Abstract:
A method and apparatus for remotely controlling a power state of devices comprises interconnecting, with an Ethernet cable, a first multi-function display (MFD) and at least one device for communicating with the first MFD. The first MFD comprises a switch for changing a power state. A power source provides power for the first MFD and the at least one device. The first MFD remotely controls the power state of the at least one device through a control signal output to the Ethernet cable. The at least one device receives the control signal and changes the power state of the at least one device in response to the control signal.

Description:
RELATED APPLICATION 
   The present application is a continuation of and claims priority benefit to U.S. patent application Ser. No. 11/140,792, filed May 31, 2005, entitled “METHOD AND APPARATUS FOR REMOTE DEVICE CONTROL USING CONTROL SIGNALS SUPERIMPOSED OVER ETHERNET.” The above-identified application is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   This invention relates generally to remotely controlling devices which are interconnected, and more particularly, to controlling devices interconnected with Ethernet cable. 
   Multiple sensors are often used aboard a marine craft to provide information to a user. Types of information may be weather, radar, or global positioning, for example. It is helpful to have the different types of information collected and, if possible, integrated together, then displayed on one or more devices. A small boat may utilize a single device for providing information, while larger craft may have multiple devices installed on more than one helm or at different locations on the craft. 
   The sensors and display devices typically run on battery power. To conserve battery power, such as when in a marina overnight, a user may want to turn off the battery powered devices. Some marine craft provide a breaker system which immediately removes power from one or more of the sensors and display devices. Often, however, the sensors and display devices must be individually turned off. If power is not removed, the battery may be drained when the user returns to the marine craft. 
   Some marine craft utilize a large number of sensors and display devices, creating a high level of difficulty with cabling, powering, and interfacing the different products which provide different types of information. In addition, the backlight of the display device consumes a large amount of power and has a limited life. Unfortunately, if power is removed from the display device the data which has been collected or received by the sensors is lost. Some forms of data, such as data received from a satellite, are time consuming to acquire and thus it is not advantageous to turn the display device off. 
   Therefore, a need exists for interconnecting and controlling the power state of multiple sensors and display devices. Certain embodiments of the present invention are intended to meet these needs and other objectives that will become apparent from the description and drawings set forth below. 
   BRIEF DESCRIPTION OF THE INVENTION 
   An apparatus for interconnecting and remotely controlling a power state of devices using an Ethernet cable comprises a first multi-function display (MFD). The first MFD comprises a switch for changing a power state. An Ethernet cable interconnects the first MFD and at least one device which communicates with the first MFD. A power source powers the first MFD and the at least one device, and the first MFD remotely controls a power state of the at least one device through a control signal output to the Ethernet cable. 
   A method for remotely controlling devices using an Ethernet cable comprises connecting a multi-function display (MFD) and at least one device with an Ethernet cable. The at least one device comprises a sensor. A power switch interconnected with the MFD is activated to change a power state of the MFD and the at least one device. A control signal is superimposed on the Ethernet cable and is received at the at least one device. A power state of the at least one device is changed in response to the control signal. 
   A system for remotely controlling a power state of interconnected components comprises a cable interconnecting multiple components. The multiple components further comprise a multi-function device (MFD) comprising a multiprocessor and a switch. The multiprocessor generates a control signal for remotely controlling a power state of the multiple components when the switch is activated. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a network having devices interconnected with an Ethernet cable in accordance with an embodiment of the present invention. 
       FIG. 2  illustrates the Ethernet cable, the MFD and the sensor of  FIG. 1  in accordance with an embodiment of the present invention. 
       FIG. 3  illustrates a network having more than one MFD interconnected with an Ethernet cable in accordance with an embodiment of the present invention. 
       FIG. 4  illustrates the Ethernet cable, the MFDs, and the sensors of  FIG. 3  in accordance with an embodiment of the present invention. 
   

   The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. It should be understood that the present invention is not limited to the arrangements and instrumentality shown in the attached drawings. 
   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates a network  100  having devices interconnected with an Ethernet cable  102  in accordance with an embodiment of the present invention. The network  100  includes a multi-function display (MFD)  104  and a sensor  106  interconnected with the Ethernet cable  102 . The MFD  104  and the sensor  106  are each connected to a ground and battery bus  114  by way of lines  116  and  118 , respectively. It should be understood that one or more battery or power sources may be provided instead of the battery bus  114 . Therefore, only two separate connections, a network connection and a power connection, need to be provided to each MFD  104  and sensor  106 . 
