JP2003309623A - Packet communication equipment and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible for a supply voltage or a supplied voltage to return to a desired voltage without needing that a cable is pulled out, and both power supplying side equipment and power receiving side equipment are raised again by power supply off/on, when power is supplied from equipment connected via the cable and a supplied power source voltage is decreased. <P>SOLUTION: This packet communication equipment (1) which is connected with external packet communication equipment via the cable and transmits and receives packets is provided with: a receptacle (105) to which power is supplied from the external packet communication equipment; power source monitoring equipment (111) for monitoring a voltage of the receptacle; and informing means (103, 110, 107, 106, 105) for informing decrease of the voltage to the external packet communication equipment, when the monitoring equipment decides that the voltage of the receptacle is lower than a prescribed voltage. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet communication device for transmitting and receiving packets via a transmission medium and a control method thereof, and more particularly to a packet communication device connected to a high performance serial bus defined as IEEE standard 1394 and its control. Regarding the method.

[0002]

2. Description of the Related Art In a high performance serial bus system defined as IEEE standard 1394,
A device connected to the bus is called a node. Furthermore, when a node is newly connected to or disconnected from the bus, a signal called bus reset is generated,
After exchanging predetermined signals, an identification number called a node ID is assigned to each node connected to the bus.

Further, in the high performance serial bus system defined as the IEEE standard 1394, communication is performed in units of data strings called packets. The packets include an isochronous packet for transferring data requiring real-time property and an asynchronous packet for transferring data not requiring real-time property. Isochronous packets are transferred by securing a certain band called a channel. The asynchronous packet includes a request packet for requesting data writing and reading to the partner device and a response packet for the received request packet.

There are 6-core and 4-core cables for connecting each node to form a high performance serial bus. Of the four-core cable, two cores transfer data, and the other two cores transfer a signal called strobe. The 6-core cable is the above 4-core cable with a power line and a ground line added. The power supply line and the ground line are for supplying or receiving power between nodes connected by a 6-core cable.

Some nodes have a function of supplying power to other nodes connected via a cable, and conversely receive power supply from another node connected via a cable to partially or entirely There is something to operate.

As an example of operating a part of a node with a power source which receives power via a cable, when a PHY / Link interface is connected through an isolation barrier, there is a case where only the PHY unit is powered by a power source which receives power via a cable. Conceivable. That is, the signal ground of the node and the ground of the PHY section are separated from each other to prevent a current from flowing due to a difference in potential difference from other nodes and an extra voltage from being applied to the Link and other portions. Also,
Since the PHY unit is operated by a power supply that receives power via a cable even when the power of the node itself is cut off, it is possible to transmit signals and packets even in a connection mode in which the above node has entered between other nodes with which it wants to communicate. Here, the PHY is a physical layer defined by the IEEE standard 1394, and has a packet / arbitration signal transmission / reception function, an encoding / decoding function, and the like. Generally composed of hardware. Li
nk is a link layer also defined by IEEE standard 1394, and is a part that adds a header or CRC to data to generate a packet, buffers the packet, and monitors the cycle time.

[0007]

However, when power is supplied from another node connected by a cable to operate part or all of the node, a short circuit of the cable, a disconnection of the power line, and a current However, there is a problem in that if the power supply voltage is lowered due to some reason such as an increase in power consumption, an abnormality occurs in the other node, or the like, it cannot operate. Also, for other nodes that are supplying power,
There was no means to notify that an abnormality occurred in the node. Further, in such a case, there is a problem that a node to which power is normally supplied is searched for to change the connection, or if there is no such connection, the connection must be given up and disconnected.

On the other hand, even when power is supplied to another node connected by a cable, if the power supply voltage drops due to some factor as described above, another node to which power is supplied is supplied. There was no way to let him know. As a result, the above-mentioned other nodes become inoperable, and there is a problem that either one of the nodes must be disconnected by disconnecting the cable and changing the connection, restarting the power supply of both nodes or restarting.

The present invention has been made in view of the above problems, and when power is supplied from a device connected via a cable and the supplied power supply voltage drops, a part of the device is provided. Or, it is possible to cope with the voltage drop before the whole becomes inoperable, pull out the cable, and turn off the power of both the power supply side and the power supply side.
A first object is to enable the supply voltage or the reception voltage to return to a desired voltage without turning on / ON and restarting.

Further, when power is supplied to a device connected via a cable, and when the power supply voltage being supplied is lowered, before a part or the whole of the device to which the power is supplied becomes inoperable. The supply voltage or the received voltage is restored to the desired voltage without disconnecting the cable and turning off / on the power supply and supply side devices to restart the device so that it can handle the voltage drop. The second purpose is to be able to do so.

[0011]

The present invention has been made in view of the above problems, and in order to achieve the first object, it is connected to an external packet communication device via a cable and A packet communication device of the present invention for transmitting and receiving, a power supply means for receiving power from the external packet communication device, a monitoring means for monitoring the voltage of the power supply means,
When the monitoring means determines that the voltage of the power supply means is lower than a predetermined voltage, the monitoring means has a notification means for notifying the external packet communication device of the voltage drop.

Further, it has a power supply means for receiving power from an external packet communication device connected through a cable,
A control method of a packet communication device of the present invention for transmitting / receiving a packet to / from the external packet communication device includes a monitoring step of monitoring a voltage of the power supply means, and a voltage of the power supply means being smaller than a predetermined voltage in the monitoring step. And a notification step of notifying the external packet communication device of the voltage drop when the determination is made.

