WO2006137492A1

WO2006137492A1 - Network adapter, communication terminal, communication path distribution method, and program thereof

Info

Publication number: WO2006137492A1
Application number: PCT/JP2006/312533
Authority: WO
Inventors: Kazunori Hirohashi
Original assignee: Yaskawa Information Systems Corporation; Kabushiki Kaisha Yaskawa Denki
Priority date: 2005-06-24
Filing date: 2006-06-22
Publication date: 2006-12-28
Also published as: TW200711373A; JP2008227558A

Abstract

It is possible to provide a network adapter, a communication terminal, a communication path distribution method, and a program capable of building a network by using a short network cable, holding the LAN environment with a terminal at the terminal side even when power of a device constituting the LAN is turned off, and not requiring a complicated work for handling the network cable and checking the connection destination. The network adapter (10) includes a first port (111), a second port (112), a first network controller (121), as second network controller (122), a signal path switching relay (13) and a relay control circuit (14) for controlling operation of the relay (13) according to the state of the communication terminal (20).

Description

Specification

Network adapter, communication terminal, communication route distribution method and program

[0001] The present invention connects a plurality of communication terminals via a LAN (Lodal Area Network) or the like to perform information communication. Therefore, the present invention is connected to two external devices and connected to a communication terminal. The present invention relates to a network adapter, a communication terminal, a communication route distribution method, and a program for performing communication between an external device and a communication terminal.

Background art

[0002] IEEE is a typical example of information communication by connecting multiple communication terminals over a LAN.

There is a LAN standard token ring standardized by the 802.5 committee. Token ring is a ring-type LAN that connects devices that perform communication in a ring, and twisted pair cables are used as LAN cables. The token passing method is used for access control, and the “transmission right” data called a token always circulates around the network, so that the terminal that captures the data transmits the data.

[0003] Also, in systems where data is transmitted and received by connecting communication devices over a limited area such as in factories, offices, and buildings, connections using 10BASE-T and 100BASE-TX are the mainstream. When three or more communication terminals are connected, a cable concentrator called a hub is indispensable as a means of concentrating cables connected to multiple terminal devices and switching them. The

[0004] For example, as a token ring LAN hub used in the token ring LAN shown in FIG. 6, as shown in FIG. 7, a power monitoring circuit 55 for monitoring the power source 51 of the hub and a monitoring result according to this monitoring result. The LAN management circuit bypass relay 53 for bypassing the hub internal transmission lines 56 to 59 from the LAN management circuit 52 to the stations 64a to 66d and the monitoring result to block requests from the stations 64a to 64d to the phantom circuit 61 A circuit provided with a circuit 60 is known. (For example, see JP-A-06-0104036 (page 3, FIG. 1, FIG. 3)). [0005] By applying this conventional technology, when the power supply of a certain terminal 73C malfunctions on the token ring LAN in FIG. 6, the power supply monitoring circuit 55 can output stable power to the hub power supply 51. It is detected that the LAN management circuit bypass relay 53 is switched and the LAN management circuit 52 is in a bypass state.

[0006] Therefore, at the same time as the station is separated from the LAN management circuit 52 in which frame relay cannot be performed normally, the shut-off circuit cuts off the request to the station power phantom circuit. Therefore, even if there is a request for station power or a subscription, the hub will also lose its token ring network power, and the system down caused by unstable power supply can be avoided.

[0007] However, in the conventional technology, when trying to connect a plurality of communication terminals to a LAN, network cables from a plurality of communication terminals are concentrated on a single hub, and are installed in a factory, office, building. However, when communication terminals are scattered, a long network cable may be required for network construction.

[0008] In addition, it is necessary to secure an appropriate space for bundling the cables, and complicated work is required for handling the power network cable and confirming the connection destination.

[0009] Furthermore, the token ring LAN hub of Patent Document 1 must be used with the hub power on in order to maintain the LAN, and the hub 73c power supply in Fig. 6 fails. When the communication path is interrupted, the terminal 74e, 74f on the end side becomes disconnected because the LAN power is also interrupted, which causes a problem.

[0010] Therefore, in the present invention, even when the power of the device for constructing the LAN is turned off, the LAN environment with the terminal on the terminal side is maintained, and the network cable is routed and the connection destination is connected. The purpose of the present invention is to provide a network adapter, a communication terminal, a communication route distribution method, and a program thereof that can construct a network with a short network cable without requiring complicated work such as confirmation.