   Some networks utilize IEEE 802.3 af power over Ethernet, which superimposes power over the Ethernet cable to run devices connected to the Ethernet. Thus, if three devices are interconnected on a network with an Ethernet cable, one device can superimpose power over the Ethernet cable to supply the necessary power to the other two devices. However, one or more of the MFD  104  and sensor  106  have a power consumption level that is too large to allow use of the IEEE 802.3 af design. Therefore, the devices, the MFD  104  and the sensor  106 , connected to the Ethernet cable  102  are also connected to the battery bus  114  via lines  116  and  118 . 
   The sensor  106  is a device which collects and sends information to the MFD  104 . For example, the sensor  106  may be a global positioning device (GPS), a fish finder, marine radar, satellite radio receiver, and the like. 
   The MFD  104  has a display  108  and one or more buttons  110 , knobs, switches, or other user interface capability to allow the user to select and input information, and to change the information displayed on the display  108 . It should be understood that the buttons  110  illustrated on  FIG. 1  are exemplary, and that more or less buttons  110  may be provided in different locations on the MFD  104 . In addition, the display  108  may provide touch screen capability, allowing the user to select information directly on the screen using a finger or stylus, for example. The MFD  104  is used for charting, saving way points that indicate places of interest, and displaying information collected by the sensor  106 , such as marine radar and weather. 
     FIG. 2  illustrates the Ethernet cable  102 , the MFD  104  and the sensor  106  of  FIG. 1  in accordance with an embodiment of the present invention. The MFD  104  further comprises a microprocessor  136  for controlling the MFD  104 , processing data, and the like. A switch  112  on the MFD  104  allows the user to change the power state of the MFD  104 , the display  108 , and the sensor  106 .  FIGS. 1 and 2  will be discussed together. 
   The Ethernet cable  102  is a standard Ethernet cable, allowing easy installation and repair for the user. There is no need to create custom cables or connectors. The Ethernet cable  102  may be 100 base-T or 1000 base-T, utilizing 4 pairs of twisted-pair wires  120 - 126 . The network connection at the hardware level uses the OSI data link and physical layers of Ethernet, meaning that a standard Ethernet MAC IC (Media Access Controller, which formats/de-formats application data to Ethernet data link protocol) and PHY IC (electrical driver) can be used. It should be understood that other types of cables may also be used. 
   The MFD  104  and sensor  106  send and receive packets of information over the Ethernet cable  102  using transmit and receive wires, such as wires  120  and  122 . The packets are addressed with a header identifying the intended recipient device. Therefore, the wires  124  and  126  are not used for data transmission. 
   The MFD  104  has a sensor power control output  140  which is connected to an available wire of the Ethernet cable  102 , such as wire  124 . The sensor  106  has a sensor power control input  142  which is connected to the same wire  124 . The wire  124  may be referred to as a sensor power control line  146 . The sensor power control line  146  is an open collector line. Therefore, more than one MFD  104  can be connected to the Ethernet cable  102  and activate the sensor power control line  146  without bus contention. The MFD  104  also has an MFD power control input/output (I/O)  144  connected to the second available wire  126  of the Ethernet cable  102 . The MFD power control I/O  144  is bidirectional and will be discussed further below. 
   The microprocessor  136  and/or the power supply circuitry  138  sense when the switch  112  of the MFD  104  is activated by the user via lines  128  and  130 , respectively. If the MFD  104  is not already powered on, the power supply circuitry  138  is activated and the MFD  104  is powered up. The microprocessor  136  sends a control signal to the sensor power control output  140  via line  132  and pulls the sensor power control line  146  low. The sensor power control line  146  will be held low by the MFD  104  as long as the MFD  104  is in the powered on state. 
   The sensor power control input  142  is connected to power supply circuitry  148  via line  152  within the sensor  106 . When the sensor power control line  146  is pulled low, the low control signal activates the power supply circuitry  148  and the sensor  106  is powered up. Alternatively, the sensor  106  may also utilize a microprocessor  150  which monitors the sensor power control input  142  via line  154  in place of, or in addition to, the power supply circuitry  148 . 
   Once the sensor  106  is powered on, the sensor  106  begins to collect data. The MFD  104  can display the collected data on the display  108  and allow input from the user via the buttons  110 . The user may also input other information into the MFD  104 , such as waypoints indicating places of interest. 
