Electronic device, method for cooling an electronic device, and controlled unit

Abstract

To appropriately maintain a cooling function while suppressing the number of connector wires.SOLUTION: An apparatus according to one aspect of the present disclosure is an electronic apparatus including a backplane, one control unit being a monitoring main body mountable on the backplane, and a plurality of units to be controlled being monitoring objects mountable on the backplane. The backplane includes a monitoring communication wire for inter-unit communication between the control unit and the plurality of units to be controlled, and a bus connection type alternative control wire. The plurality of units to be controlled include a first unit being a high temperature prevention object and a second unit for driving a cooling fan. The first unit executes alternative control to operate the second unit by using the alternative control wire instead of the control unit with communication interruption of the control unit as an opportunity.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to an electronic device, a method for cooling an electronic device, and a controlled unit.

Background Art

[0002] Patent Document 1 describes a technique for reducing the number of signal lines on a backboard to which a plurality of circuit boards are connected by mounting alarm signals with different timings on the signal lines connected by a bus. Patent Document 2 describes a technique in a storage system including a cooling device for cooling the inside of a housing and a plurality of control units, in which each control unit determines a temporary control unit responsible for controlling the cooling device based on the mounting state of the control unit and the operating state of the cooling device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Documents 1 and 2, in an electronic device having only one control unit as a monitoring entity, a measure for appropriately maintaining the cooling function while suppressing the number of wirings of the connector to the backplane is not assumed. In view of such conventional problems, an object of the present disclosure is to appropriately maintain the cooling function while suppressing the number of wirings of the connector.

Means for Solving the Problems

[0005] An electronic device according to one aspect of the present disclosure comprises a backplane, a control unit which is a monitoring entity that can be mounted on the backplane, and a plurality of controlled units which are monitoring targets that can be mounted on the backplane, wherein the backplane includes a monitoring communication line for unit-to-unit communication between the control unit and the plurality of controlled units, and a bus-connected alternative control line, and the plurality of controlled units include a first unit which is a high-temperature prevention target and a second unit which drives a cooling fan, and the first unit performs substitute control to operate the second unit using the alternative control line in place of the control unit when communication with the control unit is interrupted.

[0006] A method according to one aspect of the present disclosure is a method for cooling an electronic device comprising a backplane, a control unit mounted on the backplane which is a monitoring entity, and a plurality of controlled units mounted on the backplane which are objects to be monitored, wherein the backplane includes a monitoring communication line for unit-to-unit communication between the control unit and the plurality of controlled units, and a bus-connected alternative control line, and the plurality of controlled units include a first unit which is an object to be prevented from overheating and a second unit which drives a cooling fan, and the cooling method includes the steps of the first unit monitoring the status of the control unit and the first unit performing substitute control to operate the second unit using the alternative control line in place of the control unit when communication with the control unit is interrupted.

[0007] An apparatus according to another aspect of the present disclosure is a controlled unit to be monitored, which can be mounted on a backplane that includes a monitoring communication line for inter-unit communication and a bus-connected alternative control line, and comprises a circuit board having a connector mounted on the backplane, and a signal processing unit mounted on the circuit board, wherein the signal processing unit sends a signal to the alternative control line to drive a cooling fan of another controlled unit when a communication interruption occurs in the control unit that is the monitoring entity.

[0008] An apparatus according to another aspect of the present disclosure is a controlled unit to be monitored, which can be mounted on a backplane including a monitoring communication line for inter-unit communication and a bus-connected alternative control line, comprising: a circuit board having a connector mounted on the backplane; a signal processing unit mounted on the circuit board; and a cooling fan mounted on the circuit board, wherein the signal processing unit drives the cooling fan based on a signal sent by another controlled unit to the alternative control line in the event of a communication failure of the monitoring control unit.

[0009] This disclosure can be implemented not only as a system and apparatus having the characteristic configuration described above, but also as a program for causing a computer to execute such characteristic configuration. Furthermore, this disclosure can be implemented as a semiconductor integrated circuit that implements part or all of the system and apparatus. [Effects of the Invention]

[0010] According to this disclosure, it is possible to maintain proper cooling functionality while reducing the number of wires in the connector. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a perspective view showing an example of the internal structure of a communication device. [Figure 2] Figure 2 is a block diagram showing an example of the circuit configuration of a communication device. [Figure 3] Figure 3 is an explanatory diagram showing an example of a connection configuration for inter-unit communication. [Figure 4] Figure 4 is an explanatory diagram showing another example of a connection configuration for inter-unit communication. [Figure 5] Figure 5 is an explanatory diagram showing an embodiment of communication control 1. [Figure 6] Figure 6 is an explanatory diagram showing an embodiment of communication control 1. [Figure 7] Figure 7 is an explanatory diagram showing an embodiment of communication control 2. [Figure 8] Figure 8 is an explanatory diagram showing an embodiment of communication control 3. [Figure 9] FIG. 9 is an explanatory diagram showing an embodiment of communication control 4. [Figure 10] FIG. 10 is a sequence diagram showing an example of periodic state monitoring. [Figure 11] FIG. 11 is a sequence diagram showing an example of state monitoring when an event occurs. [Figure 12] FIG. 12 is a flowchart showing an example of state monitoring control. [Figure 13] FIG. 13 is an explanatory diagram showing Example 1 of proxy control 1. [Figure 14] FIG. 14 is an explanatory diagram showing Example 2 of proxy control 1. [Figure 15] FIG. 15 is a block diagram showing an embodiment of proxy control 2.

Mode for Carrying Out the Invention

[0012] <Summary of Embodiments of the Present Disclosure> The following lists and describes the summary of the embodiments of the present disclosure. (1) The device according to this embodiment is an electronic device including a backplane, one control unit which is a monitoring subject attachable to the backplane, and a plurality of controlled units which are monitoring objects attachable to the backplane. The backplane includes a monitoring communication line for unit - to - unit communication between the control unit and the plurality of controlled units, and a bus - connected alternative control line. The plurality of controlled units include a first unit which is a high - temperature prevention target and a second unit which drives a cooling fan. When communication of the control unit is interrupted, the first unit executes proxy control to operate the second unit using the alternative control line instead of the control unit.

[0013] According to the electronic device of this embodiment, since the first unit executes the above - mentioned proxy control when communication of the control unit is interrupted, it is possible to realize driving of the cooling fan when the control unit is removed or malfunctions occur without increasing the monitoring communication line. Therefore, it is possible to appropriately maintain the cooling function while suppressing the number of connector wirings.

[0014] (2) In the electronic device of this embodiment, the alternative control line is such that the outputs of the single or plural first units are wired-logically connected. If the output of at least one of the first units is ON, the Alternative control line value becomes asserted, and can be the substitute control may include a process in which the first unit keeps the output to the alternative control line OFF during communication establishment of the control unit and turns the output to the alternative control line ON during communication interruption of the control unit.

[0015] In this way, by the first unit outputting an ON signal or an OFF signal to the alternative control line, the control type of the fan control to be executed by the second unit can be switched.

[0016] (3) In the electronic device of this embodiment, the first unit and the second unit are bus-connected by the alternative control line. The substitute control may include a process in which the second unit controls the fan rotation speed according to the control information received from the control unit when the value of the alternative control line is negative, and sets the fan rotation speed to a predetermined value when the value of the alternative control line is asserted.

[0017] In this way, since the second unit sets the fan rotation speed to a predetermined value when the value of the alternative control line is asserted (when the control unit has a communication interruption), the cooling fan can be driven even if the control unit is removed or malfunctions.

[0018] (4) In the electronic device of this embodiment, the plurality of controlled units include a third unit which is a relay node between the control unit and the second unit, the first unit and the third unit are bus-connected by the alternative control line, and the substitute control may include the process by which the third unit transmits control information received from the control unit to the second unit if the value of the alternative control line is negated, and transmits control information to the second unit which sets the fan speed to a predetermined value if the value of the alternative control line is asserted.

[0019] In this way, the third unit sends control information to the second unit to set the fan speed to a predetermined value when the value of the alternative control line is asserted (i.e., the control unit has lost communication), so the cooling fan can be driven even if the control unit is removed or malfunctions occur.

[0020] (5) In the electronic device of this embodiment, the first unit and the second unit are bus-connected by the alternative control line, and the alternative control may include the first unit and the second unit performing clock synchronization while the control unit is establishing communication, and the first unit converting the output to the alternative control line to a PWM signal when the control unit is not communicating.

[0021] In this way, the first and second units synchronize their clocks while the control unit is establishing communication, and the first unit outputs a PWM signal to the alternative control line when the control unit's communication is interrupted. Therefore, even if the control unit is removed or malfunctions, the cooling fan can still be driven.