According to another aspect, the packet communication device of the present invention, which is connected to an external packet communication device via a cable and transmits / receives packets, is a first packet power supply device which receives power from the external packet communication device. Power source means, monitoring means for monitoring the voltage of the first power source means, and initialization of the communication path when the monitoring means determines that the voltage of the first power source means is lower than a predetermined voltage. Reset means.

A packet communication device control method according to the present invention, further comprising first power supply means for receiving power from an external packet communication device connected via a cable, for transmitting / receiving packets to / from the external packet communication device. Is the first
Of the power source means, and a reset step of initializing the communication path when the voltage of the first power source means is determined to be lower than a predetermined voltage in the monitoring step.

According to another aspect, the packet communication device is connected to an external packet communication device via a cable and transmits / receives a packet, the first power supply means comprising:
Second power supply means that receives power from the external packet communication device, monitoring means that monitors the voltage of the second power supply means, and the monitoring means that the voltage of the second power supply means is smaller than a predetermined voltage. And a switching means for switching the power supply by the second power supply means to the first power supply means.

A book for transmitting and receiving packets to and from the external packet communication device, which has a first power supply device and a second power supply device which receives power from an external packet communication device connected via a cable. A control method for a packet communication device according to the present invention comprises: a monitoring step of monitoring a voltage of the second power supply means; and a step of monitoring the voltage of the second power supply means when the monitoring step determines that the voltage of the second power supply means is lower than a predetermined voltage. And a switching step of switching the power supply by the second power supply means to the first power supply means.

In order to achieve the second object,
A packet communication device of the present invention, which is connected to an external packet communication device via a cable and transmits / receives packets, has a power supply unit that supplies power to the external packet communication device, and a monitoring unit that monitors the voltage of the power supply unit. When the monitoring means determines that the voltage of the power supply means is lower than a predetermined voltage, the monitoring means has a notification means for notifying the external packet communication device of the voltage drop.

Further, it has power supply means for receiving power from an external packet communication device connected via a cable,
A control method of a packet communication device of the present invention for transmitting / receiving a packet to / from the external packet communication device includes a monitoring step of monitoring a voltage of the power supply means, and a voltage of the power supply means being smaller than a predetermined voltage in the monitoring step. And a notification step of notifying the external packet communication device of the voltage drop when the determination is made.

According to another aspect, the packet communication device of the present invention, which is connected to an external packet communication device via a cable and transmits / receives packets, includes a power supply means for supplying power to the external packet communication device. It has a monitoring means for monitoring the voltage of the power supply means, and a reset means for initializing the communication path when the monitoring means judges that the voltage of the power supply means is lower than a predetermined voltage.

A packet communication device control method according to the present invention, further comprising first power supply means for receiving power from an external packet communication device connected via a cable, for transmitting / receiving packets to / from the external packet communication device. Is the first
Of the power source means, and a reset step of initializing the communication path when the voltage of the first power source means is determined to be lower than a predetermined voltage in the monitoring step.

[0021]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

(First Embodiment) FIG. 1 is a schematic block diagram of a packet communication device according to a first embodiment of the present invention. In the figure, 1 is a packet communication device, and 10
Reference numeral 1 is a control device for controlling each part of the packet communication device 1 in accordance with program instructions stored in a ROM 102, 102 is a ROM (Read Only Memory) in which program instruction codes, unique data, etc. are stored in advance, and 103 is a control device. A RAM (Randum Access) 101 in which data is written or read as needed, and packet data is transferred (read when packet is transmitted and is written when packet is received) by a DMAC 110 described later.
Memory), 104 is 6 based on IEEE standard 1394
A core cable, 105 is a 6-pin receptacle conforming to the IEEE standard 1394 for connecting one end of the cable 104 to the packet communication device. The other end of the cable 104 is connected to a second packet communication device (not shown). Further, it is assumed that the second packet communication device supplies power to a device connected through the cable 104, that is, the packet communication device 1.

Reference numeral 106 denotes a portion that controls a physical layer defined by the IEEE standard 1394, and is configured by connecting an LSI generally called PHY and passive components around the LSI.
Hereinafter referred to as PHY section. Reference numeral 107 denotes a part that controls the link layer, and generally includes hardware called Link and a FIFO (First In First Ou) that temporarily stores a transmission / reception packet.
It is composed of a buffer memory 108 called t). Hereinafter, it is simply referred to as a Link part. It is assumed that the PHY unit 106 and the Link unit 107 are AC-connected through the isolation barrier circuit 109. 110 is DMA (Direc
t Memory Access) controller for directly transferring the data of the transmission packet and the reception packet between the RAM 103 and the FIFO 108 without passing through the control device 101, and at the time of packet transmission, from a designated area of the RAM 103. Transmission FIFO of the FIFO 108
When the packet is received, it operates to transfer all or a part of the packet from the receiving FIFO of the FIFO 108 to the designated area of the RAM 103.

Reference numeral 111 denotes a voltage monitoring device, which is a cable 1
It is for monitoring the voltage of the power source received from the second packet communication device through 04, and outputs different signals depending on whether it is below a predetermined voltage or exceeds a predetermined voltage. 112 is a power supply switching device,
According to an instruction from the control device 101 via the input / output port 115, the power supplied to the regulator 113 is set to the power supplied from the second packet communication device through the cable 104, or the output of the AC / DC converter 114. To switch to. Reference numeral 113 is a regulator, which converts the output voltage of the switching device 112 into a voltage necessary for the PHY unit to operate and supplies a current.