   When the network  100  is in the powered on state, the microprocessor  136  monitors the switch  112 . If the switch  112  is pressed or activated, the microprocessor  136  displays a message on the display  108 . The message requests input from the user to choose or identify whether the network  100 , including the sensor  106  and the MFD  104 , should be powered down, or whether just the display  108  of the MFD  104  should be turned off. 
   Using buttons  110 , the user may select the option to turn the display  108  off to conserve power, extend the life of the display  108 , or because the user currently does not need to access the displayed information. By choosing to turn only the display  108  off, the power is removed from the display  108 , but the MFD  104  remains in a power on state, retains the information previously collected by the sensor  106  and continues to receive information from the sensor  106 . The sensor  106  remains in a power on state. 
   When the display  108  is in the power off state, the microprocessor  136  continues to monitor the switch  112 . When the switch  112  is activated, the microprocessor  136  initiates the restoration of power to the display  108 . 
   Alternatively, the user may select the option to turn off the devices connected to the network  100 . The microprocessor  136  initiates a power down sequence to change the MFD  104  to be in a power off state. The microprocessor  136  also sends a control signal to the sensor power control output  140  and releases the sensor power control line  146 . The microprocessor  150  and/or power supply circuitry  148  of the sensor  150  senses the change in the sensor power control line  146  at the sensor power control input  142  and initiates a power down sequence, changing the power state of the sensor  106  to be a power off state. 
   It should be understood that the functionality of sensing the switch  112 , initiating a change in power state of the MFD  104  and the sensor  106 , and changing the power state of the display  108  may be accomplished by use of microprocessors  136  and  150 , the power supply circuitry  138  and  148 , and/or other hardware and software. Optionally, more than one switch  112  may be provided on each MFD  104 , wherein a separate switch is used to control the power state of the display  108 . Therefore, the functionality is not limited to the methods and apparatus discussed herein. 
     FIG. 3  illustrates a network  200  having more than one MFD interconnected with an Ethernet cable  202  in accordance with an embodiment of the present invention. The network  200  comprises two MFDs  204  and  206  and two sensors  208  and  210 , each of which are connected to a ground and battery bus  216  via lines  220 ,  222 ,  218 , and  224 , respectively. The sensors  208  and  210  may each sense or receive different types of information. For example, the sensor  208  may be a fish finder and the sensor  210  may be a GPS. 
   Each of the MFDs  204  and  206  and the sensors  208  and  210  need only one power connection and one Ethernet connection to interconnect the devices with each other. Each MFD  204  and  206  connected to the Ethernet cable  202  can communicate with and control the sensors  208  and  210 , such as by changing the range, gain, and the like. 
     FIG. 4  illustrates the Ethernet cable  202 , the MFDs  204  and  206 , and the sensors  208  and  210  of  FIG. 3  in accordance with an embodiment of the present invention.  FIGS. 3 and 4  will be discussed together. Although not illustrated for clarity, it should be understood that the Ethernet cable  202  comprises 4 twisted-cable pairs as discussed previously and illustrated in  FIG. 2 . 
   Also, more MFDs and sensors may be installed on the network  200 . For example, a user may wish to install an MFD on each of the fly bridge, the helm, the pilot house and stateroom, creating a network of multiple MFDs which share information. Also, a port expander (not shown) may be used to provide connectivity for multiple devices, and a receiver server (not shown) may be integrated with the network  200  to store large amounts of data. 
   The MFD  204  further comprises a display  226 , buttons  230  for inputting information and changing the display  226 , a microprocessor  250 , and power supply circuitry  252 . The MFD  206  further comprises a display  228 , buttons  232  for input, a microprocessor  254 , and power supply circuitry  256 . The sensor  208  has a microprocessor  262  and power supply circuitry  258 , and the sensor  210  has a microprocessor  264  and power supply circuitry  260 . 
   The MFDs  204  and  206  each have a sensor power control output  234  and  236 , respectively, which is connected to an available wire of the Ethernet cable  202 , such as wire  124  ( FIG. 2 ) of Ethernet cable  102  as discussed previously. This wire may be called a sensor power control line  242 . The sensors  208  and  210  each have a sensor power control input  238  and  240 , respectively, connected to the sensor power control line  242 ; the operation is the same as discussed previously in connection with the sensor power control line  146 . That is, the sensor power control line  242  is an open collector line. Therefore, each of the MFDs  204  and  206  can connect to and activate the sensor power control line  242  without bus contention. 