[0022] (6) In the electronic device of this embodiment, the control unit is bus-connected by the alternative control line and is capable of generating a PWM signal on the alternative control line, and the first unit and the second unit may perform clock synchronization using the PWM signal generated by the control unit.

[0023] In this way, the first and second units synchronize their clocks using the PWM signal originating from the control unit, thus enabling accurate clock synchronization between the units.

[0024] (7) The method according to this embodiment is a cooling method performed in the electronic devices described in (1) to (6) above. Therefore, the cooling method of this embodiment has the same effects as the electronic devices described in (1) to (6) above.

[0025] (8) Another apparatus according to this embodiment is a controlled unit to be monitored, which can be mounted on a backplane that includes a monitoring communication line for inter-unit communication and a bus-connected alternative control line, and comprises a circuit board having a connector mounted on the backplane, and a signal processing unit mounted on the circuit board, wherein the signal processing unit sends a signal (e.g., an alternative control signal or a PWM signal) to the alternative control line to drive a cooling fan of another controlled unit when the communication of the monitoring control unit is interrupted.

[0026] According to the controlled unit (e.g., line unit) of this embodiment, the signal processing unit sends a signal to an alternative control line to drive the cooling fan of another controlled unit (e.g., fan unit). Therefore, the cooling fan can be driven when the control unit is disconnected or malfunctions occur without increasing the number of monitoring communication lines. Accordingly, the cooling function can be properly maintained while suppressing the number of connector wires.

[0027] (9) Another apparatus according to this embodiment is a controlled unit to be monitored, which can be mounted on a backplane including a monitoring communication line for inter-unit communication and a bus-connected alternative control line, comprising a circuit board having a connector mounted on the backplane, a signal processing unit mounted on the circuit board, and a cooling fan mounted on the circuit board, wherein the signal processing unit drives the cooling fan based on a signal (e.g., an alternative control signal or a PWM signal) generated by another controlled unit on the alternative control line when a communication interruption occurs in the control unit that is the monitoring entity.

[0028] According to the controlled unit (e.g., fan unit) of this embodiment, the signal processing unit drives the cooling fan based on a signal generated by another controlled unit (e.g., line unit) on an alternative control line. Therefore, the cooling fan can be driven when the control unit is disconnected or malfunctions occur without increasing the number of monitoring communication lines. Accordingly, the cooling function can be properly maintained while suppressing the number of connector wires.

[0029] <Details of the embodiments of this disclosure> The embodiments of this disclosure will be described in detail below with reference to the drawings. At least some of the embodiments described below may be combined in any way.

[0030] [Example of a communication device structure] Figure 1 is a perspective view showing an example of the internal structure of communication device 1. Figure 2 is a block diagram showing an example of the circuit configuration of communication device 1. The communication device 1 of this embodiment is an example of an electronic device of the present disclosure and consists of a hot-swapping communication device. As shown in Figures 1 and 2, the communication device 1 comprises a housing 2, a backplane 3, a control unit 4, a line unit 5, a power supply unit 6, and a fan unit 7.

[0031] Enclosure 2 is, for example, a 1U-sized metal casing. Enclosure 2 has a front opening 21 and a rear opening 22 through which units 4, 5, 6, and 7 can be inserted and removed. A backplane 3 is incorporated inside the enclosure 2. The backplane 3 is a circuit board that is long in the left-right direction and has almost the same shape as the cross-section of the enclosure 2. The backplane 3 is located almost in the center in the front-to-back direction inside the enclosure 2 and acts as a wall that divides the enclosure 2's housing space into roughly two halves in the front-to-back direction.

[0032] The backplane 3 has a plurality of connectors 31 for inter-unit communication. The connectors 31 are, for example, female type. The backplane 3 has a plurality of vents 32 for circulating cooling air from the fan in the front-to-back direction. In the example diagram, five connectors 31 are arranged in a single row horizontally on the front of the backplane 3. Although hidden in Figure 1, five connectors 31 are also arranged in a single row horizontally on the back of the backplane 3. Note that the number of connectors 31 installed on the backplane 3 is not limited to 10 and can be designed arbitrarily.

[0033] The communication device 1 is a unit that can be connected to the connector 31 of the backplane 3 and comprises a control unit 4, which is the main monitoring unit for status monitoring via inter-unit communication, and a plurality of controlled units 5, 6, and 7 that are the targets of monitoring. In other words, the control unit 4 is a unit that monitors the status of the other units 5, 6, and 7 mounted on the backplane 3, and the line unit 5, power supply unit 6, and fan unit 7 are the units that the control unit 4 monitors.

[0034] The communication standard for inter-unit communication is not particularly limited as long as it enables digital communication, but for example, HDLC (High-Level Data Link Control), I2C, Ethernet, etc. can be used. In this embodiment, HDLC will be used.

[0035] In the structural example shown in Figure 1, one control unit 4 and three line units 5 are mounted on the front side of the backplane 3, and two power supply units 6 and three fan units 7 are mounted on the rear side of the backplane 3. However, the number of each unit 4, 5, 6, and 7 installed is not particularly limited. However, since the power supply unit 6 is a unit that supplies power to the communication device 1, at least one power supply unit 6 must always be installed on the backplane 3 in order to maintain the operation of the device.

[0036] [Internal configuration of the control unit] As shown in Figure 2, the control unit 4 comprises a circuit board 40 and a connector 41 provided on the edge of the circuit board 40. The connector 41 is, for example, a male connector that can be attached to and detached from the connector 31 of the backplane 3. The control unit 4 may also include a housing that covers the circuit board 40.

[0037] The control unit 4 comprises a signal processing unit 42, a CPU (Central Processing Unit) 43, a memory 44, a communication processing unit 45, a management port 46, and a power supply unit 47 as electronic components mounted on a circuit board 40. These electronic components are electrically connected by the wiring patterns of the circuit board 40 shown by solid lines in Figure 2.

[0038] The signal processing unit 42 is an electronic circuit that includes, for example, an FPGA (Field-Programmable Gate Array). The FPGA is configured with a signal processing circuit for inter-unit communication that conforms to a predetermined communication standard such as HDLC. The CPU 43 is an arithmetic processing unit that comprehensively controls the operation of the control unit 4. For example, the CPU 43 makes setting changes to the signal processing unit 42, the communication processing unit 45, etc., based on predetermined setting information recorded in the memory 44.

[0039] The communication processing unit 45 is, for example, a MAC (Media Access Control) chip. The management port 46 is, for example, an RJ-45 connector. A management computer owned by the communications administrator, or a router connected to the internet, is connected to the management port 46. The communication processing unit 45 is connected not only to its own unit's CPU 43 but also to the CPU 53 of the line unit 5 via a management signal line 33. The communication processing unit 45 receives Ethernet frames ("Ethernet" is a registered trademark) containing management information from the management computer.

[0040] If the management information contained in the received frame is the configuration information of its own unit, the communication processing unit 45 transmits the configuration information to the CPU 43 of its own unit. The CPU 43 records the received configuration information in the memory 44. If the management information contained in the received frame is the configuration information of the line unit 5, the communication processing unit 45 transmits the configuration information to the CPU 53 of the line unit 5. The CPU 53 records the received configuration information in the memory 54.

[0041] The power supply unit 47 is, for example, an electronic circuit including a DC / DC converter. The DC / DC converter converts the DC voltage of the DC distribution line 34 to a predetermined voltage and supplies the converted DC voltage to an electronic circuit including active elements mounted on the circuit board 40.

[0042] [Internal configuration of the line unit] As shown in Figure 2, the line unit 5 comprises a circuit board 50 and a connector 51 provided on the edge of the circuit board 50. The connector 51 is, for example, a male connector that can be attached to and detached from the connector 31 of the backplane 3. The line unit 5 may also include a housing that covers the circuit board 50.

[0043] The line unit 5 includes a signal processing unit 52, a CPU 53, a memory 54, a switch unit 55, an external port 56, and a power supply unit 57 as electronic components mounted on the circuit board 50. These electronic components are electrically connected by the wiring pattern of the circuit board 50, which is shown by solid lines in Figure 2.

[0044] The signal processing unit 52 is an electronic circuit including, for example, an FPGA. The FPGA is configured with a signal processing circuit for inter-unit communication that conforms to a predetermined communication standard such as HDLC. The CPU 53 is a processing unit that comprehensively controls the operation of the line unit 5. For example, the CPU 53 makes setting changes to the signal processing unit 52, the switch unit 55, etc., based on predetermined setting information recorded in the memory 54.

[0045] The switch unit 55 is, for example, a high-speed Ethernet switch LSI (Large Scale Integration), such as a 10 Gigabit switch. The external port 56 consists of a connector that allows for the insertion and removal of, for example, a pluggable optical transceiver (not shown). The power supply unit 57 is, for example, an electronic circuit including a DC / DC converter. The DC / DC converter converts the DC voltage of the DC distribution line 34 to a predetermined voltage and supplies the converted DC voltage to an electronic circuit including active elements mounted on the circuit board 50.