Reference numeral 114 denotes an AC / DC converter, which receives a commercial AC power source as input, converts it into a DC power source required for each block, and outputs it. In the packet communication device 1, AC / D
It is assumed that the output of the C converter 114 causes each unit other than the PHY unit 106 and the regulator 113 to operate. Further, as described above, the output of the AC / DC converter 114 is input to the regulator 113 depending on the switching device 112. That is, the AC / DC converter 114 has two systems of D
C has a power supply output function, and one system is a power supply for operating each block. In this embodiment, the voltage is DC3.
Set to 3V. The other one system is a power source for operating the PHY unit 106 by inputting it to the regulator 113 through the switching device 112, and in the present embodiment, the voltage is DC1.
Set to 0V.

Reference numeral 115 denotes an input / output port, which is the voltage monitoring device 1
It plays a role of transmitting the output signal of 11 to the control device 101 and a role of transmitting the instruction of the control device 101 to the switching device 112. Reference numeral 116 denotes an internal bus, the control device 101, the ROM
102, RAM 103, Link unit 107, DMAC1
10 and the input / output port 115 are connected. 117 is AC
A plug that is installed in the office or home
AC power is input to the AC / DC converter 114 by connecting the AC plug 117 to the C outlet.

FIG. 2 is a flow chart for explaining the operation of the packet communication device 1 according to the first embodiment having the above configuration. Hereinafter, description will be given according to the flowchart of FIG.

The packet communication device 1 is composed of the cable 1
It is assumed that power is supplied from a second packet communication device (not shown) connected at 04, and the PHY unit 106 is supplied with power via the switching device 112 and the regulator 113. In the first embodiment, it is assumed that the second packet communication device supplies power to the packet communication device 1 through the cable 104 at a voltage of 12V.

First, in step S101, the voltage monitoring device 111 monitors the voltage (hereinafter abbreviated as VP) supplied from the second packet communication device, and then in step S101.
At 102, it is determined whether VP is less than or equal to a predetermined voltage. For example, if the power supply voltage required for the PHY unit 106 to operate is 3.3V and the input voltage required for the regulator 113 to output 3.3V is 7V or higher, for example, if VP is 8V or lower, Determine if there is.

The reason why the voltage is not set to 7 V is that the voltage monitoring device 111 notifies the control device 101 through the input / output port 115 that the power supply voltage has dropped after VP has become 7 V or less. Since 3.3V, which is necessary for this, cannot be output already, PH
This is because the Y section 106 may be in an inoperable state. Therefore, in this case, it is necessary to set a voltage value higher than 7 V to the above-mentioned predetermined voltage. Therefore, in the first embodiment, the predetermined voltage is set to 8V.

Since the power supply voltage supplied by the second packet communication device is 12V, normally VP ≧ 8V (NO in step S102). In this state, the PHY unit 106 is operable, and the PHY unit 106 or the second packet communication device or IEEE
It is possible to communicate with other packet communication devices connected on the same serial bus defined by E standard 1394. In this case, the process returns to step S101, and the voltage monitoring device 111 continues to monitor the power supply voltage.

On the other hand, the power supply voltage supplied by the second packet communication device drops for some reason and the voltage monitoring device 111
Is determined to be VP <8V, and a signal indicating that is output to the input / output port 115 (Y in step S102).
ES), the control device 101 sends the same signal to the input / output port 115.
Read from the RAM and DM a predetermined packet from the RAM 103
It is transmitted to the second packet communication device via the AC 110, the link unit 107, the PHY unit 106, the receptacle 105, and the cable 104 (step S103). When transmitting the above predetermined packet as an asynchronous packet,
Transmission is generally performed by a method called a split transaction, and in this case, a response packet from the partner device that transmitted the packet is waited for. While waiting for the response packet, the split timer provided in the Link unit is activated, and if the response packet is not received before the split timer times out (NO in step S104, YES in step S105), the process returns to step S103 to perform the above. Resend a given packet. If the response packet is received before the split timer times out (YES in step S104), the series of processes is terminated and the process returns to step S101.

When the predetermined packet is transmitted in step S103, instead of transferring the packet data from the RAM 103 to the Link unit 107 by the DMAC 110,
There is also a method of writing the packet data in the register of the Link unit 107 and transmitting the packet data.

As described above, according to the first embodiment, P
It becomes possible to notify the second packet communication device that the supply voltage has dropped before the HY unit 106 becomes inoperable.

(Second Embodiment) Next, the second embodiment of the present invention will be described.
The embodiment will be described.

In the second embodiment as well, the packet communication device having the configuration described with reference to FIG. 1 in the first embodiment is used, and the description is omitted.

FIG. 3 is a flow chart for explaining the operation of the packet communication device 1 having the configuration shown in FIG. 1 in the second embodiment of the present invention.

Similar to the first embodiment, the packet communication device 1 has a second connection (not shown) connected by a cable 104.
Power is supplied from the packet communication device of the PHY unit 10 via the switching device 112 and the regulator 113.
It is assumed that the power supply for 6 is covered. Further, similarly to the first embodiment, the power supply voltage VP supplied from the second packet communication device is 12V and the predetermined voltage is 8V.

