the common cable  120 - 5  and to a fourth twisted pair on the powered end station  230 - 2  by the cable  120 - 4 .  
       FIG. 3B  is a schematic diagram depicting an example combiner  310  for a dual power and data system  300  according to a Scheme A embodiment. The combiner  310  comprises a twisted pair  311  connected to a first twisted pair  130 - 1  in a cable  120 - 1  and to a first twisted pair  130 - 5  in a common cable  120 - 5 ; a twisted pair  312  connected to a fourth twisted pair  160 - 1  in the cable  120 - 1  and to a second twisted pair  140 - 5  in the common cable  120 - 5 ; a twisted pair  313  connected to a first twisted pair  130 - 2  in a cable  120 - 2  and to a third twisted pair  150 - 5  in the common cable  120 - 5 ; a twisted pair  314  connected to a fourth twisted pair  160 - 2  in the cable  120 - 2  and to a fourth twisted pair  160 - 5  in the common cable  120 - 5 ; and a termination plug  315  attached to a second twisted pair  140 - 1 , a third twisted pair  150 - 1 , a second twisted pair  140 - 2 , and a third twisted pair  150 - 3 . The termination plugs  315  terminate the unused twisted pairs in the cables  120 - 1  and  120 - 2 .  
       FIG. 3C  is a schematic diagram depicting an example splitter  320  for a dual power and data system  300  according to a Scheme A embodiment. The splitter  320  comprises a twisted pair  321  connected to a first twisted pair  130 - 5  in a common cable  120 - 5  and to a first twisted pair  130 - 3  in a cable  120 - 3 ; a twisted pair  322  connected to a second twisted pair  140 - 5  in the common cable  120 - 5  and to a fourth twisted pair  160 - 3  in the cable  120 - 3 ; a twisted pair  323  connected to a third twisted pair  140 - 5  in the common cable  120 - 5  and to a first twisted pair  130 - 4  in a cable  120 - 4 ; and a twisted pair  324  connected to a fourth twisted pair  160 - 5  in the common cable  120 - 5  and to a fourth twisted pair  160 - 4  in the cable  120 - 4 ; and a termination plug  315  attached to a second twisted pair  140 - 3 , a third twisted pair  150 - 3 , a second twisted pair  140 - 4 , and a third twisted pair  150 - 4 . The termination plugs  315  terminate the unused twisted pairs in the cables  120 - 3  and  120 - 4 .  
       FIGS. 4A-4C  are schematic diagrams of an example embodiment of a dual power and data system for remote powering from an endpoint PSE in accordance with Scheme B. The dual power and data system  400  comprises switch/hub equipment  260 - 1 ,  260 - 2 ; cables  120 - 1 ,  120 - 2 ,  120 - 3 ,  120 - 4 ; a common cable  120 - 5 ; a combiner  410 ; a splitter  420 ; and powered end stations  230 - 1 ,  230 - 2 . The cables  120 - 1 ,  120 - 2 ,  120 - 3 ,  120 - 4  and the common cable  120 - 5  each comprise four twisted pair connections, such as an Ethernet or Cat 5 cable. The switch/hub equipment  260 - 1  and  260 - 2  are configured to provide power and data according to Scheme B for remote powering.  
      In Scheme B, data and power are provided on separate twisted pair connections in a cable. The dual power and data system  400  utilizes a combiner  410  and a splitter  420  to combine power and data on a single twisted pair and to utilize all four twisted pairs in a cable  120 . Accordingly, two powered end stations  230 - 1  and  230 - 2  may be powered by one cable. The powered end station  230 - 1  is operatively connected to the switch/hub equipment  260 - 1  through the cable  120 - 3 , the splitter  420 , the common cable  120 - 5 , the combiner  410 , and the cable  120 - 1 . The powered end station  230 - 2  is operatively connected to the switch/hub equipment  260 - 2  through the cable  120 - 4 , the splitter  420 , the common cable  120 - 5 , the combiner  410 , and the cable  120 - 2 .  
      The combiner  410  is configured to route the signals for cables  120 - 1  and  120 - 2  over a common cable  120 - 5  by utilizing all four twisted pair connections in the common cable  120 - 5 . The combiner  410  comprises four transformers  411 ,  412 ,  413  and  414 , each configured to couple power and data from separate twisted pairs in cables  120 - 1 ,  120 - 2  onto single twisted pairs in the common cable  120 - 5 .  