[0046] [Internal configuration of the power supply unit] As shown in Figure 2, the power supply unit 6 comprises a circuit board 60 and a connector 61 provided on the edge of the circuit board 60. The connector 61 is, for example, a male connector that can be attached to and detached from the connector 31 of the backplane 3. The power supply unit 6 may also include a housing that covers the circuit board 60.

[0047] The power supply unit 6 includes a signal processing unit 62, a first voltage conversion unit 63, and a second voltage conversion unit 64 as electronic components mounted on the circuit board 60. These electronic components are electrically connected by the wiring pattern of the circuit board 60, which is shown by solid lines in Figure 2. The signal processing unit 62 is an electronic circuit including, for example, an FPGA. The FPGA is configured with a signal processing circuit for inter-unit communication that conforms to a predetermined communication standard such as HDLC.

[0048] The first voltage conversion unit 63 is an electronic circuit including, for example, an AC / DC converter. The first voltage conversion unit 63 converts an AC voltage supplied from a commercial power source or the like into a DC voltage of a predetermined voltage, and outputs the converted DC voltage to the DC distribution line 34 and the second voltage conversion unit 64. The second voltage conversion unit 64 is, for example, an electronic circuit including a DC / DC converter. The second voltage conversion unit 64 converts the DC voltage supplied from the first voltage conversion unit 63 into a DC voltage of a predetermined voltage and supplies the converted DC voltage to an electronic circuit including an active element mounted on the circuit board 60.

[0049] [Internal configuration of the fan unit] As shown in Figure 2, the fan unit 7 comprises a circuit board 70 and a connector 71 provided on the edge of the circuit board 70. The connector 71 is, for example, a male connector that can be attached to and detached from the connector 31 of the backplane 3. The fan unit 7 may also include a housing that covers the circuit board 70.

[0050] The fan unit 7 includes a signal processing unit 72, a cooling fan 73, and a power supply unit 74 as electronic components mounted on the circuit board 70. These electronic components are electrically connected by the wiring pattern of the circuit board 70, which is shown by solid lines in Figure 2. The signal processing unit 72 is an electronic circuit including, for example, an FPGA. The FPGA is configured with a signal processing circuit for inter-unit communication that conforms to a predetermined communication standard such as HDLC.

[0051] The cooling fan 73 is a fan whose airflow can be adjusted by controlling the rotation speed of an electric motor. The rotation speed of the cooling fan 73 is controlled by a control signal from the signal processing unit 72. The power supply unit 74 is an electronic circuit including, for example, a DC / DC converter. The DC / DC converter converts the DC voltage of the DC distribution line 34 to a predetermined voltage and supplies the converted DC voltage to the signal processing unit 72 and the electric motor of the cooling fan 73.

[0052] [Power supply unit relay function] As shown in Figure 2, the power supply unit 6 of this embodiment functions as a relay unit capable of relaying the second control signal among the following first and second control signals. First control signal: A control signal used for monitoring itself (power supply unit 6). Second control signal: A control signal used for monitoring controlled units other than itself (power supply unit 6) (here, fan unit 7 is used as an example).

[0053] In other words, the signal processing unit 62 of the power supply unit 6 is configured to perform signal processing that does not relay the first control signal but relays the second control signal to other units. Therefore, when the control unit 4, power supply unit 6, and fan unit 7 are mounted on the backplane, the inter-unit communication includes the following first and second communications.

[0054] First communication: The control unit 4 and the power supply unit 6 transmit and receive the first control signal without relaying. Second communication: The control unit 4 and the fan unit 7 transmit and receive the second control signal using the power supply unit 6 as a relay node.

[0055] [Backplane wiring structure] The printed circuitry on backplane 3 includes management signal lines 33, DC distribution lines 34, monitoring signal lines 35, and alternate control lines 36. Management signal lines 33 and monitoring signal lines 35 are connected one-to-one, while alternate control lines 36 are bus-connected. The management signal line 33 is a signal line for transmitting configuration information between CPUs 43 and 53. The monitoring signal line 35 is a signal line used by the control unit 4 for inter-unit communication to monitor the status of each unit 5, 6, and 7.

[0056] The wiring structure of the monitoring signal line 35 includes a wiring structure that assumes the three units 4, 6, and 7 perform the first and second communications described above. That is, the monitoring signal line 35 includes at least the following three types of signal lines. The alternative control line 36 is a signal line for wired logic connection of the outputs (voltage values) of one or more line units 7, and is, for example, an interrupt line. The logic configuration may be either positive logic or negative logic, but in this embodiment, the value when the output signal to the alternative control line 36 is ON is defined as asserted (enabled), and the value when it is OFF is defined as negated (disabled). As will be explained later, the alternative control line 36 can also output a PWM (Pulse Width Modulation) signal. In this case, when the duty cycle is an intermediate value between 0% and 100%, the output of the drive circuit (such as an open collector) switches between ON and OFF over time, and when the duty cycle is 0%, the output of the drive circuit is kept OFF. In this way, the alternative control line 36 can be used as both a transmission path for PWM signals and a transmission path for logical values.

[0057] 1st signal line 35A: At least two signal lines electrically connect the control unit 4 and the power supply unit 6. Second signal line 35B: At least two signal wires that electrically connect the power supply unit 6 and the fan unit 7. Third signal line 35C: At least two signal lines electrically connect the control unit 4 and the line unit 5.

[0058] Specifically, when the control unit 4, line unit 5, and power supply unit 6 are attached to the designated numbered connectors 31 on the backplane 3, the signal processing unit 42 of the control unit 4 and the signal processing unit 62 of the power supply unit 6 are connected by the first signal line 35A. Similarly, the signal processing unit 62 of the power supply unit 6 and the signal processing unit 72 of the fan unit 7 are connected by a second signal line 35B, and the signal processing unit 42 of the control unit 4 and the signal processing unit 52 of the line unit 5 are connected by a third signal line 35C.

[0059] Thus, if the control unit 4, power supply unit 6, and fan unit 7 perform the first and second communications described above, the connection configuration (topology) of these units 4, 6, and 7 can be such that the control unit 4 and power supply unit 6 are connected one-to-one, and the power supply unit 6 and fan unit 7 are connected one-to-one.

[0060] Note that in Figure 2, for the sake of illustration simplicity, the circuit configuration is shown as an example where there is one control unit 4, one line unit 5, one power supply unit 6, and one fan unit 7. Therefore, the number of first, second, and third signal lines 35A, 35B, and 35C that should be wired to the backplane 3 increases depending on the number of units that can be mounted on the backplane 3 (the number of connectors 31 that can be installed).

[0061] For example, if four connectors 31 for line units 5 are provided, that is, if up to four line units 5 can be connected to one control unit 4, the number of third signal lines 35C wired to the backplane 3 will be four times the number shown in the diagram (e.g., five lines). The same applies to the first and second signal lines 35A and 35B. The advantages of using the power supply unit 6 as a relay unit in this embodiment will be explained below with reference to Figures 3 and 4.

[0062] [Connection configuration for inter-unit communication] Figure 3 is an explanatory diagram showing an example of a connection configuration for inter-unit communication (hereinafter referred to as "Connection Configuration 1"). Figure 4 is an explanatory diagram showing another example of a connection configuration for inter-unit communication (hereinafter referred to as "Connection Configuration 2").

[0063] In Figures 3 and 4, "CT" refers to the control unit 4, "LN" to the line unit 5, "PW" to the power supply unit 6, and "FN" to the fan unit 7. The numbers following CT, LN, PW, and FN are identification numbers for the same type of unit, in cases where the same type of unit can be mounted on backplane 3.

[0064] Here, the control signals used for inter-unit communication include the following five types, and each control signal is transmitted over one signal line. Therefore, each arrow in Figure 3 includes at least five signal lines. 1) EXT: Insertion of the unit is complete (attachment to connector 31 is complete) 2) RDY: Activation status of your unit 3) RST: Restart request to the opponent's unit 4) TX: Data transmission 5) RX: Data reception

[0065] In hot-swappable / removable communication devices, the most common configuration is the star connection shown in Figure 3, where the CT is connected one-to-one with the monitored LN, PW, and FN. Therefore, in connection configuration 1, a backplane 3 with a wiring pattern that allows CT1 to connect to 7 units is required. In this case, the number of signal lines required for the connector 31 for the CT is 5 lines × 7 units = 35 lines. However, there are inherent constraints on the size of the backplane 3 that can be housed in, for example, a 1U enclosure 2.