Disclosure of the invention

In order to solve the above problems, the present invention is configured as follows.

[0012] The present invention 1 is a network for a communication terminal that is connected to two external devices and connected to a communication terminal, and performs communication between the two external devices and the communication terminal. In the adapter, a first port for network connection with the first external device, a second port for network connection with the second external device, a first network controller for communicating with the communication terminal, and the communication terminal A second network controller for communicating with the relay, a relay for switching a signal path between the first port, the second port, the first network controller, and the second network controller, and a state of the communication terminal A relay control circuit for controlling the operation of the relay based on the first network controller, and the relay communicates between the first port and the communication terminal via the first network controller. A first communication state in which the second port communicates with the communication terminal via the first port, and the first port. And the relay control circuit switches the second communication state for direct communication between the communication port and the second port so that the relay control circuit is in the first communication state when the communication terminal is operating normally. The relay is controlled, and at other times, the relay is controlled to be in the second communication state.

[0013] Further, the present invention 2 provides the relay control circuit in which the relay control circuit is set to the first communication state when the power of the communication terminal is on, and to the second communication state otherwise. It is characterized by controlling.

[0014] Further, in the third aspect of the present invention, the relay control circuit is in the first communication state when a normal signal is input as a watchdog timer signal of the communication terminal, and in other cases, the second communication The relay is controlled so as to be in a state.

[0015] Further, in the fourth aspect of the present invention, when the relay control circuit is powered on and the normal signal is input as the watchdog timer signal, the first communication state In other cases, the relay is controlled so as to be in the second communication state.

[0016] Further, the present invention 5 has a structure in which the network adapter for the communication terminal can be detachably attached to the communication terminal, and when the communication terminal power is removed, the second communication state is established. It is characterized by doing.

[0017] Further, the present invention 6 is a communication terminal that is connected to the network adapter for the communication terminal according to the present invention 1 and communicates with two external devices via the network adapter for the communication terminal. A communication path between the network adapter for the communication terminal and the communication terminal When the first network controller force communication signal is received, the data distribution unit analyzes the address that is the destination of the communication signal, and the address is addressed to its own terminal. In some cases, the communication signal is taken into the own terminal. Otherwise, the communication signal is transferred to the second network controller. When the second network controller force also receives the communication signal, the communication signal is transmitted. When the address that is the destination is analyzed and the address is addressed to its own terminal, the communication signal is sent to its own terminal.

If not, transfer the communication signal to the first network controller. If the own terminal also sends a communication signal to the first external device, send the communication signal to the first network controller. When the communication signal is transmitted from the terminal to the second external device, the communication signal is transmitted to the second network controller.

[0018] Further, the present invention 7 includes a watchdog timer that monitors a communication state of the data distribution unit and transmits a normal signal to the network adapter for the communication terminal only when the communication state is normal. Furthermore, it is characterized by providing.

[0019] Also, the present invention 8 is connected to the communication terminal network adapter according to the present invention 1, and communicates with two external devices via the communication terminal network adapter. In the distribution method, when the communication terminal receives the first network controller power communication signal, the address that is the destination of the communication signal is analyzed, and when the address is addressed to the own terminal, the communication signal is Step S1 to be taken into the terminal, Step S2 to transfer the communication signal to the second network controller otherwise, and the address that is the destination of the communication signal when the second network controller also receives the communication signal If the address is addressed to its own terminal, step S3 for capturing the communication signal in its own terminal; Step S4 for transferring the communication signal to the first network controller, and Step S5 for transmitting the communication signal to the first network controller when the terminal power is also transmitted to the first external device. Terminal power When transmitting a communication signal to the second external device, the terminal power is characterized by comprising step S6 of transmitting the communication signal to the second network controller.

[0020] Further, the present invention 9 includes any step from the step S1 to the step S6. A step of determining whether or not the processing is normally completed, a step of causing the watchdog timer to transmit the normal signal if the processing is normally completed, and a data distribution unit if the processing is not successful. Further comprising a step of causing the watchdog timer to transmit the normal signal if normal, and if normal, to causing the watchdog timer to stop transmitting the normal signal if normal. It is characterized by

[0021] Further, the present invention 10 is for a communication terminal that is connected to the network adapter for the communication terminal described in the present invention 1 and communicates with two external devices via the network adapter for the communication terminal. Which is characterized in that it implements the communication path distribution method of the present invention 8.

