Abstract:
A power reception apparatus receives feed information from a predetermined line of a communication cable and judges a state of the power reception apparatus. If the state is normal, it transmits the feed information by returning it to a line which is a pair with the predetermined line.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. application Ser. No. 11/462,146, filed on Aug. 3, 2006, which is now pending and claims priority to Japanese Patent Application No. 2006-083859. The entire contents of each of these applications is hereby incorporated by reference. 
    
    
     FIELD 
     The present invention relates to a feed line monitor apparatus and a related program for such a local area network (LAN) system applied by a standard specification IEEE802.3af. 
     BACKGROUND 
     In recent years, the American Institute of Electrical and Electronics Engineers has proposed a standard by the name of IEEE802.3af. This is a standard for a circuit equipping a feed circuit on the conventional signal transmission circuit, which is a standard for feeding also an electric power through a signal line, such as a LAN cable, for transmitting and receiving signals. 
       FIG. 1  is a diagram showing an eight-line LAN cable  1 , for use in the standard, which is connected to a connector  2  (e.g., RJ45 type connector  2 ), where the pin numbers “ 1 ,  2 ,  3  and  6 ” are used for a data transmission and also for feeding power. When feeding, the pin numbers “ 1  and  2 ” are used for applying a voltage up to 48 volts, while the pin numbers “ 3  and  6 ” are used for a ground (GND) voltage. 
     Meanwhile, the pin numbers “ 4 ,  5 ,  7  and  8 ” are spared, except for the case of using them for a data transmission and feeding power. 
       FIG. 2  is a diagram showing a system utilizing the above noted LAN cable  1 . A communication apparatus A communicates with a communication apparatus B and also feeds power thereto. Taking the communication apparatus A as a feed apparatus  3  and the communication apparatus B as a power reception apparatus  4 , the power reception apparatus  4  for use as per the IEEE802.3af commonly comprises a incoming circuit  4 - 1 , a PHY  4 - 2  and a field programmable array gate array (FPGA)  4 - 3  as shown in  FIG. 3 . 
     The incoming circuit  4 - 1  is a circuit for receiving a power supplied from a feed apparatus. 
     The PHY  4 - 2  is a circuit for converting a data format handled by a physical layer of an OSI layer model into a data format which is handled by a data link layer. The OSI layer model is a hierarchical layer structure model for a communication function based on the Open Systems Interconnection (OSI) which is a design policy of a network structure established by the International Organization for Standardization (ISO). 
     The FPGA  4 - 3 , being an integrated circuit allowing a change of operations of a logic circuit, is for carrying out data process at the power reception apparatus  4 . 
     In a communication apparatus compliant to the IEEE802.3 Standard supporting a communication and a feed by a single communication cable, the already known is a technique of a complex electric circuit and a highly integrated circuit, e.g., a technique for communication to transmit contact information of the communication apparatus and communication cable to an opposite apparatus with the above noted PHY, FPGA.
     [Patent document 1] Laid-Open Japanese Patent Application Publication No. 2000-244373   

     The conventional technique is actually useful for a transmission using a communication apparatus which carries out a high level communication. However, when considering a relay as a communication apparatus for example, a PHY or an FPGA has been equipped with the communication apparatus which is used as the relay even in the case of only monitoring an abnormality of the relay. That is, in the case of communicating between the first and second communication apparatuses by using a relay, a complex PHY or FPGA has been required for establishing a connection between the relay and a third communication apparatus even when detecting a presence or absence of an abnormality of the relay by the third communication apparatus equipped with a feed function, which is connected to the relay of a feed voltage of an equipment connected to the relay. Equipping a using equipment with these apparatuses levies a large load in terms of design period, evaluation period, cost, et cetera, thus requiring a simple apparatus instead. 
     SUMMARY 
     Accordingly in consideration of the above described situation, the present invention is to provide an apparatus for accomplishing an establishment, when it is required, of a physical connection which is controlled in a physical layer without using an apparatus such as a PHY or an FPGA. 
     A first embodiment of the present invention provides a feed control program comprising the steps of detecting an existence of a power reception side and transmitting a link signal thereto by transmitting a voltage thereto; judging whether or not a power reception apparatus is normal by a presence or absence of a return to the link signal back to a feed side from the reception side; and the step of continuing a feed if the reception apparatus is normal and stopping the feed if it is not normal. 
     This comprisal makes it possible to judge a possibility of continuing a feed to a power reception apparatus by a simple configuration. 
     A second embodiment of the present invention provides a power reception control program, comprising the steps of receiving a signal from a feed side by way of a first transmission path; transmitting a signal to a feed side by way of a second transmission path; and controlling a changeover unit so as to make said reception signal as a transmission signal by returning it if a power reception side is normal and not to return the reception signal as the transmission signal if the power reception side is abnormal. 
     This comprisal makes it possible to notify a feed apparatus of an abnormality of a power reception apparatus by a simple configuration. 