[0066] Therefore, if the connector 31 for the CT becomes enlarged, a structural problem arises in which multiple connectors 31 cannot be placed in desired positions on the backplane 3 (for example, in positions where cooling air from the cooling fan 73 can easily circulate). In contrast, in connection configuration 2 of Figure 4, the PW has a relay function for the second control signal, so the CT and PW are connected by the upper first signal line 35A, and the PW and FN are connected by the lower second signal line 35B, employing a connection configuration in which the PW acts as a relay node.

[0067] In this case, CT1 should adopt a backplane 3 with a wiring pattern that allows it to connect to PW1, PW2, LN1, and LN2 respectively. Therefore, the number of signal lines required for the connector 31 for CT1 is 5 lines × 4 units = 20 lines, which is a significant reduction in the number of signal lines required for the connector 31 for CT1 compared to connection configuration 1 in Figure 3.

[0068] In this way, by connecting the CT and PW with the upper first signal line 35A, and connecting the PW and FN with the lower second signal line 35B, the number of signal lines in the connector 31 for the CT can be reduced. Therefore, compared to connection configuration 1, where LN, PW, and FN are all connected to the CT, the connector 31 for the CT can be made more compact. This makes it easier to position the connector 31 at a desired location on the backplane 3, which has the advantage of improving the design flexibility of the communication device 1.

[0069] For example, by making the connector 31 for the CT more compact, the size of the ventilation opening 32 of the backplane 3 can be increased or its shape changed, thereby improving the airflow of cooling air inside the communication device 1. Furthermore, when considering new communication equipment, there is a high possibility that only the PW (Power Wave) will need to be newly designed, while the CT (Critical Turn Signal) and FN (Functional Network) units will be reused from those of communication equipment 1.

[0070] To address the redundancy of PW and FN, a backplane 3 should be adopted with wiring that allows PW1 and PW2 to connect to CT1, FN1, FN2, and FN3 respectively, and also allows PW1 and PW2 to connect to each other. In this case, the number of signal lines required for the PW connector 31 is 5 lines × 5 units = 25 lines. However, this number is still less than the number of signal lines required for the CT1 connector 31 in connection configuration 1 of Figure 3 (= 35 lines).

[0071] [Communication control in connection type 2] As described above, adopting connection configuration 2, which uses the PW as a relay unit, has the structural advantage of allowing the connector 31 for the CT to be made more compact. However, in connection configuration 2, where a relay unit is provided, it is necessary to employ the following multiple communication controls in order to ensure proper communication between units.

[0072] (Communication control 1) Communication control 1 is a control that transmits the first control signal and the second control signal to the first signal line 35A without collision. Communication control 1 includes downlink time division multiplexing (Figure 5) and uplink time division multiplexing (Figure 6). (Communication control 2) Communication control 2 is a control method in which the relay unit PW adds the EXT (insertion complete) status of its subordinate FN to the RDY (startup status) that the CT periodically notifies it of.

[0073] (Communication control 3) Communication control 3 is a control in which the monitoring CT adds FN identification information (for example, the FN connector number) to the RST (restart request) sent to the PW. (Communication control 4) Communication control 4 is a control that autonomously switches the operating state (= relay function) of the redundant PW1 and PW2 when the PW is configured redundantly.

[0074] The following describes the embodiments of each communication control described above with reference to Figures 5 to 9. In Figures 5 to 9, "HDLC_TX" represents the transmission function of a communication frame compliant with HDLC containing a predetermined control signal (hereinafter abbreviated as "communication frame"). "HDLC_RX" represents the reception function of a communication frame.

[0075] In Figures 5 through 9, "QiRj_HDLC" written below the arrows refers to the name of the physical wiring between the units, where the unit connected to the transmitter is Qi and the unit connected to the receiver is Rj. Furthermore, the rectangle above the arrow and the "SiTj" inside it represent a communication frame where the source is Si and the destination is Tj.

[0076] "XXk_EXT" represents a communication frame that notifies the insertion of unit XXk (connection to connector 31). "YYl_RDY" represents a communication frame that notifies the startup status of unit YYl. "ZZm_RST" represents a communication frame that notifies a restart request for unit ZZm.

[0077] However, Q to T are variables representing the first letter of one of the units CT, PW, and FN, and XX, YY, and ZZ are variables representing one of the units CT, PW, and FN. Also, i to m are variables representing the identification number of the same type of unit.

[0078] [Example of communication control 1] Figures 5 and 6 are explanatory diagrams showing an embodiment of communication control 1. Specifically, Figure 5 is an explanatory diagram showing an example of time-division multiplexing in the downlink direction. Figure 6 is an explanatory diagram showing an example of time-division multiplexing in the uplink direction.

[0079] As shown in Figure 5, when CT1 transmits a communication frame to four units, for example PW1, FN1, FN2, and FN3, it sends C1P1, C1F1, C1F2, and C1F3, which it has generated, one by one to C1P1_HDLC (first signal line 35A) in time division multiplexing. In this case, C1P1 is the first downlink control signal, and C1F1, C1F2, and C1F3 are the second downlink control signals.

[0080] Next, PW1 performs the following processing on the received downlink communication frame. Process 1: Receive a communication frame (first control signal) addressed to itself. Process 2: Provided that the unit is in an operational state (Act), it forwards a communication frame (second control signal) for monitoring non-relay units in the downstream direction.

[0081] Therefore, in the example in Figure 5, PW1 receives C1P1 and performs the processing requested by this communication frame. Furthermore, if PW1 is in an operational state (Act), it sends C1F1, C1F2, and C1F3 to the second signal line 35B, which is P1F1_HDLC, P1F2_HDLC, and P1F3_HDLC respectively, and broadcasts them to FN1, FN2, and FN3.

[0082] In this case, FN1, FN2, and FN3 should accept the communication frame received from PW1 if it is addressed to them, and discard it if it is not. In this way, by performing downlink transmission to the PW in a time-division manner, the CT can transmit the first and second control signals in the downlink direction to the first signal line 35A without collision.

[0083] As shown in Figure 6, PW1 has multiple (four in the example) input-1-output switching circuits SW. The input side of the switching circuits SW is connected to multiple uplink transmit buffers BF1 to BF4.

[0084] The transmit buffer BF1 stores the communication frames received from FN1. These communication frames are the uplink second control signals generated by FN1. The transmit buffer BF2 stores the communication frames received from FN2. These communication frames are the uplink second control signals generated by FN2.

[0085] The transmit buffer BF3 stores the communication frames received from FN3. These communication frames are the uplink second control signals generated by FN3. The transmit buffer BF4 stores the communication frames generated by the frame processing unit of the device (PW1). The frame processing unit generates P1C1 addressed to CT1 in response to C1P1 addressed to itself and places them in the transmit buffer BF4. This communication frame is the first uplink control signal.

[0086] PW1 has an output control unit that inputs switching information to the switching circuit SW. Based on the communication frame accumulation status of the transmit buffers BF1, BF2, BF3, and BF4, the output control unit determines which communication frames from transmit buffers BF1, BF2, BF3, and BF4 to transmit in the uplink direction.

[0087] For example, if P1C1_HDLC is not currently sending a communication frame, and a communication frame is stored in the transmit buffer BF4, the switching information of the transmit buffer BF4 is input to the gate of the switching circuit SW, and it is selected as an uplink communication frame to be sent by P1C1 to P1C1_HDLC.

[0088] Similarly, if no communication frames are currently being sent to P1C1_HDLC and communication frames are stored in the transmit buffer BF1, the switching information of the transmit buffer BF1 is input to the gate of the switching circuit SW, and F1C1 is selected as the uplink communication frame to be sent to P1C1_HDLC. The same selection process as described above also applies when communication frames are stored in transmit buffers BF2 and BF3.

[0089] Since CT1 transmits downlink communication frames one by one using time-division multiplexing, the gate input to the switching circuit SW due to the accumulation of communication frames in the transmit buffers BF1, BF2, BF3, and BF4 occurs at approximately the same frequency as the downlink frame transmission interval. In this way, by performing the uplink transmission to the CT in a time-division manner, the first and second uplink control signals can be transmitted to the first signal line 35A without collision.

[0090] [Example of communication control 2] Figure 7 is an explanatory diagram showing an embodiment of communication control 2. As shown in Figure 7, assume that only FN1 is inserted under PW1, and that the insertion information (for example, the connector number corresponding to FN1) is recorded in the memory of PW1 via inter-unit communication between PW1 and FN1. In this case, PW1 adds FN1_EXT to the data area of ​​PW1_RDY, which is used to notify its own startup status, and sends the modified PW1_RDY to P1C1_HDLC, which then sends it to CT1.

[0091] Upon receiving the above PW1_RDY, CT1 decodes the communication frame, extracts FN1_EXT, and records the extracted information in memory. This allows CT1 to check the insertion information of FN1, which is not directly connected to itself, and to store the insertion information of FN1.