[0022] Further, the present invention 11 is for a communication terminal that is connected to the network adapter for the communication terminal according to the present invention 3 and communicates with two external devices via the network adapter for the communication terminal. Which is characterized by implementing the communication path distribution method of the ninth aspect of the present invention.

[0023] As described above, according to the first aspect of the present invention, the network adapter power is switched between the first port, the second port, the first network controller, and the second network controller. And a relay control circuit for controlling the operation of the relay based on the relay. The relay communicates between the first port and the communication terminal via the first network controller and the second network controller via the second network controller. The relay control circuit switches between the first communication state in which communication is performed between the two ports and the communication terminal and the second communication state in which direct communication is performed between the first port and the second port. The relay is controlled so as to be in the first communication state, and in other cases, the relay is controlled so as to be in the second communication state. Communication can be held by the second communication state even if it is not normal.

[0024] According to the present invention 2 to the present invention 4, the relay control circuit is set in the first communication state when the power of the communication terminal is on or when a normal signal is input as a watchdog timer signal. , Otherwise the relay is controlled to be in the second communication state, so the communication state using either or both of power off and watchdog timer signal Can be switched.

[0025] According to the fifth aspect of the present invention, the network adapter has a structure that can be detachably attached to the communication terminal. When the communication terminal power is also removed, the network adapter is in the second communication state. Can hold.

[0026] According to the present invention 6 and the present invention 8, when a communication terminal receives a communication signal, when the address that is the destination of the communication signal is addressed to the own terminal, the communication signal is placed in the own terminal. If not, the communication terminal passes the role of the hub because the communication signal is passed, and the communication terminal can connect multiple units without directly connecting the network cable to the hub.

[0027] According to the present invention 7 and the present invention 9, the communication terminal monitors the communication state of the data distribution unit and transmits a watchdog timer that transmits a normal signal to the network adapter only when the communication state is normal. In addition, the LAN environment can be maintained even when the communication status is abnormal.

[0028] In this manner, even when the power of the device for constructing the LAN is turned off, the LAN environment with the terminal on the terminal side is maintained. In addition, a LAN configuration in which multiple network adapters and communication terminals are connected in a daisy chain is possible, and a network can be constructed with a short network cable without the need for complicated operations such as routing the network cable and checking the connection destination.

Brief Description of Drawings

[0029] FIG. 1 is a diagram showing a configuration of a communication terminal and a network adapter for the communication terminal according to the present invention.

FIG. 2 is a diagram for explaining a first communication state and a second communication state.

FIG. 3 is a diagram showing an example of connection between a plurality of network adapters and a communication terminal.

FIG. 4 is a flowchart of the communication path distribution method of the present invention.

FIG. 5 is a flowchart of watchdog timer control.

[FIG. 6] is a diagram showing a configuration of a conventional token ring LAN.

[FIG. 7] is a diagram showing a configuration of a conventional token ring LAN hub.

Explanation of symbols [0030] 10, 10A ~: LOD is the network adapter, 111 is the first port, 112 is the second port, 121 is the first network controller, 122 is the second network controller, 121A and 121B are pulse transformers, 122A and 122B are Ethernet (registered trademark) PHY, 123A, 123B are Ethernet (registered trademark) MAC, 13 ί relay, 131, 132, 133, 134 ί ^ ;, 14 ί relay ff¾ control circuit, 20, 20A-20D are communication terminals , 21 is a watchdog timer, 22 is a power monitoring circuit, 23 is a CPU, 24 is ROM, 25 is RAM, 26 is a CPU bus, 27 is a data distribution unit, 2 8 up to power, 31, 50, 73a to 73fi 301, 302ί external equipment, 303ί LAN cable, 51 power supply, 52 LAN management circuit, 53 LAN management circuit bypass relay, 54 relay drive circuit, 55 power monitoring circuit, 60 shut off Circuit, 61 is a phantom circuit, 62a to 62d are hub internal relays, 63a to 63d are hub internal relays Instead circuit, 64a~64d, 74a~74 1 the station, 65a-65d the station inside the phantom circuit, 71 is a main ring, 7 2A～72c is concentrator.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1

FIG. 1 is a diagram showing a configuration of a communication terminal and a network adapter for the communication terminal according to the present invention. In FIG. 1, the communication terminal 20 performs information communication with the first external device 301 and the second external device 302 via the network adapter 10 connected by the LAN cable 303.