In step S201, the voltage monitoring device 111
Monitors VP, and VP is 8V in step S202.
It is determined whether it is below or exceeds 8V. When VP exceeds 8V (NO in step S202), the PHY unit 10
6 is operable, the second packet communication device or I
It is possible to communicate with another packet communication device connected on the same serial bus defined by EEE standard 1394. On the other hand, when the voltage monitoring device 111 determines that VP ≦ 8V (YES in step S202), it outputs a signal to that effect to the input / output port 115, and the control device 101 reads the same signal from the input / output port 115 and a predetermined signal is output. The PHY unit 106 is instructed to output the level signal to the cable 104 via the Link unit 107 (step S20).
3).

As described above, according to the second embodiment,
By changing the signal level of the serial bus defined by the IEEE standard 1394 instead of the packet, it is possible to directly notify the second packet communication device connected by the cable 104 of the abnormality without exchanging the packet. It will be possible.

(Third Embodiment) Next, the third embodiment of the present invention will be described.
The embodiment will be described.

In the third embodiment as well, the packet communication device having the configuration described with reference to FIG. 1 in the first embodiment is used, and the description thereof will be omitted.

FIG. 4 is a flow chart for explaining the operation of the packet communication device 1 having the configuration shown in FIG. 1 in the third embodiment of the present invention.

Similar to the first embodiment, the packet communication device 1 is provided with a second cable (not shown) connected by a cable 104.
Power is supplied from the packet communication device of the PHY unit 10 via the switching device 112 and the regulator 113.
It is assumed that the power supply for 6 is covered. Further, similarly to the first embodiment, the power supply voltage VP supplied from the second packet communication device is 12V and the predetermined voltage is 8V.

In step S301, the voltage monitoring device 111
Monitors VP, and VP is 8V in step S302.
It is determined whether it is below or exceeds 8V. When VP exceeds 8V (NO in step S302), the PHY unit 10
6 is operable, the second packet communication device or I
It is possible to communicate with another packet communication device connected on the same serial bus defined by EEE standard 1394. On the other hand, when the voltage monitoring device 111 determines that VP ≦ 8 V (YES in step S302), it outputs a signal to that effect to the input / output port 115, and the control device 101 reads the same signal from the input / output port 115 and the switching device. 112
Control the input to the regulator 113 from VP to A
The output is switched to the output of the C / DC converter 114 (step S303). The output voltage from the AC / DC converter 114 to the switching device 112 is 10V as described above,
It may be 8 V or more.

As a result, the AC / DC converter 114
The DC output of is converted to 3.3V by the regulator 113,
Since it is supplied to the PHY unit 106, the PHY unit 1
The power supply of No. 06 is stable, and subsequent communication can be performed (step S304).

As described above, according to the third embodiment, it is possible to continue the communication even when the supply voltage from the second packet communication device drops.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described.
The embodiment will be described.

In the fourth embodiment as well, the packet communication device having the configuration described with reference to FIG. 1 in the first embodiment is used, and the description will be omitted.

FIG. 5 is a flow chart for explaining the operation of the packet communication device 1 having the configuration shown in FIG. 1 in the fourth embodiment of the present invention.

Similar to the first embodiment, the packet communication device 1 has a second connection (not shown) connected by a cable 104.
Power is supplied from the packet communication device of the PHY unit 10 via the switching device 112 and the regulator 113.
It is assumed that the power supply for 6 is covered. Further, similarly to the first embodiment, the power supply voltage VP supplied from the second packet communication device is 12V and the predetermined voltage is 8V.

In step S401, the voltage monitoring device 111
Monitors VP, and VP is 8V in step S402.
It is determined whether it is below or exceeds 8V. When VP exceeds 8V (NO in step S402), the PHY unit 10
6 is operable, the second packet communication device or I
It is possible to communicate with another packet communication device connected on the same serial bus defined by EEE standard 1394. On the other hand, when the voltage monitoring device 111 determines that VP ≦ 8 V (YES in step S402), it outputs a signal to that effect to the input / output port 115, the control device 101 reads the signal from the input / output port 115, and the link unit 10
7, a signal called a bus reset is generated in the cable 104 via the PHY unit 106 and the receptacle 105 (step S403). A signal called bus reset is transmitted to all the nodes connected by the IEEE1394 cable, and the node ID is secured again. Some nodes initialize some or all parts of the node by bus reset.

When the second packet communication device initializes the power supply unit by this bus reset and supplies power again with a normal voltage, the voltage monitoring device 111 changes the output signal to the normal output signal. You can

As described above, according to the fourth embodiment,
It can be expected that the voltage returns to normal when the second packet communication device supplying power to the cable 104 initializes the supply circuit or the like.

If the voltage monitoring device 111 determines that VP ≦ 8V even after the bus reset is generated, the control device 101 controls the regulator 113 as described in the eight major embodiments. Input VP to AC / D
By switching to the output of the C converter 114,
It is possible to continue communication more reliably.

Further, in the first to fourth embodiments, VP is compared with 8V, but the present invention is not limited to 8V, and the power supply voltage required for the PHY unit 106 to operate is output. In order to do so, the voltage may be set higher than the voltage required by an arbitrary voltage.

(Fifth Embodiment) FIG. 6 is a schematic block diagram of a packet communication device according to a fifth embodiment of the present invention. In the figure, 6 is a packet communication device, 60
Reference numeral 1 is a control device for controlling each part of the packet communication device 6 according to a program command stored in a ROM 602, 602 is a ROM (Read Only Memory) in which a program command code, unique data, etc. are stored in advance, and 603 is a control device. A RAM (Randum Access) 601 performs writing and reading of data as necessary, and packet data transfer (reading during packet transmission and writing during packet reception) is performed by a DMAC 610 described later.
Memory), 604 is based on IEEE standard 1394 6
A core cable, 605, is a 6-pin receptacle conforming to the IEEE standard 1394 for connecting one end of the cable 604 to the packet communication device. The other end of the cable 604 is connected to a second packet communication device (not shown). The second packet communication device receives power from the device connected through the cable 604, that is, the packet communication device 6.