[0092] [Example of communication control 3] Figure 8 is an explanatory diagram showing an embodiment of communication control 3. As shown in Figure 8, CT1 sends FN1_RST to C1P1_HDLC to notify FN1 of a restart request. As mentioned above, FN1_RST contains identification information (e.g., slot number) of the FN1 to be restarted.

[0093] Upon receiving the above FN1_RST, PW1 decodes the communication frame and, if it determines that it is not a communication frame addressed to itself, it broadcasts FN1_RST to P1F1_HDLC, P1F2_HDLC, and P1F3_HDLC.

[0094] In this case, as a result of decoding the communication frame, only FN1 will perform a reboot in response to an RST addressed to itself, while FN2 and FN3 will discard RSTs that are not addressed to themselves. In this way, PW1 broadcasts an RST (which includes the identification information of FN1) downstream to its subordinate FN1, allowing CT1 to have PW1 act on its behalf to send restart requests (RSTs) to FN1 that are not directly connected to it.

[0095] [Example of communication control 4] Figure 9 is an explanatory diagram showing an embodiment of communication control 4. In Figure 9, "unit insertion position information" represents the insertion position of the unit relative to the backplane 3, and PW1 and PW2 hold position information values ​​according to, for example, the connector number of the backplane 3 into which the unit is inserted. Here, we assume that when the position information of PW1 is [1] and the position information of PW2 is [0], the unit with the larger number becomes operational and the unit with the smaller number remains inactive.

[0096] As shown in Figure 9, PW2 sends P2P1 containing location information = 0 to PW1. Upon receiving P2P1, PW1 compares its own location information = 1 with PW2's location information = 0 to determine its own operating state. In this case, since the position information of PW1 is greater than that of PW2, PW1 sets its own operating state to the operating state (Act).

[0097] Conversely, PW1 sends P1P2, which includes location information=1, to PW2. Upon receiving P1P2, PW2 compares its own location information=0 with PW1's location information=1 to determine its own operating state. In this case, since the position information of PW2 is smaller than that of PW1, PW2 sets its operating state to the idle state (Stby).

[0098] When PW1 is operational, it broadcasts downlink communication frames (second control signals) to its subordinate FNs, but when PW2 is inactive, it does not transmit downlink or uplink communication frames. This prevents downlink and uplink communication frames from being delivered to the FN or CT twice.

[0099] Even if the dormant PW2 is removed, the active PW1 continues to relay communication frames, thus maintaining communication between the CT and FN. When the active PW1 is removed, the dormant PW2 becomes active due to the loss of communication with PW1 and begins relaying downstream communication frames. Therefore, even if PW1 is removed, communication between the CT and FN is maintained.

[0100] Figure 9 illustrates the case with two PWs, but the PWs may be redundant with N (N≧3) units. In this case, among the N PWs, the unit that determines through the inter-unit communication described above to have the maximum unit insertion position information enters an operational state (Act) and functions as a relay unit.

[0101] [Regular status monitoring] Figure 10 is a sequence diagram showing an example of periodic status monitoring performed by inter-unit communication within the communication device 1. Here, CT1 is the primary monitoring unit for status monitoring, and the seven units being monitored while inserted into backplane 3 are LN1, LN2, PW1, PW2, FN1, FN2, and FN3.

[0102] In Figure 10, "CHE" is a communication frame requesting a status check. "ACK" is a response frame. Possible check targets include the unit insertion status, the optical transceiver insertion status, the board temperature, and the fan speed. CT1 periodically performs a status check of all units by sending a CHE to each unit inserted into the backplane 3 and receiving an ACK from each unit. In other words, the sequence in Figure 10 is executed periodically at predetermined intervals.

[0103] As shown in Figure 10, CT1 sends C1P1_CHE to PW1. In this case, PW1 performs the specified status check and sends P1C1_ACK containing the check result to CT1 (step S11). Next, CT1 sends C1P2_CHE to PW2. In this case, PW2 performs the specified status check and sends P2C1_ACK containing the check result to CT1 (step S12).

[0104] Next, CT1 sends C1F1_CHE to PW1 and PW2 (step S13). If PW1 is in Act mode and PW2 is in Stby mode, then only PW1 sends C1F1_CHE to FN1, FN2, and FN3 (step S14). In this case, only FN1 receives C1F1_CHE, performs the specified status check, and sends F1C1_ACK containing the check result to PW1 and PW2 (step S15). PW1 forwards the received F1C1_ACK to CT1 (step S16).

[0105] Next, CT1 performs the same process for FN2 and FN3 as in step S13 (sending a CHE to FN2 or FN3). As a result, CT1 obtains the check results of the status check performed by FN2 and FN3.

[0106] Next, CT1 sends C1L1_CHE to LN1. In this case, LN1 performs the specified status check and sends L1C1_ACK containing the check result to CT1 (step S17). Finally, CT1 sends C1L2_CHE to LN2. In this case, LN2 performs the specified status check and sends L2C1_ACK containing the check result to CT1 (step S18).

[0107] In the example shown in Figure 10, CT1 sends communication frames requesting a status check (CHE) in the order of PW → FN → LN, but the transmission order is not limited to this, and other orders such as LN → PW → FN may also be used.

[0108] As shown in Figure 10, the first control signal transmitted and received between CT1 and PW1 includes a check request (C1P1_CHE) in which CT1 requests PW1 to perform a status check, and a check response (P1C1_ACK) in which PW1 responds to CT1 with the check result. Similarly, C1P2_CHE and P2C1_ACK also correspond to the first control signal. Therefore, CT1 can also instruct the relay units PW1,PW1 to perform status checks.

[0109] As shown in Figure 10, the second control signal relayed by PW1 includes a check request (C1F1_CHE) in which CT1 requests FN1 to perform a status check, and a check response (F1C1_ACK) in which FN1 responds to CT1 with the check result. Therefore, CT1 can instruct status checks not only for units directly connected to it (LN and PW), but also for FN units that are not directly connected to it.

[0110] [Monitoring the state when an event occurs] Figure 11 is a sequence diagram showing an example of status monitoring when an event occurs, which is performed by inter-unit communication within the communication device 1. In Figure 11, "ALM" is a communication frame that warns of an anomaly. Anomalies include, for example, excessive temperature rise or excessive time error. Here, we assume that LN1 detects an excessive temperature rise and sends an ALM.

[0111] "INC" is a communication frame that requests FN to increase the fan speed, and "RTN" is a communication frame that requests FN to return the fan speed to normal. As shown in Figure 11, LN1, having detected an excessive temperature rise, sends L1C1_ALM to CT1 (step S21).

[0112] Next, CT1 sends C1L1_CHE to LN1, prompting LN1 to check the board temperature status. LN1 then sends L1C1_ACK, which includes the check result, to CT1 (step S22). Here, we assume that CT1 judges the reported substrate temperature to be excessive and selects FN1 as an FN located in a suitable position to lower the substrate temperature of LN1.

[0113] In this case, CT1 sends C1F1_INC to PW1 and PW2 (step S23). If PW1 is in Act mode and PW2 is in Stby mode, then only PW1 sends C1F1_INC to FN1, FN2, and FN3 (step S24). In this case, only FN1 receives C1F1_INC and increases the fan speed, and sends F1C1_ACK to PW1 and PW2 to indicate that it has responded to the increase (step S25). PW1 forwards the received F1C1_ACK to CT1 (step S26).

[0114] After a predetermined time (e.g., 10 minutes) has elapsed during which a temperature decrease due to increased airflow can be expected, CT1 sends C1L1_CHE to LN1, prompting LN1 to recheck the substrate temperature. LN1 then sends L1C1_ACK, which includes the check result, to CT1 (step S27). Here, we assume that CT1 has determined the notified substrate temperature to be normal.

[0115] In this case, CT1 sends C1F1_RTN to PW1 and PW2 (step S28). If PW1 is in Act mode and PW2 is in Stby mode, then only PW1 sends C1F1_RTN to FN1, FN2, and FN3 (step S29). In this case, only FN1 receives C1F1_RTN and returns the fan speed to normal, and sends F1C1_ACK to PW1 and PW2 indicating that the speed has been returned to normal (step S30). PW1 forwards the received F1C1_ACK to CT1 (step S31).

[0116] As shown in Figure 11, the second control signal relayed by PW1 includes an operation request (C1F1_INC) that requests FN1 to perform a predetermined action (in this case, an increase in fan speed) and an operation response (F1C1_ACK) in which FN1 responds to CT1 that the action has been completed. Therefore, CT1 can instruct not only the units directly connected to it (LN and PW) but also the FN units that are not directly connected to it to perform predetermined operations.