     A third embodiment of the present invention provides a relay, being an apparatus for relaying a signal from a first communication apparatus to a second communication apparatus, comprising: a unit for receiving a signal from a third communication apparatus side by way of a first transmission path; a unit for transmitting a signal to the third communication apparatus side by way of a second transmission path; a power reception apparatus comprising a first changeover unit for controlling so as to make said reception signal as a transmission signal by returning it if the relay is normal and not to return the reception signal as the transmission signal if the relay is abnormal; and a second changeover unit for carrying out a communication between the first or second communication apparatuses and the third communication apparatus if the relay is normal, and changing a signal transmission from the first communication apparatus over to the second communication apparatus if the relay is abnormal. 
     This comprisal enables to notify of an abnormality of a relay and also carry out a fail safe operation by a simple configuration. 
     The present invention is contrived to enable a discernment of a presence or absence of an abnormality of a power reception apparatus by a simple configuration without using an apparatus such as PHY and FPGA as system which performed data communication by way of feed line. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram showing an eight-line LAN cable for use as standard for the IEEE802.3af; 
         FIG. 2  is a diagram exemplifying an embodiment of a system utilizing a LAN cable; 
         FIG. 3  is a diagram showing a conventional power reception apparatus; 
         FIG. 4  is a block diagram showing a configuration of a power reception apparatus according to the present invention; 
         FIG. 5A  is a flow chart showing a process on a feed apparatus side; 
         FIG. 5B  is a flow chart showing a process on a power reception side; 
         FIG. 6  is a diagram showing a monitoring method, by a monitor apparatus, for a voltage value applied to a main circuit from a feed circuit; 
         FIG. 7  is a diagram showing a method for monitoring a voltage value at a specific device within a main circuit; and 
         FIG. 8  is a block diagram of a system using a power reception apparatus according to the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following is a description of the preferred embodiment of the present invention by referring to the accompanying drawings. 
       FIG. 4  is a block diagram showing a configuration of a power reception apparatus according to the present invention. The power reception apparatus  40  comprises a connector  2 , a transformer  5 , electromagnetic relays  6 - 1  and  6 - 2 , and a main circuit  7 . 
     A “number  1  line” connected to the pin number “ 1 ” of the connector  2  is connected to an input contact (not shown herein) of the electromagnetic relay  6 - 1  by way of the transformer  5 . An “output line  1 ” connected to an output contact of the electromagnetic relay  6 - 1  is connected to the pin number “ 3 ” of the connector  2  by way of the transformer  5 . 
     A “number  2  line” connected to the pin number “ 2 ” of the connector  2  is connected to an input contact (not shown herein) of the electromagnetic relay  6 - 2  by way of the transformer  5 . An “output line  2 ” connected to an output contact of the electromagnetic relay  6 - 2  is connected to the pin number “ 6 ” of the connector  2  by way of the transformer  5 . 
     The transformer  5  is an apparatus for shutting off a DC voltage, that is, a feed voltage and transmitting an AC voltage, that is, a signal component. 
     If the power reception apparatus  40  is in a normal operating state, the contacts of the electromagnetic relays  6 - 1  and  6 - 2  close, making a link pulse a connected state between the pin numbers “ 1  and  3 ”, and between the pin numbers “ 2  and  6 ”. The link pulse received from a feed apparatus  3  by way of the line  1  and line  2  of a transmission path  1  comprising a LAN cable is turned back at the electromagnetic relays  6 - 1  and  6 - 2 , followed by being transmitted to the feed apparatus  3  by way of the lines  3  and  6  of the transmission path  1 . 
     The main circuit  7  comprises an incoming circuit  8  (e.g., a power reception circuit), a control circuit  9  and a monitor apparatus  10 . 
     The incoming circuit  8  is a circuit for supplying the control circuit  9 , monitor apparatus  10 , et cetera, with power by converting into respectively appropriate voltages based on the power fed between the pin numbers “ 1  and  2 ”, and between the pin numbers “ 3  and  6 ”, of the connector  2 . 
     The monitor circuit  10  is a circuit for monitoring a state of the power reception apparatus  4 , particularly of the control circuit  9  of the main circuit  7 . 
     The following is a description of operations of the feed apparatus and power reception apparatus by referring to the flow charts shown by  FIGS. 5A and 5B . The first description is of the flow chart of  FIG. 5A  showing a process of the feed apparatus. 
     According to the standard of the IEEE802.3af, the feed apparatus  3  validates an operation of the power reception apparatus  4  (ST 1 ) and detects a class thereof (ST 2 ). The validation of an operation is performed by detecting a current by applying a voltage to a termination resistor. The detection of a class is performed by applying voltages in a certain range in a certain range of time and selecting a class by categorizing the maximum power consumption of the power reception apparatus based on the currents. Having detected a class of the power reception apparatus  4 , the power suitable to the class is supplied. 