Reference numeral 606 is a portion that controls a physical layer defined by the IEEE standard 1394, and is constituted by connecting an LSI generally called PHY and passive components around the LSI.
Hereinafter referred to as PHY section. Reference numeral 607 denotes a part that controls the link layer, which is generally called Link and a FIFO (First In First Ou) that temporarily stores a transmission / reception packet.
The buffer memory 608 is called t). Hereinafter, it is simply referred to as a Link part. The connection and signal between the PHY unit 606 and the Link unit 607 are called a PHY / Link interface, and the method of AC connection through the isolation barrier and the method of direct DC connection are defined. 609 is P by DC connection
It is a HY / Link interface. 610 is DM
A (Direct Memory Access) controller, RAM
This is for directly transferring the data of the transmission packet and the reception packet between the 603 and the FIFO 608 without passing through the control device 601, and the RAM 6 at the time of packet transmission.
03, from the designated area to the transmission FIFO of the FIFO 608, and when receiving the packet, the reception FIFO of the FIFO 608 operates to transfer all or part of the packet to the designated area of the RAM 603.

Reference numeral 611 denotes a voltage monitoring device, which is a cable 6
It is for monitoring the voltage of the power source received from the second packet communication device through 04, and outputs different signals depending on whether it is below a predetermined voltage or exceeds a predetermined voltage. 612 is an overcurrent protection device,
It has a function of operating when the current supplied from the output of an AC / DC converter 614, which will be described later, to the cable 604 exceeds a predetermined value and interrupting the current.

An AC / DC converter 614 receives a commercial AC power source as an input, converts it into a DC power source required for each block, and outputs it. In the packet communication device 6, AC / D
It is assumed that each unit operates with the output of the C converter 614. In addition, AC is provided to the power supply terminal of the receptacle 605.
The output of the / DC converter 614 is input. That is, A
The C / DC converter 614 has a two-system DC power supply output function, and one system is a power supply for operating each block. In this embodiment, the voltage is DC 3.3V. The other one system is a power supply for supplying the second packet communication device through the cable 604, and the voltage is DC 20 V in this embodiment.

Reference numeral 615 denotes an input / output port, which is the voltage monitoring device 6
It takes the role of transmitting the output signal of 11 to the control device 601. Reference numeral 616 denotes an internal bus, which is a control device 601.
ROM 602, RAM 603, Link unit 607, DM
The AC 610 and the input / output port 615 are connected. 617
Is an AC plug, and AC power is input to the AC / DC converter 614 by connecting the AC plug 617 to an AC outlet installed in an office or home.

FIG. 7 is a flow chart for explaining the operation of the packet communication device 6 having the above-mentioned configuration according to the fifth embodiment. Hereinafter, description will be given according to the flowchart of FIG.

First, when the packet communication device 6 is activated,
The AC / DC converter 614 starts to supply DC 3.3V power to each unit, and the control device 601 sets each unit to a state necessary for operation according to the program code stored in the ROM 602. At the same time, the AC / DC converter 61
The DC 24 V output of No. 4 is input to the receptacle 605 through the overcurrent protection device 611 and is supplied to the second packet communication device (not shown) through the cable 604. The second packet communication device converts the 24V DC power supply supplied through the cable 604 into a required voltage internally and operates a part of the second packet communication device or the entire second packet communication device. To use.

In the above state, the voltage of the power supply supplied in step S701 (hereinafter abbreviated as VP) is
It is monitored by the voltage monitoring device 611, and step S702
Then, it is determined whether VP is equal to or lower than a predetermined voltage. In the fifth embodiment, the predetermined voltage is 10V.

The AC / DC converter 614 supplies the second DC 24V output via the cable 604, so
Normally, VP> 10V. In this state, the voltage monitoring device 611 is regarded as normal (N in step S702).
O), a signal indicating normal is output to the input port 615. In this case, the second packet communication device is considered to be able to communicate with the packet communication device 6 or another packet communication device connected to the same serial bus defined by the IEEE standard 1394.

On the other hand, if the power supply voltage supplied from the AC / DC converter 614 drops for some reason and the voltage monitoring device 611 determines that VP ≦ 10 V (YES in step S702), VP falls below a predetermined voltage. A signal indicating that it has become available is output to the input port 615. The control device 601 reads the same signal from the input port 115, and sends a predetermined packet from the RAM 603 to the DMAC 610, Lin.
It is transmitted to the second packet communication device via the k unit 607, the PHY unit 606, the receptacle 605, and the cable 604 (step S703). As described in the first embodiment, when the above-mentioned predetermined packet is transmitted as an asynchronous packet, it is general that the predetermined packet is transmitted by a method called a split transaction. Wait for a response packet from the second packet communication device. Li while waiting for a response packet
If the split timer provided in the nk unit is started and the response packet is not received from the second packet communication device before the split timer times out (step S
(No in 704, YES in step S705), returns to step S703, and retransmits the predetermined packet. If a response packet is received from the second packet communication device before the split timer times out (step S
(YES in 704), ends the series of processes, and returns to step S7.
Return to 01.