[0117] As shown in Figure 11, the second control signal relayed by PW1 includes a release request (C1F1_RTN) that requests FN1 to cancel a predetermined operation (in this case, cancel the increase in fan speed), and a release response (F1C1_RTN) in which FN1 responds to CT1 that the release is complete. Therefore, CT1 can instruct not only the units directly connected to it (LN and PW) to cancel a predetermined operation, but also the FN which is not directly connected to it.

[0118] [Status monitoring and control by the control unit] Figure 12 is a flowchart showing an example of status monitoring control performed by CT1 during operation. In Figure 12, "n" is a variable representing the connector number of backplane 3 (n=1, 2, ...), and "N" is the number of connectors 31 installed on backplane 3.

[0119] As shown in Figure 12, CT1 sets the variable n to its initial value (=1) (step ST11), and then determines whether a unit is inserted into the connector 31 of variable n (step ST12).

[0120] If the result of step ST12 is negative, CT1 skips steps ST13 to ST17 and proceeds to step ST18. If the result of step ST12 is positive, CT1 determines whether or not communication with the unit of variable n is possible (step ST13). This determination is performed, for example, by determining whether or not the number of FCS anomalies exceeds a threshold.

[0121] If the result of step ST13 is negative, CT1 issues a reset notification (step ST20). The reset notification is a process that sends instructions to the management computer, such as to reconnect or replace the unit. If the result of step ST13 is positive, CT1 determines whether or not an alarm has occurred in the unit of variable n (step ST14).

[0122] If the result of step ST14 is negative, CT1 performs additional processing to identify the cause of the alarm (step ST21). If the result of step ST14 is positive, CT1 determines whether inter-unit communication is normal or not (step ST15). This determination is performed, for example, by determining whether the number of data communication abnormalities within a predetermined time exceeds a threshold.

[0123] If the result of step ST15 is negative, CT1 issues a fault notification (step ST22). A fault notification is, for example, the process of sending information about a unit failure to the management computer. If the result of step ST15 is positive, CT1 determines whether the substrate temperature of the unit of variable n is normal or not (step ST16). This determination is performed based on whether the substrate temperature reported by the unit exceeds a threshold.

[0124] If the result of step ST16 is negative, CT1 performs a fan speed change process (step ST23). The change process is, for example, a process of commanding a predetermined FN to increase the fan speed. If the result of step ST16 is positive, CT1 determines whether the RTC (Real-Time Clock) of the unit of variable n is functioning correctly (step ST17).

[0125] If the result of step ST17 is negative, CT1 performs time correction with the unit of variable n (step ST24). Time correction is performed, for example, by notifying the unit of the time difference between CT1 and the unit. If the result of step ST17 is positive, CT1 increments the variable n (step ST18) and then determines whether the variable n = N or not (step ST19).

[0126] If the result of step ST19 is negative, CT1 returns to the state before step ST12. If the result of step ST19 is positive, CT1 terminates the process. This ends the status monitoring for all units mounted on backplane 3.

[0127] [Problems and solutions when the control unit's communication is interrupted] As described in connection configurations 1 and 2 above, if there is only one control unit 4 which is the monitoring entity, then during periods when communication with control unit 4 is impossible due to reasons such as the removal or malfunction of control unit 4, the other units 5, 6, and 7 that are being monitored will no longer be monitored. In this case, even if the line unit 5, which is the target of high-temperature protection, becomes hot, the fan unit 7 cannot be controlled, and there is a problem that the line unit 5, which performs the function of high-speed Ethernet communication such as 10 Gigabit, cannot be properly protected.

[0128] One possible solution to the above problems is to make the control unit 4 redundant. However, in this case, the number of monitoring signal lines 35 for inter-unit communication will increase by the amount of the additional control unit 4, which will contribute to the enlargement of the connector 31 on the backplane 3. In addition, adding a second control unit 4 would require extra physical space within the chassis 2. Therefore, it may become necessary to increase the size of the chassis 2 from 1U to 2U. Therefore, in this embodiment, when the line unit 5 detects a communication interruption in the control unit 4, the line unit 5 takes over the control of the fan unit 7 using the alternative control lines 36 originally provided by the backplane 3 and connector 31, thereby preventing the line unit 5 from overheating while suppressing the number of wires in the connector 31.

[0129] Hereinafter, the control in which the line unit 5 operates the fan unit 7 in place of the control unit 4 will be referred to as "substitute control." In this embodiment, the following two types of control are presented as substitute control using the substitute control line 36 by the line unit 5. The execution entity for the following two types of control is one of the signal processing units 42, 52, 62, or 72 in each of the units 4, 5, 6, and 7.

[0130] (Substitute control 1) Substitute control 1 is a control that includes the following processes P11, P12, and P13. Process P11: While communication is being established with control unit 4, the signal on alternative control line 36 is turned OFF. Process P12: While communication with control unit 4 is interrupted, the signal on alternative control line 36 is turned ON. Process P13: If the signal of the alternative control line 36 is OFF, the control unit 4 maintains control at the last specified fan speed. If the signal of the alternative control line 36 is ON, the fan speed is set to a predetermined value (e.g., 100%).

[0131] (Substitute control 2) Substitute control 2 is a control that includes the following processes P21 and P22. Process P21: While the control unit 4 is establishing communication, the line unit 5 and one or more fan units 7 synchronize their clocks with each other. Process P22: When communication with control unit 4 is interrupted, line unit 5 sends a PWM signal to alternative control line 36 to control the fan speed.

[0132] [Example 1 of Proxy Control 1] Figure 13 is an explanatory diagram showing Embodiment 1 of the proxy control 1. Embodiment 1 in Figure 13 is applicable to both connection configuration 1 (Figure 3) and connection configuration 2 (Figure 4). In Figure 13, "CT" represents control unit 4, "LN" represents line unit 5, and "FN" represents fan unit 7. The numbers following CT, LN, and FN are the identification numbers of each unit.

[0133] "FFC" (Fan Force Control) is an alternative control signal for the alternative control line 36, and is normally set to OFF (negated). Here, we will explain the operation of the signal processing unit 72 of FN3, one of the redundant FNs FN1, FN2, and FN3, but FN1 and FN2 operate similarly. Flowchart F1 in Figure 13 shows the procedure performed by the signal processing unit 52 of LN1, and flowchart F2 shows the procedure performed by the signal processing unit 72 of FN3. The processes in flowcharts F1 and F2 are executed at predetermined control cycles (e.g., 1 second).

[0134] As shown in Figure 13, the signal processing unit 52 of LN1 determines whether CT1 is functioning or not by monitoring the status of inter-unit communication (step ST31) (step ST32). If the result of step ST32 is positive, the signal processing unit 52 repeats the liveness check in step ST31. If the result of step ST32 is negative, it is determined whether the temperature of the unit is high or not (step ST33).

[0135] This determination is made based on whether the temperature sensor installed in LN1 measures a predetermined value (for example, 60 degrees Celsius) or higher. If the result of step ST33 is negative, the signal processing unit 52 repeats the liveness check in step ST31. If the result of step ST33 is positive, the signal processing unit 52 switches FFC ON (assert) (step ST34).

[0136] As shown in Figure 13, the signal processing unit 72 of FN3 monitors the state of FFC (step ST41) and determines whether FFC is ON (asserted) or not (step ST42). If the result of step ST42 is negative (FFC=OFF), the signal processing unit 72 performs normal mode fan control (step ST43). The normal mode is a control system that determines its own fan speed according to the fan speed control information received from CT1 (for example, INC and RTN in Figure 11).

[0137] If the result of step ST42 is positive (FFC = ON), the signal processing unit 72 performs forced mode fan control (step ST44). The forced mode is a control that changes the fan speed to a predetermined value (e.g., 100%) in response to the detection of FFC being ON.

[0138] [Example 2 of Proxy Control 1] Figure 14 is an explanatory diagram showing Example 2 of the proxy control 1. Example 2 in Figure 14 is applicable only to connection configuration 2 (Figure 4). In Figure 14, "CT" represents control unit 4, "LN" represents line unit 5, "PW" represents power supply unit 6, and "FN" represents fan unit 7. The numbers following CT, LN, PW, and FN are the identification numbers of each unit.

[0139] "FFC" (Fan Force Control) is an alternative control signal for alternative control line 36, and is normally set to OFF (negated). Here, we assume that of the redundant PWs PW1 and PW2, PW2 is in the operational state (Act). Flowchart F1 in Figure 14 shows the procedure performed by the signal processing unit 52 of LN1, and flowchart F3 shows the procedure performed by the signal processing unit 62 of PW2. The processes in flowcharts F1 and F3 are executed at predetermined control cycles (e.g., 1 second).

[0140] Flowchart F1 in Figure 14 is the same as flowchart F1 in Figure 13. Therefore, the signal processing unit 52 of LN1 performs the same processing as in the case of Embodiment 1 in Figure 13.