       FIG. 4B  depicts a schematic diagram of the combiner  410  configured to couple data and power from separate twisted pair connections in cables  120 - 1 ,  120 - 2  onto a single common cable  120 - 5 . The combiner  410  comprises four transformers  411 ,  412 ,  413 ,  414 . The primary of the transformer  411  is connected to a first twisted pair on the switch/hub equipment  260 - 1  by the cable  120 - 1 . The center tap of the secondary of the transformer  411  is connected to a second twisted pair on the switch/hub equipment  260 - 1  by the cable  120 - 1 . The secondary of the transformer  411  is connected to a first twisted pair on the common cable  120 - 5 . The primary of the transformer  412  is connected to a fourth twisted pair on the switch/hub equipment  260 - 1  by the cable  120 - 1 . The center tap of the secondary of the transformer  412  is connected to a third twisted pair on the switch/hub equipment  260 - 1  by the cable  120 - 1 . The secondary of the transformer  412  is connected to a second twisted pair on the common cable  120 - 5 . The primary of the transformer  413  is connected to a first twisted pair on the switch/hub equipment  260 - 2  by the cable  120 - 2 . The center tap of the secondary of the transformer  413  is connected to a second twisted pair on the switch/hub equipment  260 - 2  by the cable  120 - 2 . The secondary of the transformer  413  is connected to a third twisted pair on the common cable  120 - 5 . The primary of the transformer  414  is connected to a fourth twisted pair on the switch/hub equipment  260 - 2  by the cable  120 - 2 . The center tap of the secondary of the transformer  414  is connected to a third twisted pair on the switch/hub equipment  260 - 2  by the cable  120 - 2 . The secondary of the transformer  414  is connected to a fourth twisted pair on the common cable  120 - 5 .  
      The splitter  420  is depicted in  FIG. 4C . The splitter  420  is configured to route the signals received from the common cable  120 - 5  over cables  120 - 3  and  120 - 4 . The splitter  420  comprises four transformers  421 ,  422 ,  423 ,  424  configured to decouple power and data from twisted pairs in the common cable  120 - 5  cables onto separate twisted pairs in cables  120 - 3  and  120 - 4  connected to the powered end stations  230 - 1  and  230 - 2 . The primary of the transformer  421  is connected to a first twisted pair on the common cable  120 - 5 . The center tap of the primary of the transformer  421  is connected to a second twisted pair on the powered end station  230 - 1  by cable  120 - 3 . The secondary of the transformer  421  is connected to a first twisted pair on the powered end station  230 - 1  by cable  120 - 3 . The primary of the transformer  422  is connected to a second twisted pair on the common cable  120 - 5 . The center tap of the primary of the transformer  422  is connected to a third twisted pair on the powered end station  230 - 1  by cable  120 - 3 . The secondary of the transformer  422  is connected to a fourth twisted pair on the powered end station  230 - 1  by cable  120 - 3 . The primary of the transformer  423  is connected to a third twisted pair on the common cable  120 - 5 . The center tap of the primary of the transformer  423  is connected to a second twisted pair on the powered end station  230 - 2  by cable  120 - 4 . The secondary of the transformer  423  is connected to a first twisted pair on the powered end station  230 - 2  by cable  120 - 4 . The primary of the transformer  424  is connected to a fourth twisted pair on the common cable  120 - 5 . The center tap of the primary of the transformer  424  is connected to a third twisted pair on the powered end station  230 - 2  by cable  120 - 4 . The secondary of the transformer  424  is connected to a fourth twisted pair on the powered end station  230 - 2  by cable  120 - 4 .  
       FIG. 5  is a schematic diagram of another example embodiment of a dual power and data system for remote powering from an endpoint PSE. The dual power and data system  500  comprises switch/hub equipment  260 - 1 ,  260 - 2 ; cables  120 - 1 ,  120 - 2 ,  120 - 3 ,  120 - 4 ; a common cable  120 - 5 ; a combiner  410 ; a splitter  320 ; and powered end stations  230 - 1 ,  230 - 2 .  