When transmitting a predetermined packet in step S703, instead of transferring the packet data from the RAM 603 to the Link unit 607 by the DMAC 610,
There is also a method of writing packet data in the register of the link unit 607 and transmitting the packet data.

As described above, according to the fifth embodiment, the second
It is possible to notify the second packet communication device that the supply voltage has dropped before the second packet communication device becomes inoperable.

(Sixth Embodiment) Next, the sixth embodiment of the present invention will be described.
The embodiment will be described.

In the sixth embodiment as well, the packet communication device having the configuration described in the fifth embodiment with reference to FIG. 6 is used, and the description thereof will be omitted. FIG. 8 is a flowchart for explaining the operation of the packet communication device 6 having the configuration shown in FIG. 6 in the sixth embodiment of the present invention.

Similar to the fifth embodiment, the packet communication device 6 has a second connection (not shown) connected by a cable 604.
Power is supplied to the packet communication device. Also,
Similar to the fifth embodiment, the power supply voltage VP supplied to the second packet communication device is set to 24V and the predetermined voltage is set to 10V.

In step S801, the voltage monitoring device 611.
Monitors the VP, and in step S802, the VP is 10
It is judged whether it is less than V or exceeds 10V. VP is 1
If it exceeds 0 V (NO in step S802), the second packet communication device is the packet communication device 6 or IEEE.
The voltage monitoring device 611 outputs a signal indicating normal to the input port 615, considering that it is possible to communicate with another packet communication device connected to the same serial bus defined by the standard 1394. .

On the other hand, the voltage monitoring device 611 determines that VP ≦ 10V.
(YES in step S802), a signal indicating that VP has become equal to or lower than the predetermined voltage is input port 615.
Then, the control device 601 reads the content of the signal from the input / output port 615, and outputs a predetermined level signal to the cable 6
04 to output to PHY via Link unit 607.
The unit 606 is instructed (step S803).

As described above, according to the sixth embodiment,
By changing the signal level of the serial bus specified by IEEE standard 1394 instead of the packet, the power supply voltage being supplied to the second packet communication device connected by the cable 604 without exchanging packets. It is possible to directly notify the abnormality of.

(Seventh Embodiment) Next, the seventh embodiment of the present invention will be described.
The embodiment will be described.

Also in the seventh embodiment, the packet communication device having the configuration described in the fifth embodiment with reference to FIG. 6 is used, and the description thereof is omitted.

FIG. 9 is a flow chart for explaining the operation of the packet communication device 6 having the configuration shown in FIG. 6 in the seventh embodiment of the present invention.

Similar to the fifth embodiment, the packet communication device 6 is provided with a second connection (not shown) connected by a cable 604.
Power is supplied to the packet communication device. Further, similarly to the fifth embodiment, the power supply voltage VP supplied to the second packet communication device is 24V and the predetermined voltage is 10V.
And

In step S901, the voltage monitoring device 611
Monitors the VP, and in step S902, the VP is 10
It is judged whether it is less than V or exceeds 10V. VP is 1
If it exceeds 0 V (NO in step S902), the second packet communication device is the packet communication device 6 or IEEE.
The voltage monitoring device 611 outputs a signal indicating normal to the input port 615, considering that it is possible to communicate with another packet communication device connected to the same serial bus defined by the standard 1394. .

On the other hand, when the voltage monitoring device 611 is VP ≦ 10V
(YES in step S902), a signal indicating that VP has become less than the predetermined voltage is input port 615.
Then, the control device 601 reads the content of the same signal from the input / output port 615, and the link unit 607 and the PHY unit 6
06, a signal called a bus reset is generated in the cable 604 via the receptacle 605 (step S9).
03). A signal called bus reset is IEEE13
It is transmitted to all the nodes connected by the 94 cable, and the node ID is secured again. Some nodes initialize some or all parts of the node by bus reset.

It is assumed that the bus reset causes the second packet communication device to convert the power received through the cable 604 into a voltage or the like required internally, and the bus reset initializes the power receiving unit or the converting unit. If VP is 10 V or less due to the second packet communication device, a bus reset may cause the VP to return to the original voltage. Therefore, in step S904, the voltage monitoring device 611 monitors the VP after reset, and when the VP exceeds the predetermined voltage (NO in step S905), the output signal of the voltage monitoring device 611 returns to a signal indicating that it is normal. Control device 601
If it recognizes that the voltage has returned to the normal state via the input / output port 615, it is possible to perform normal packet communication while causing the voltage monitoring device 611 to monitor the supply voltage.

Even after the bus reset is generated, the voltage monitoring device 611 determines that VP ≦ 10V (YES in step S905), and the control device 601 causes the input port 61 to operate.
When it is recognized from 5, the control device 601 again generates a signal called a bus reset on the cable 604 via the Link unit 607, the PHY unit 606, and the receptacle 605 (step S906). After the bus reset, each node transmits a packet called a self ID packet. The self-ID packet includes the ID number obtained by the self-node, the connection status of each port, and information regarding the power supply. Here, in the self ID packet to be transmitted, information indicating that the power source information section supplies power to the cable, and information that neither power is supplied to the cable 604 nor received from the cable 604. By changing to and transmitting (step S90
7), a method of urging the second packet communication device to stop receiving power from the cable 604 can be considered.

Further, instead of generating the bus reset in step S903, the P connected by the cable 604 is connected.
The ports of the HY unit 606 or all the ports of the second packet communication device are put in the suspend state, and step S90
4. In S905, when it is determined that the voltage has returned to the predetermined voltage or higher, the suspended port may be resumed. If all the ports of the second packet communication device are suspended, it can be expected that the power supply voltage supplied through the cable 604 will be restored.