The network adapter 10 communicates with the first port 111 for network connection with the first external device 301, the second port 112 for network connection with the second external device 302, and the communication terminal 20. The first network controller 121, the second network controller 122, the first port 111, the second port 112, the first network controller 121, the relay 13 that switches the LAN signal of the second network controller 122, and the state of the communication terminal 20 And a relay control circuit 14 for controlling the relay 13 based on the above.

[0034] Taking the case of the LAN cable power core as an example, the relay 13 switches the LAN signal at the four contacts 131 to 134 so as to correspond to it. That is, the first port communicates with the communication terminal 20 via the first network controller and passes through the second network controller. Therefore, the first communication state in which the second port communicates with the communication terminal 20 and the second communication state in which direct communication is performed between the first port 111 and the second port 112 are switched.

[0035] The first network controller 121 and the second network controller 122 convert a LAN signal and a signal for a communication terminal such as a bus signal. For example, the pulse transformer 121A, 122A, Ethernet (registered trademark) ) PHY (Physical Layer) 121B, 122B, Ethernet (registered trademark) MAC (Media Access Control) 121C 122C.

The communication terminal 20 includes a power supply 28, a power supply monitoring circuit 22, a watchdog timer 21, and a data distribution unit 27 that distributes communication path data. The data distribution unit 27 includes a CPU 23, a ROM 24, a RAM 25, and a CPU bus 26, which are general configurations of a personal computer, for example. An arithmetic processing unit such as a microcomputer may be used instead of the CPU 23.

FIG. 2 is a diagram for explaining the first communication state and the second communication state.

[0038] In the first communication state, as shown in FIG. 2 (a), the second port 112 and the second network controller 122 are connected via the contact 131, and the first port 111 and the first network controller 121 are connected.

On the other hand, in the second communication state, the first port 111 and the second port 112 are connected via the contact 131 as shown in FIG. The same applies to the force contacts 132 to 134, which are shown only for the contact 131 in the figure.

The relay 13 is controlled by the relay control circuit 14. The relay control circuit 14 controls the relay 13 so as to be in the first communication state only when the communication terminal 20 is operating normally, and so as to be in the second communication state at other times. Control relay 13.

[0041] For example, the relay 13 is controlled via the relay control circuit 14 with the signal of the power monitoring circuit 22 that monitors the power supply abnormality of the communication terminal 20 and the watchdog timer 21 that detects the abnormal operation of the communication terminal 20. When the communication terminal 20 is turned on and the watchdog timer 21 signal is input as a normal signal, the first communication state is set. Otherwise, the second communication is set. What is necessary is just to comprise so that it may be set as a state. As a result, the watchdog timer 21 periodically monitors the communication status and the power supply monitoring circuit 22 supplies power. Since it senses off instantly, it switches to the second communication state as soon as the communication terminal is not operating normally or power is cut off. For this reason, a stable LAN environment is maintained.

In addition to this, the power not shown in the figure may be omitted, and the relay 13 may be controlled based only on the power supply of the communication terminal 20 without providing the watchdog timer 21. In this case, even if the communication terminal does not have a watchdog timer structure, if the relay control circuit 14 has the function of the power monitoring circuit 22, the software can be changed without changing the hardware configuration of the communication terminal 20. Only the object of the present invention can be achieved.

Although not shown, the relay 13 may be controlled based on only the signal of the watchdog timer 21 without providing the power supply monitoring circuit 22. In this case, the structure of the network adapter 10 and the communication terminal 20 can be simplified.

[0044] With the configuration described above, only when the communication terminal 20 is operating normally, information communication between the first external device 301 and the communication terminal 20, and information between the second external device 302 and the communication terminal 20 are performed. When the communication terminal 20 is not operating normally or is turned off, information communication between the first external device 301 and the second component device 302 is performed directly, and the LAN environment is Retained.

[0045] Further, the network adapter 10 and the communication terminal 20 can be connected to each other via a LAN.

FIG. 3 is a diagram illustrating a connection example of a plurality of network adapters and communication terminals. Here, 1 OA to 10D are network adapters, 20A to 20D are communication terminals, and the network adapters 10A to 10D are connected by a LAN cable 303. One end of the network adapter 10A is connected to the hub 31. By connecting in this way, it is possible to construct a network with the short network cable 303 without requiring complicated work such as handling the network cable 303 and confirming the connection destination.

When the communication terminal 20A is not operating normally, the network adapter 10A is in the second communication state, and the hub 31 and the communication terminal 20B are substantially directly connected via the LAN. In other words, when building a network by connecting communication terminals, the network adapter and communication terminal act as the hub, and the communication terminal connects the network cable directly to the hub. It is possible to connect a plurality of units without continuing.