      The switch/hub equipment  260 - 1 ,  260 - 2  is configured to provide power and data according to Scheme B for remote powering from an endpoint PSE as depicted in  FIG. 2A . In Scheme B, data and power are provided on separate twisted pair connections in a cable. The combiner  410  comprises four transformers  411 ,  412 ,  413 ,  414  configured to couple power and data from separate twisted pairs in cables  120 - 1 ,  120 - 2  onto single twisted pairs in the common cable  120 - 5  as depicted in  FIG. 4B .  
      The combiner  410  connects to the splitter  320  by the common cable  120 - 5 . The splitter  320  comprises a twisted pair  321  connected to the first twisted pair in the common cable  120 - 5  and to a first twisted pair on the powered end station  230 - 1  by the cable  120 - 3 ; a twisted pair  322  connected to the second twisted pair in the common cable  120 - 5  and to a fourth twisted pair on the powered end station  230 - 1  by the cable  120 - 3 ; a twisted pair  323  connected to the third twisted pair in the common cable  120 - 5  and to a first twisted pair on the powered end station  230 - 2  by the cable  120 - 4 ; and a twisted pair  324  connected to the fourth twisted pair in the common cable  120 - 5  and to a fourth twisted pair on the powered end station  230 - 2  by the cable  120 - 4 . The powered end stations  230 - 1 ,  230 - 2  can accept power and data from either Scheme A or Scheme B in accordance with IEEE 802.3af. Thus in this example, the dual power and data system  500  provides power and data from the switch/hub  260 - 1  and  260 - 2  according to Scheme B, and the powered end stations  230 - 1  and  230 - 2  utilize the power and data according to Scheme A.  
       FIG. 6  is a flowchart depicting a method  600  for providing data and power over a common cable to two independent devices. The method  600  comprises connecting a first and a second switch/hub to a combiner, as depicted in step  601 . The first and second switch/hub is configured to provide data and power over an Ethernet cable and may be compliant with IEEE 802.3af power over Ethernet standard. The first and second switch/hub may comprise, for example, a server, a router, a switch, a hub, an Internet appliance, or a modem. The connection between the first and second switch/hub and the combiner may comprise at least two Ethernet cables.  
      The combiner is connected to a first end of a common Ethernet cable, as depicted in Step  602 . The combiner is configured to provide the power and data from the first and second switch/hub to a common Ethernet cable. The combiner may comprise, for example, twisted pair wires configured to route two cables to one cable or a plurality of transformers configured to couple data and power to one cable.  
      A splitter is connected to a second end of the common Ethernet cable, as depicted in Step  603 . The splitter is configured to provide the power and data from the common Ethernet cable to two separate powered devices. The splitter may comprise, for example, twisted pair wires configured to rewire the Ethernet cable to route signals from one cable to two cables or a plurality of transformers configured to decouple data and power to two cables.  
      Two powered devices are connected to the splitter, as depicted in Step  603 . The two powered devices may be connected to the splitter by a plurality of Ethernet cables. The Steps  601 ,  602 ,  603 ,  604  may be completed in any order with the method  600  complete when all steps are completed.  
       FIG. 7  is another flowchart depicting a method  610  for providing data and power over a common cable. Step  611  receives first and second Ethernet cables at a combiner. The first and second Ethernet cables may facilitate PoE according to Scheme A or Scheme B.  
      Step  612  routes power and data signals communicated over the first and second Ethernet cables over common twisted pairs in the common cable. To carry out step  612 , the combiner may be configured to route the power and data signals communicated over the first and second Ethernet cables over common twisted pairs in the common cable as described above.  
      Step  613  receives the common cable at a splitter, and step  614  communicates the power and data signals routed over the common cable over third and fourth Ethernet cables. To carry out step  614 , the splitter may be configured to communicate the power and data signals routed over the common cable over third and fourth Ethernet cables as described above.  
      This written description sets forth the best mode of the invention and provides examples to describe the invention and to enable a person of ordinary skill in the art to make and use the invention. This written description does not limit the invention to the precise terms set forth. Thus, while the invention has been described in detail with reference to the examples set forth above, those of ordinary skill in the art may effect alterations, modifications and variations to the examples without departing from the scope of the invention.