     Then, the feed apparatus  3  confirms that the connected power reception apparatus  40  is normal, or not (ST 3 ). A method for confirming the power reception apparatus  40  is normal is to utilize a validation signal called a link pulse which has been transmitted from the pin numbers “ 1  and  2 ” of the connector  2  of the feed apparatus  3 . In this event, the conventional power reception apparatus  4  equipped with a PHY would have received a link pulse transmitted from a feed apparatus and also would have transmitted a response signal from the pin numbers “ 3  and  6 ” of the connector  2 . Contrarily, the present invention is configured to not comprise a PHY, and therefore is not able to transmit a response signal to the feed apparatus. The feed apparatus has already recognized a use of the power reception apparatus  40  unequipped with a PHY. The present invention is configured to validate a normality of the power reception apparatus by detecting a return of the transmitted link pulse by way of the electromagnetic relays  6 - 1  and  6 - 2 . 
     If the power reception apparatus  40  is operating normally (“normal” in ST 3 ), the contacts of the electromagnetic relays  6 - 1  and  6 - 2  are closed, and therefore the link pulse transmitted from the feed apparatus  3  is returned by way of the electromagnetic relays  6 - 1  and  6 - 2 . Having detected the returned link pulse (ST 4 ), judging that the power reception apparatus  4  is normal, the feed apparatus  3  accordingly continues the feed (ST 5 ). 
     If the power reception apparatus  4  is operating abnormally (“abnormal” in ST 2 ), the contacts of the electromagnetic relays  6 - 1  and  6 - 2  are open and the link pulse is not returned, and the feed apparatus stops the feed by judging an abnormality (ST 6 ). 
     The next is a description of the flow chart of a process over at the power reception apparatus  40  with reference to  FIG. 5 . 
     Having been fed from the feed apparatus (ST 7 ), the power reception apparatus  40  closes the contacts of electromagnetic relays  6 - 1  and  6 - 2  (ST 9 ), if the apparatus per se is operating normally (“normal” in ST 8 ). Contrarily, if the apparatus per se is operating abnormally (“abnormal” in ST 8 ), the power reception apparatus  40  opens the contacts of the electromagnetic relays  6 - 1  and  6 - 2  (ST 10 ). 
     The execution of the above described process establishes a connection of the power reception apparatus to the feed apparatus. Note that the above description is of the case of feeding by using the pin numbers “ 1 ,  2 ,  3  and  6 ” of the connector  2 , it is, however, possible to accomplish likewise the case of feeding by using the pin numbers “ 4 ,  5 ,  7  and  8 ”. In such a case, the feed circuit  8  is connected to the pin numbers “ 4 ,  5 ,  7  and  8 ”. 
     The following is a description of a concrete embodiment of a monitor method. 
     As shown by  FIG. 6 , the monitor apparatus  10  monitors a voltage value applied to the control circuit  9  from a power supply. If the voltage value is equal to or greater than a certain threshold value (e.g., 3.3 volts), the control circuit  9  is judged to be normal. Contrarily, if it is less than a threshold value (e.g., 1.7 volts) as a result of a failure occurrence, the control circuit  9  is judged to be abnormal. An output of the monitor apparatus  10  is sent to the electromagnetic relays  6 - 1  and  6 - 2  shown in  FIG. 4  and used for an open/close changeover operation thereof. 
     As shown by  FIG. 7 , there is another method for monitoring a voltage value in the inside, or an output of, a specific device within a control circuit as another embodiment. If the voltage value greater than a certain original value (e.g., A volts), the control circuit  9  is judged to be normal. However, if a failure occurs, causing a value to be lower that the original value (e.g., 0 volt), it is judged to be abnormal. 
     The next description is of a concrete embodiment at the time of using the power reception apparatus  40  according to the present invention.  FIG. 8  shows a block chart of the system. The power reception apparatus  40  according to the present invention is equipped in the inside of a relay  12  that is a changeover apparatus performing an Add/Drop operation. The relay  12  relays a communication between apparatuses C and D. 
     A communication apparatus A is connected to the relay  12  by way of a communication path and an eight-line LAN cable  1 . 
     The communication apparatus A is a feed apparatus, and the relay  12  is equipped with a power reception apparatus  40  which is equivalent to a communication apparatus B. 
     As the communication apparatus A is connected to the power reception apparatus  40  within the relay  12  by the process of the flow chart described for  FIGS. 5A and 5B , a data communication between the communication apparatuses C and D enables the communication apparatus A to operate an Add/Drop by way of relay  12 . 
     However, if a certain failure occurs in the relay  12 , a feed thereto from the LAN cable  1  stops. As the feed stops, the electromagnetic relays  6 - 1  and  6 - 2  of the power reception apparatus  40  open, thereby interrupting a feed from the communication apparatus A to the power reception apparatus  40 , opening a contact of a first electromagnetic relay (not shown herein) of a switch  13  and shutting off a communication between the relay  12  and communication apparatus A (stopping an Add/Drop operation). 
     In this event, the switch  13  of the relay  12  changes over to a direction so as to close a contact of a second electromagnetic relay (not shown herein) and also secure a communication between the communication apparatuses C and D. That is, to result in opening the contact for the relay  12  communicating with the communication apparatus A, while closing the contact for connecting the communication apparatus C with the D in the switch  13 . 
     As such, the relay  12  is used for a fail safe for the communication apparatuses C and D. 
     While the embodiment applying the present invention has so far been described, the present invention can adopt various configurations possible within the scope thereof, in lieu of being limited by the above described embodiment.