[0141] As shown in Figure 14, the signal processing unit 62 of PW2 monitors the state of FFC (step ST51) and determines whether FFC is ON (asserted) or not (step ST52). If the result of step ST52 is negative (FFC=OFF), the signal processing unit 62 performs normal mode fan control (step ST53). The normal mode is a control method that transmits a communication frame containing fan speed control information received from CT1 (for example, INC and RTN in Figure 11) to FN1, FN2, and FN3.

[0142] If the result of step ST52 is positive (FFC = ON), the signal processing unit 62 performs forced mode fan control (step ST54). The forced mode is a control method in which, upon detection of FFC ON, the signal processing unit 62 generates a communication frame containing control information indicating that the fan speed is at a predetermined value (e.g., 100%), and transmits the generated communication frame to FN1, FN2, and FN3. If there is an alternative control line between PW2 and each FN, that control line may be driven in addition to transmitting the communication frame.

[0143] [Example of Proxy Control 2] Figure 15 is a block diagram showing an embodiment of the proxy control 2. The embodiment in Figure 15 is applicable to both connection configuration 1 (Figure 3) and connection configuration 2 (Figure 4). As shown in Figure 15, the signal processing unit 42 of the control unit 4 includes a communication unit 401 and a fan control unit 402. The communication unit 401 is a functional unit that performs inter-unit communication with other units 5, 6, and 7 using a monitoring communication frame transmitted on the monitoring signal line 35.

[0144] The fan control unit 402 is a functional unit that performs "fan speed control" using the alternative control line 36. The fan speed calculation is performed in response to the input of the control signal S1 from the communication unit 401. The fan control unit 402 includes an oscillator 411, a clock generation unit 412, a counting unit 413, a carrier wave generation unit 414, a calculation unit 415, and a PWM signal generation unit 416.

[0145] The oscillator 411 is, for example, a crystal oscillator. The clock generation unit 412 is, for example, a frequency multiplier. The clock generation unit 412 generates a clock CLK1 by multiplying the frequency of the output clock of the oscillator 411, and outputs the generated clock CLK1 to the counting unit 413 and the calculation unit 415.

[0146] The counting unit 413 is a circuit that includes, for example, a frequency divider and an up / down counter. The counting unit 413 outputs a count value C1 to the carrier wave generation unit 414, which is obtained by up-counting and down-counting the number of clocks after frequency division of the clock CLK1. The carrier wave generation unit 414 generates a carrier wave W1, such as a triangular wave, based on the input count value C1. The triangular wave W1 is generated, for example, by accumulating and adding voltage values ​​during up-counting and accumulating and subtracting voltage values ​​during down-counting.

[0147] The communication unit 401 outputs a control signal S1 to the calculation unit 415. The control signal S1 is a command that instructs the fan speed to increase or decrease in response to, for example, the substrate temperature notified by the line unit 5. The calculation unit 415 determines the duty cycle D1 based on the control signal S1 and outputs the determined duty cycle D1 to the PWM signal generation unit 416. The PWM signal generation unit 416 generates a PWM signal based on the input carrier wave W1 and duty cycle D1 and outputs the generated PWM signal to the alternative control line 36.

[0148] As shown in Figure 15, the signal processing unit 52 of the line unit 5 includes a communication unit 501 and a fan control unit 502. The communication unit 501 is a functional unit that performs inter-unit communication with the control unit 4 using a monitoring communication frame transmitted on the monitoring signal line 35.

[0149] The fan control unit 502 is a functional unit that includes "clock synchronization" using the alternative control line 36 and "fan speed control" using the alternative control line 36 as switchable control types. Switching between control types is performed by a control signal S2 output by the communication unit 501. The fan control unit 502 includes an oscillator 511, a clock generation unit 512, a counting unit 513, a carrier wave generation unit 514, a calculation unit 515, a PWM signal generation unit 516, and a synchronization processing unit 517.

[0150] The oscillator 511 is, for example, a crystal oscillator. The clock generation unit 512 is, for example, a frequency multiplier. The clock generation unit 512 generates a clock CLK2 by multiplying the frequency of the output clock of the oscillator 511, and outputs the generated clock CLK2 to the counting unit 513, the calculation unit 515, and the synchronization processing unit 517.

[0151] The counting unit 513 is a circuit that includes, for example, a frequency divider and an up / down counter. The counting unit 513 outputs a count value C2 to the carrier wave generation unit 514, which is obtained by up-counting and down-counting the number of clocks after frequency division of the clock CLK2. The carrier wave generation unit 514 generates a carrier wave W2, such as a triangular wave, based on the input count value C2. The triangular wave W2 is generated, for example, by accumulating and adding voltage values ​​during up-counting and accumulating and subtracting voltage values ​​during down-counting.

[0152] The synchronization processing unit 517 receives the PWM signal from the alternative control line 36 (the PWM signal generated by the signal processing unit 402) and the clock CLK2 as input. The synchronization processing unit 517 detects the phase difference between the rising edge of the input PWM signal and the clock CLK2, and outputs the detected phase difference to the clock generation unit 512. The clock generation unit 512 adjusts the phase of the clock CLK2 in a direction that eliminates the input phase difference.

[0153] The communication unit 501 outputs a control signal S2 to the calculation unit 515. The control signal S2 is a signal that commands the fan control unit 502 to execute an operating mode (mode 1 or mode 2). The communication unit 501, based on the results of the status check via inter-unit communication, sets the control signal S2 to a mode 1 (clock synchronization) command if the control unit 5 is functioning correctly, and sets the control signal S2 to a mode 2 (fan control) command if the control unit 5 is not functioning correctly.

[0154] Mode 1: Clock synchronization command PWM signal generation unit 516 = Disable (Inactive) Synchronization processing unit 517 = Enable (enabled) Mode 2: Fan control commands PWM signal generation unit 516 = Enable (enabled) Synchronization processing unit 517 = Disabled

[0155] When the calculation unit 415 receives a command for mode 2 (fan control) via the control signal S2, it determines the duty cycle D2 based on the board temperature of its own unit 5 and outputs the determined duty cycle D2 to the PWM signal generation unit 516. The PWM signal generation unit 516 generates a PWM signal based on the input carrier wave W2 and duty cycle D2, and outputs the generated PWM signal to the alternative control line 36.

[0156] As shown in Figure 15, the signal processing unit 72 of the fan unit 7 includes a communication unit 701 and a fan drive unit 702. The communication unit 701 is a functional unit that performs inter-unit communication with other units 4, 5, and 6 using a monitoring communication frame transmitted on the monitoring signal line 35.

[0157] The fan drive unit 702 is a functional unit that performs "clock synchronization" using the alternative control line 36 and "fan drive" using the alternative control line 36. The fan drive unit 702 includes an oscillator 711, a clock generation unit 712, a motor drive unit 713, and a synchronization processing unit 714.

[0158] The oscillator 711 is, for example, a crystal oscillator. The clock generation unit 712 is, for example, a frequency multiplier. The clock generation unit 712 generates a clock CLK3 by multiplying the frequency of the output clock of the oscillator 511 and outputs it to the motor drive unit 713 and the synchronization processing unit 714.

[0159] The synchronization processing unit 714 receives the PWM signal from the alternative control line 402 (the PWM signal generated by the signal processing unit 42 or the signal processing unit 52) ​​and the clock CLK3 as input. The synchronization processing unit 714 detects the phase difference between the rising edge of the input PWM signal and the clock CLK3, and outputs the detected phase difference to the clock generation unit 712. The clock generation unit 712 adjusts the phase of the clock CLK3 in a direction that eliminates the input phase difference.

[0160] The motor drive unit 713 is a circuit that includes multiple switching elements that convert DC power to three-phase AC power. The motor drive unit 713 detects the rising edge of the PWM signal according to the synchronized clock CLK3. The motor drive unit 713 also converts the DC power from the DC distribution line 34 into three-phase AC power by switching multiple switching elements on and off in response to the PWM signal, and supplies the converted power to the electric motor M of the cooling fan 73.

[0161] The motor drive unit 713 can output the current fan speed to the communication unit 701. The fan speed is calculated, for example, from an equation or table that shows the correspondence between the PWM signal and the fan speed. When the communication unit 701 receives a fan speed request frame (CHE in Figure 10), it generates a response frame (ACK in Figure 10) containing the fan speed notified by the motor drive unit 713, and transmits the generated response frame.

[0162] In the embodiment shown in Figure 15, there is only one signal processing unit 52 in the line unit 5, but two or more signal processing units 52 of line units 5 may share the alternative control line 36. In this case, multiple fan control units 502 can each output PWM signals with different duty cycles D2 to the alternative control lines 36. In this case, since the fan control units 502 are clock-synchronized with the fan control units 502 of other line units 5, the fan drive unit 702 (motor drive unit 713) drives the electric motor M of the cooling fan 73 in accordance with the PWM signal with the largest duty cycle D2.