As described above, according to the seventh embodiment, the main power source of the packet communication device 6 and the second packet communication device is turned off and on again, and the cable 604 connected to the second packet communication device is disconnected. This has the effect of increasing the possibility that the power supply will return to normal without being removed.

In the embodiment of the present invention described above,
AC / DC converter 114 or 614
Although the AC power source is input from the plug 117 or 617 to obtain the required power source, a battery or a battery may be provided instead, and the required power source may be obtained from the battery or the battery. In addition, it has an AC / DC converter, an AC plug, and a battery or a battery.
The device may switch between using the output from the C / DC converter and using the output from the battery or the battery.

Although the PHYs 106 and 606 have only one port connected to the receptacles 105 and 605, respectively, the present invention can be applied even if they have two ports or three ports.

Further, in the above fifth to seventh embodiments, VP is compared with 10V, but the present invention is not limited to 10V, and is higher than the voltage considered necessary in the second packet communication device. The voltage may be increased by an arbitrary voltage.

[0088]

Other Embodiments The present invention may be applied to a system including a plurality of devices or an apparatus including a single device.

Further, an object of the present invention is to supply a storage medium (or recording medium) recording a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer of the system or apparatus ( Alternatively, by the CPU or MPU) reading and executing the program code stored in the storage medium,
It goes without saying that it will be achieved. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.
Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also based on the instruction of the program code,
An operating system (OS) running on the computer does some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized. Here, examples of the storage medium for storing the program code include a flexible disk, a hard disk, a ROM, a RAM, a magnetic tape, a non-volatile memory card, a CD-ROM, and a C.
DR, DVD, optical disk, magneto-optical disk, MO, etc. are considered.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized.

When the present invention is applied to the above-mentioned storage medium, the storage medium includes the previously described FIGS. 2 to 5 and 6.
The program code corresponding to the flowchart shown in any one of FIG. 9 or a combination thereof is stored.

[0092]

As described above, according to the present invention, when power is supplied from a device connected via a cable and the supplied power supply voltage drops, a part or the whole of the device is obtained. By responding to the voltage drop before the power supply becomes inoperable, without disconnecting the cable or powering on / off the power supply side and power supply side both devices, the supply voltage or The received voltage can be returned to a desired voltage.

Further, when power is supplied to a device connected via a cable and the power supply voltage being supplied is lowered, before a part or the whole of the device to which the power is supplied becomes inoperable. Corresponding to the voltage drop, the supply voltage or the receiving voltage can be restored to the desired voltage without pulling out the cable or turning the power on / off of both the power supply side and the power supply side. Can be made.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a packet communication device according to first to fourth embodiments of the present invention.

FIG. 2 is a flowchart showing an operation in the first exemplary embodiment of the present invention.

FIG. 3 is a flowchart showing an operation in the second embodiment of the present invention.

FIG. 4 is a flowchart showing an operation in the third embodiment of the present invention.

FIG. 5 is a flowchart showing an operation in the fourth embodiment of the present invention.

FIG. 6 is a schematic block diagram of a packet communication device according to fifth to seventh embodiments of the present invention.

FIG. 7 is a flowchart showing an operation according to the fifth embodiment of the present invention.

FIG. 8 is a flowchart showing an operation in the sixth embodiment of the present invention.

FIG. 9 is a flowchart showing an operation in the seventh embodiment of the present invention.

[Explanation of symbols]

1,6 Packet communication device 101,601 control device 102,602 ROM 103,603 RAM 104,604 cable 105,605 Receptacle 106,606 PHY section 107,607 Link section 108,608 FIFO 109,609 PHY / Link interface 110,610 DMAC 111,611 Voltage monitoring device 112 Switching device 113 regulator 114,614 AC / DC converter 115,615 I / O ports 116,616 Internal bus 117,617 AC plug 612 Overcurrent protection device

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5B077 NN02                 5K033 DA11 DB25 EA06 EA07 EB06                       EC01                 5K035 AA04 AA06 BB01 DD01 EE04                       JJ05                 5K042 AA03 BA10 CA04 CA13 EA03                       JA01 KA03 KA04                 5K046 BA05 BB05 HH73 PP01 ZZ11

Claims (32)