   In addition, the sensors  208  and  210  may have circuitry to prevent the sensors  208  and  210  from powering on when leakage current is present. By way of example only, multiple MFDs may output leakage current, such as when at a high temperature. Therefore, a minimum current limit on the sensor power control line  242  may be set to protect the sensors  208  and  210  from inadvertent power on. The minimum current limit may be a preset limit, such as 1 mA, or may be based on the number of components within the system  200 . 
   The MFDs  204  and  206  each have a bidirectional MFD power control input/output (I/O)  244  and  246 , respectively, which is connected to the second available wire of the Ethernet cable  202 . The wire may be referred to as an MFD power control line  248 . 
   The power state of the network  200  may be changed by either of the MFDs  204  and  206 . Therefore, when the network  200  is in a power off state, activating either the switch  212  of MFD  204  or switch  214  of MFD  206  initiates power up sequences within the components connected to the Ethernet cable  202 . Therefore, the following discussion will utilize MFD  204 , but it should be understood that the discussion applies equally to MFD  206 . 
   The microprocessor  250  and/or power supply circuitry  252  sense when the switch  212  of the MFD  204  is activated by the user via lines  266  and  268 , respectively. The power supply circuitry  252  is activated and the MFD  204  is powered up. The microprocessor  250  sends a control signal to the sensor power control output  234  via line  270  and pulls the sensor power control line  242  low. The microprocessor  250  may send the control signal either as the MFD  204  is powering up or after the MFD  204  is completely powered on. The sensor power control line  242  will be held low by the MFD  204  as long as the MFD  204  is in the powered on state. 
   The sensor power control input  238  is connected to power supply circuitry  258  and/or microprocessor  262  within the sensor  208  via lines  270  and  272 , and the sensor power control input  240  is connected to power supply circuitry  260  and/or microprocessor  264  within the sensor  210  via lines  274  and  276 . When the sensor power control line  242  is pulled low, the low control signal activates the power supply circuitries  258  and  260  and the sensors  208  and  210  are powered up. 
   At the same time as the MFD  204  is initiating its power up sequence and outputting the control signal on the sensor power control line  242 , the microprocessor  250  outputs a control signal to the MFD power control I/O  244  via line  278 . The MFD power control line  248  is an open collector line so that each MFD  204  and  206  connected to the Ethernet cable  202  can connect and activate the MFD power control line  248  without bus contention. 
   The MFD power control I/O  244  holds the MFD power control line  248  low for a first predefined period of time and then allows the MFD power control line  248  to go open. By way of example only, the MFD power control line  248  may be held low for 2 seconds to superimpose the control signal over the Ethernet cable  202 . 
   The MFD power control I/O  246  of MFD  206  is connected to the power supply circuitry  256  via line  280  and the microprocessor  254  via line  282 . The low control signal on the MFD power control line  248  activates the power supply circuitry  256  to initiate a power up sequence. If the MFD power control line  248  is held low for a period of time outside the tolerance of the first predefined period of time, the power supply circuitry  256  may not initiate the power up sequence. By way of example only, the power supply circuitry  256  may have a requirement to sense a low control signal on the MFD power control line  248  of at least 0.75 seconds prior to initiating the power up sequence. 
   As the microprocessors  250  and  254  sense the MFD power control line  248  via MFD power control I/O  244  and  246 , respectively, the MFDs  204  and  206  can identify whether the power change sequence has been initiated at the same MFD or remotely, from a different MFD. If the MFD, such as MFD  206 , senses that another MFD, such as MFD  204 , has initiated the power change sequence, the MFD  206  will power on and the microprocessor  254  will maintain the display  228  in an off state, such as in a sleep mode. Therefore, the MFD  206  will be accessing and/or receiving available information, such as weather data and GPS data collected from the sensors  208  and  210 , in addition to waypoints and other information entered on other MFDs. The information will be available to a user immediately if the user wishes to power on the display  228  and access the data from the MFD  206 . In addition, a power savings is realized by not powering on the display  228  when the display  228  is not needed. 
   While the network  200  is in the powered on state, the microprocessors  250  and  254  continue to monitor the switches  212  and  214 , respectively. If the switch  212  of MFD  204  is activated, the microprocessor  250  displays a message on the display  226 , as discussed previously. If the user selects the option to turn the display  226  off, the power is removed from the backlight (not shown) of the display  226  while the MFD  204  remains in a power on state. The power state of the other MFDs and sensors connected to the Ethernet cable  202  remains the same, or in the power on state. 