[0163] In the embodiment shown in Figure 15, there is only one signal processing unit 72 in the fan unit 7, but two or more fan unit 7s may share the alternative control line 36. In this case, since the same PWM signals with duty cycles D1 and D2 are input to multiple fan drive units 702, the fan speeds in each fan unit 7 will be the same.

[0164] [First variation] As shown in the flowchart in Figure 12, the control unit 4 performs time correction as part of the state monitoring control using inter-unit communication (step ST24 in Figure 12). Therefore, in the embodiment shown in Figure 15, the signal processing unit 42 of the control unit 4 may choose not to perform clock synchronization using a PWM signal.

[0165] However, in connection configuration 2 (Figure 4), a communication delay occurs due to the relay of the power supply unit 6. Therefore, when performing clock synchronization based on inter-unit communication, it is preferable to perform clock synchronization of the line unit 5 and the fan unit 7 while taking the above-mentioned communication delay into consideration.

[0166] [Second variation] In the above embodiment, a communication device 1 with only one alternative control line 36 was illustrated. However, if there is only one bus-connected alternative control line 36, the alternative control line 36 may become unusable if any one of the units 4, 5, 6, or 7 fails. Therefore, if there is sufficient capacity in the connector 31, multiple alternative control lines 36 may be provided for purposes such as backup in case of failure. Even in this case, the number of wires in the connector 31 can be reduced compared to adding a star-connected control unit 4.

[0167] [Third variation] In the above embodiment, the non-relay unit connected to the relay unit (power supply unit 6) may be the line unit 5, not just the fan unit 7. In this case, the power supply unit 6 may be equipped with a communication processing unit (management communication LSI) 45, the communication processing unit 45 of the control unit 4 may be connected to the communication processing unit 45 of the power supply unit 6 via a management signal line 33, and the communication processing unit 45 of the power supply unit 6 may be connected to the CPU 53 of the line unit 5 via the management signal line 33.

[0168] In this way, not only the monitoring signal line 35 but also the management signal line 33 can be avoided from being concentrated on the control unit 4 due to the increase in the number of line units 5, and the connector 31 for the control unit 4 can be made more compact. Therefore, the communication medium for inter-unit communication in this embodiment is not limited to the monitoring signal line 35, but can be any signal line that can be implemented on the backplane 3, such as the management signal line 33 mentioned above. In addition, the monitoring control signal also includes management information for setting the communication function.

[0169] [Other variations] The embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments described above, and includes all modifications within the scope equivalent to the configurations described in the claims. For example, in the above embodiment, the unit to be protected from high temperatures may be not only the line unit 5, but also other units included in the communication device 1, such as the power supply unit 6.

[0170] In the above-described embodiment, a unit other than the power supply unit 6 may be used as the relay unit. However, even in the case of an electronic device with a plug-and-play live-wire system, the installation of the power supply unit 6 is essential, so it is preferable that the relay unit be the power supply unit 6. Furthermore, the electronic device in this disclosure may be not only the communication device 1, but also a computer device such as a server. [Explanation of Symbols]

[0171] 1 Communication equipment (electronic equipment) 2 cabinets 3 Backplane 4. Control Unit 5 Line Unit (Controlled Unit, 1st Unit) 6. Power supply unit (controlled unit, third unit) 7. Fan unit (controlled unit, second unit) 21 Front opening 22 Rear opening 30 Backplane 31 Connectors 32 Ventilation hole 33 Management signal line 34 DC distribution line 35 Monitoring signal line 35A 1st signal line 35B 2nd signal line 35C 3rd signal line 36 Alternative control lines 40 Circuit boards 41 Connectors 42 Signal Processing Unit 43 CPU 44 memory 45 Communication Processing Unit 46 Management Ports 47 Power supply section 50 Circuit boards 51 Connectors 52 Signal Processing Unit 53 CPU 54 memory 55 Switch section 56 External Ports 57 Power supply section 60 Circuit boards 61 Connectors 62 Signal Processing Unit 63 First Voltage Conversion Unit 64 Second Voltage Conversion Section 70 Circuit boards 71 Connectors 72 Signal Processing Unit 73 Cooling fan 74 Power supply section 401 Communications Department 402 Fan Control Unit 411 Oscillator 412 Clock generation unit 413 Counting section 414 Carrier wave generation unit 415 Arithmetic section 416 PWM signal generation section 501 Communications Department 502 Fan Control Unit 511 Oscillator 512 Clock generation unit 513 Counting section 514 Carrier wave generation unit 515 Arithmetic section 516 PWM signal generation section 517 Synchronization Processing Unit 701 Communications Department 702 Fan drive unit 711 Oscillator 712 Clock generation unit 713 Motor drive unit 714 Synchronization Processing Unit

Claims

1. Backplane and A control unit which is a monitoring unit that can be mounted on the backplane, An electronic device comprising a plurality of controlled units that are objects to be monitored and can be mounted on the backplane, The aforementioned backplane is The control unit includes a monitoring communication line for inter-unit communication between the control unit and the plurality of controlled units, and a bus-connected alternative control line. The plurality of controlled units are, It includes a first unit that is subject to high temperature protection and a second unit that drives a cooling fan, The first unit is, An electronic device that, upon a communication failure of the control unit, performs substitute control to operate the second unit using the alternative control line instead of the control unit.

2. The aforementioned alternative control line is, The outputs of one or more of the first units are connected via wired logic, If at least one output of the first unit is ON, the value of the alternative control line becomes asserted. The aforementioned substitute control is, The electronic device according to claim 1, wherein the first unit includes a process of keeping the output to the alternative control line OFF while communication with the control unit is established, and turning on the output to the alternative control line when communication with the control unit is interrupted.

3. The first unit and the second unit are, The bus is connected via the aforementioned alternative control line. The aforementioned substitute control is, The electronic device according to claim 2, wherein the second unit controls the fan speed based on control information received from the control unit when the value of the alternative control line is negated, and sets the fan speed to a predetermined value when the value of the alternative control line is asserted.

4. The plurality of controlled units are, It includes a third unit which is a relay node between the control unit and the second unit, The first unit and the third unit are, The bus is connected via the aforementioned alternative control line. The aforementioned substitute control is, The electronic device according to claim 2, further comprising the process by which the third unit transmits control information received from the control unit to the second unit if the value of the alternative control line is negated, and transmits control information to the second unit to set the fan speed to a predetermined value if the value of the alternative control line is asserted.

5. The first unit and the second unit are The bus is connected via the aforementioned alternative control line. The aforementioned substitute control is, The electronic device according to any one of claims 1 to 4, wherein the first unit and the second unit perform clock synchronization while communication of the control unit is established, and the first unit performs a process to convert the output to the alternative control line to a PWM signal while communication of the control unit is interrupted.

6. The control unit is It is bus-connected via the aforementioned alternative control line, and it is possible to generate a PWM signal on the aforementioned alternative control line. The first unit and the second unit are, The electronic device according to claim 5, wherein the clock synchronization is performed by a PWM signal generated by the control unit.

7. Backplane and A control unit, which is the monitoring unit, is mounted on the backplane, A cooling method for an electronic device comprising a plurality of controlled units mounted on the backplane, the control device being monitored, The aforementioned backplane is The control unit includes a monitoring communication line for inter-unit communication between the control unit and the plurality of controlled units, and a bus-connected alternative control line. The plurality of controlled units are, It includes a first unit that is subject to high temperature protection and a second unit that drives a cooling fan, The aforementioned cooling method is The first unit performs a step of monitoring the status of the control unit, A method for cooling an electronic device, comprising the step of the first unit performing substitute control to operate the second unit using the alternative control line in place of the control unit, triggered by a communication interruption of the control unit.

8. A controlled unit to be monitored, which can be mounted on a backplane including a monitoring communication line for inter-unit communication and a bus-connected alternative control line, A circuit board having a connector that is mounted on the backplane, The circuit board includes a signal processing unit mounted on the circuit board, The signal processing unit, A controlled unit that, upon a communication failure of the monitoring control unit, sends a signal to the alternative control line to drive the cooling fan of another controlled unit.

9. A controlled unit to be monitored, which can be mounted on a backplane including a monitoring communication line for inter-unit communication and a bus-connected alternative control line, A circuit board having a connector that is mounted on the backplane, The signal processing unit mounted on the circuit board, The circuit board includes a cooling fan mounted on it, The signal processing unit, A controlled unit that drives the cooling fan based on a signal generated on the alternative control line by another controlled unit, triggered by a communication interruption of the control unit which is the primary monitoring unit.

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