[Claims] 1. A packet communication device connected to an external packet communication device via a cable for transmitting and receiving packets, comprising: a power supply unit that receives power from the external packet communication device; and a voltage of the power supply unit. Packet communication comprising: a monitoring unit for controlling the external packet communication device and a notification unit for notifying the external packet communication device of the voltage drop when the monitoring unit determines that the voltage of the power supply unit is lower than a predetermined voltage. apparatus. 2. The packet communication device according to claim 1, wherein the notifying unit transmits a predetermined packet to the external packet communication device. 3. The notifying means retransmits the predetermined packet when a response packet to the predetermined packet is not received from the external packet communication device within a predetermined time. The packet communication device described. 4. The packet communication device according to claim 1, wherein the notification means transmits a predetermined level signal. 5. A packet communication device connected to an external packet communication device via a cable for transmitting and receiving packets, comprising: first power supply means for receiving power from the external packet communication device; It has a monitoring means for monitoring the voltage of the power supply means, and a reset means for initializing the communication path when the monitoring means determines that the voltage of the first power supply means is lower than a predetermined voltage. Packet communication device. 6. The second power supply means and the first power supply means when the monitoring means determines that the voltage of the first power supply means is smaller than a predetermined voltage even after resetting by the reset means. The packet communication device according to claim 5, further comprising switching means for switching power supply to the second power supply means. 7. A packet communication device connected to an external packet communication device via a cable for transmitting and receiving packets, the first power supply means and a second power supply receiving power from the external packet communication device. Means, monitoring means for monitoring the voltage of the second power supply means, and power supplied from the second power supply means when the monitoring means determines that the voltage of the second power supply means is lower than a predetermined voltage. A packet communication device comprising: switching means for switching the supply to the first power supply means. 8. The predetermined voltage is a voltage value higher than a voltage value at which at least a part of the packet communication device may become inoperable. Packet communication device. 9. A packet communication device connected to an external packet communication device via a cable for transmitting and receiving packets, comprising: a power supply unit for supplying power to the external packet communication device; and a voltage of the power supply unit. A packet communication device, comprising: monitoring means; and notifying means for notifying the external packet communication device of a decrease in voltage when the monitoring means determines that the voltage of the power supply means is lower than a predetermined voltage. . 10. The packet communication device according to claim 9, wherein the notification means transmits a predetermined packet to the external packet communication device. 11. The notifying means resends the predetermined packet when a response packet to the predetermined packet is not received from the external packet communication device within a predetermined time. The packet communication device described. 12. The packet communication device according to claim 9, wherein the notifying unit transmits a predetermined level signal. 13. A packet communication device connected to an external packet communication device via a cable for transmitting and receiving packets, comprising: a power supply means for supplying power to the external packet communication equipment; and a voltage of the power supply means. A packet communication device comprising: a monitoring unit and a reset unit that initializes a communication path when the monitoring unit determines that the voltage of the power supply unit is lower than a predetermined voltage. 14. The predetermined voltage is a voltage value higher than a voltage value at which at least a part of the external packet communication device may become inoperable. The packet communication device described. 15. The packet communication device and the external packet communication device are connected by a serial bus defined by IEEE standard 1394.
15. The packet communication device according to any one of 14 to 14. 16. A method of controlling a packet communication device, comprising: a power supply unit that receives power from an external packet communication device connected via a cable, and transmitting and receiving packets to and from the external packet communication device. A monitoring step of monitoring the voltage of the means, and a notification step of notifying the external packet communication device of the voltage drop when the monitoring step determines that the voltage of the power supply means is lower than a predetermined voltage. Characteristic control method. 17. The control method according to claim 16, wherein in the notifying step, a predetermined packet is transmitted to the external packet communication device. 18. The method according to claim 17, further comprising a resending step of resending the predetermined packet when a response packet to the predetermined packet is not received from the external packet communication device within a predetermined time. The described control method. 19. The control method according to claim 16, wherein in the notifying step, a predetermined level signal is transmitted. 20. A method of controlling a packet communication device, comprising first power supply means for receiving power supply from an external packet communication device connected via a cable, and transmitting and receiving packets to and from the external packet communication device. A monitoring step of monitoring the voltage of the first power source means, and a reset step of initializing a communication path when the monitoring step determines that the voltage of the first power source means is lower than a predetermined voltage. A control method comprising: 21. The packet communication device further comprises a second power supply means, the step of monitoring the voltage of the first power supply means after the resetting by the reset step, and the first power supply means after the resetting. 21. The control method according to claim 20, further comprising a switching step of switching the power supply by the first power supply means to the second power supply means when the voltage of is smaller than a predetermined voltage. 22. A packet having a first power supply means and a second power supply means for receiving power from an external packet communication device connected via a cable, and transmitting and receiving a packet to and from the external packet communication device. A method of controlling a communication device, comprising: a monitoring step of monitoring a voltage of the second power supply means; and a step of monitoring the voltage of the second power supply means when the voltage of the second power supply means is lower than a predetermined voltage in the monitoring step. And a switching step of switching the power supply from the second power supply means to the first power supply means. 23. The predetermined voltage is a voltage value higher than a voltage value at which at least a part of the packet communication device may become inoperable.
23. The control method according to any one of 22 to 22. 24. A control method of a packet communication device, comprising: a power supply means for supplying power to an external packet communication device connected via a cable, and transmitting / receiving a packet to / from the external packet communication device, And a notification step of notifying the external packet communication device of the voltage drop when it is determined that the voltage of the power supply unit is lower than a predetermined voltage in the step. 25. The control method according to claim 24, wherein in the notifying step, a predetermined packet is transmitted to the external packet communication device. 26. The method according to claim 25, further comprising a resending step of resending the predetermined packet when a response packet to the predetermined packet is not received from the external packet communication device within a predetermined time. The described control method. 27. The control method according to claim 24, wherein in the notifying step, a predetermined level signal is transmitted. 28. A method of controlling a packet communication device, comprising: a power supply means for supplying electric power to an external packet communication device connected via a cable; and a packet communication device control method for transmitting / receiving packets to / from the external packet communication device. A control method comprising: a monitoring step of monitoring the voltage of the means, and a reset step of initializing the communication path when the voltage of the power supply means is determined to be lower than a predetermined voltage in the monitoring step. . 29. The predetermined voltage is a voltage value higher than a voltage value at which at least a part of the external packet communication device may become inoperable. The described control method. 30. The packet communication device and the external packet communication device are connected by a serial bus defined by IEEE standard 1394.
The control method according to any one of 6 to 29. 31. A program executable by an information processing device, having a program code for implementing the control method according to claim 16. 32. A storage medium storing the program according to claim 31.