   Similarly, if the network  200  is in the powered on state and one or more of the displays  226  and  228  are powered off, the microprocessors  250  and  254  continue to monitor the switches  212  and  214 . When the switch  212  or  214  is activated, the microprocessor  250  or  254  initiates the power to be immediately restored to the associated display  226  or  228 . There is no need to wait for the components of the network  200  to power up and gather information. 
   Therefore, a user has the capability of turning the displays  226  and  228  on and off as needed as the user moves to different areas of the marine craft, but does not lose the information which has been gathered by the sensors  208  and  210 , or additional data or waypoints which have been entered at one or more MFDs  208  and  210 . Therefore, it should be understood that while the network  200  is in the powered on state, one, more than one, or no displays  226  and  228  may be powered on. By being able to turn the displays  226  and  228  off individually, a significant power savings can be realized without the inconvenience of losing acquired and entered data. 
   The network  200  may be turned off from any MFD  204  and  206  connected to the Ethernet cable  202 . As discussed previously, the microprocessors  250  and  254  continue to monitor the switches  212  and  214 , respectively, while the network  200  is in the powered on state. When the switch  212  of MFD  204  is activated, the microprocessor  250  displays a message on the display  226 , as discussed previously. If the user selects the option to turn the network  200  off, the microprocessor  250  initiates a power down sequence to change the MFD  204  to be in a power off state. As discussed previously with  FIGS. 1 and 2 , the microprocessor  250  sends a control signal to the sensor power control output  234  via line  270  and releases the sensor power control line  242 . The power supply circuitry  258  and  260  and/or microprocessors  262  and  264  of the sensors  208  and  210  sense the change in the sensor power control line  242  at sensor power control inputs  238  and  240 , and initiate a power down sequence to change each of the sensors  208  and  210  to be in a power off state. Therefore, there is no need for the user to turn each of the sensors  208  and  210  off individually, or to wonder whether any sensor was left on by mistake. 
   The microprocessor  250  sends a control signal to the MFD power control I/O  244  via line  278 , and the MFD power control I/O  244  holds the MFD power control line  248  low for a second predefined period of time, which is different with respect to the first predefined period of time. The microprocessor  250  then allows the MFD power control line  248  to go open. By way of example only, the MFD power control line  248  may be held low for 0.25 seconds. 
   The microprocessor  254  and/or power supply  256  of MFD  206  monitors the MFD power control I/O  246 . When a low control signal is sensed for the second predefined period of time, or within a range based on the second predefined period of time, at the MFD power control I/O  246 , the microprocessor  254  of the MFD  206  initiates a power down sequence. For example, when the microprocessor  254  senses a low control signal within a range of 0.1-0.4 seconds on the MFD power control line  248 , the microprocessor  254  will initiate the power down sequence. If the microprocessor  254  senses a low control signal on the MFD power control line  248  lasting less than 0.1 second or longer than 0.4 seconds, the power down sequence is not initiated. Thus, the user does not have to turn each MFD  204  and  206  off individually, but can remotely control the power state of each MFD  204  and  206  from whichever MFD unit is convenient. 
   If an MFD is in a power state different from the rest of the network  200 , the MFD may be brought into synchronization when the power state of the network  200  is changed. For example, MFD  206  is in a power off state while MFD  204  and sensors  208  and  210  are in a power on state. If the switch  214  of MFD  206  is activated, the microprocessor  254  outputs control signals to the sensor power control line  242  and the MFD power control line  248  to initiate a power up sequence in the sensors  208  and  210  and the MFD  204 . The sensor power control line  242  is already being held low by the MFD  204  which is powered on. The microprocessor  250  of the MFD  204  receives the control signal on the MFD power control I/O  244 , which is the low control signal held for the first predefined period of time. The microprocessor  250  does not initiate any action to change the power state of MFD  204  as the MFD  204  is already in the power on state. 
   Therefore, all of the devices connected to the Ethernet cable  202  can be remotely turned on and off at one time from one location, preventing a device from being unintentionally left in the powered on state, which may completely discharge the battery. In other words, the power may be removed from the network  200  by activating the power switch of any MFD connected to the Ethernet cable  202 , then choosing the appropriate option on the display. 
   While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.