[0048] The network adapter 10 is preferably configured to be detachable from the communication terminal 20, such as a card-type adapter. When the network adapter 10 is removed from the communication terminal 20, the second communication state can be maintained because the communication terminal 20 is not operating normally.

[0049] For example, in FIG. 3, even if the network adapter 10C is disconnected from the communication terminal 20C, if the LAN cable 303 is left connected to the network adapter 10C, the LAN environment can be maintained. It is possible to carry around only 20C with LAN power removed temporarily.

[0050] The network adapter 10 may have a USB interface so that it can be connected to the communication terminal 20 via a USB (Universal Serial Bus)! /.

[0051] It is more preferable that the relay control circuit 14, the first network controller 121, and the second network controller 122 are supplied with power 28 from the communication terminal 20.

Next, communication path distribution processing for distributing communication signal paths at the communication terminal 20 will be described.

[0053] When the data distribution unit 27 receives a communication signal from the first network controller 121, the data distribution unit 27 analyzes the address that is the communication destination, and when the address is addressed to its own terminal, the data distribution unit 27 If it is not received, the communication signal is transferred to the second network controller 122.

[0054] When a communication signal is received from the second network controller 122, the address as the communication destination is analyzed. When the address is addressed to the own terminal, the communication signal is taken into the communication terminal 20; Otherwise, the communication signal is transferred to the first network controller 121.

When a communication signal is transmitted from the communication terminal 20 to the first external device 301, the communication signal is transmitted to the first network controller 121.

When a communication signal is transmitted from the communication terminal 20 to the second external device 122, the communication signal is transmitted to the second network controller 122.

[0057] As described above, the communication path distribution process is performed by the first network controller 121, the second network controller. The controller 122 and the communication terminal 20 have a function of switching communication paths, and this function is realized by software processing, for example.

That is, data input from the first port 111 and the second port 112 is converted into a signal by the first or second network controller 121, 122, and via the CPU bus 26 of the communication terminal 20, the ROM 24 Or it is processed by the program of the data distribution part 27 stored in RAM25.

[0059] When the information is transmitted from the communication terminal 20 to the first or second external device 301, 302, it is similarly processed by the program.

FIG. 4 shows a flowchart of the communication path distribution method of the present invention. This method is implemented by the program of the data distribution unit 27 of the communication terminal 20.

[0061] When a LAN signal is input from the first port 111 in step S101, the first network controller 121 performs signal conversion into a communication signal for a communication terminal such as a LAN signal power bus signal in step S102. In step S 103, the communication terminal 20 receives a communication signal from the first network controller 121. In step S104, the data distribution unit 27 analyzes the address that is the destination of the communication signal. If the address is addressed to the own terminal, the communication signal is taken into the own terminal in step S105. On the other hand, when the address is not addressed to the own terminal, the process proceeds to step S201, and the communication signal is transferred to the second network controller 122. In step S202, the second network controller 122 performs signal conversion from the communication signal for the communication terminal 20 to the LAN signal. In step S203, the LAN signal is output from the second port 112.

[0062] Here, if the communication terminal 20 receives a communication signal via the first network controller 121 and the communication signal is destined for the own terminal, the step of capturing the signal is set to S1, and is not destined for the own terminal. In this case, the step of transferring to the second network controller 122 is S2. That is, S103, S104 and S105 constitute step S1, and S103, S104 * 5 and S201 constitute step S2.

[0063] When a LAN signal is input from the second port 112 in step S301, the second network controller 122 performs signal conversion into a communication signal for a communication terminal such as a LAN signal bus signal in step S302. In step S303, the communication terminal 20 becomes the second network controller. A communication signal is received from 122. In step S304, the data distribution unit 27 analyzes the address that is the destination of the communication signal. If the address is addressed to the own terminal, the communication signal is taken into the communication terminal 20 in step S305. On the other hand, when the address is not addressed to the own terminal, the process proceeds to step S401, and the communication signal is transferred to the first network controller 121. In step S402, the first network controller 121 performs signal conversion from a communication signal for the communication terminal 20 to a LAN signal. In step S403, the RAN signal is output from the first port 111.

[0064] Here, if the communication terminal 20 receives a communication signal via the second network controller 122 and the signal is destined for the own terminal, the step of capturing the communication signal is set as S3, and is not destined for the own terminal. In this case, the step of transferring to the first network controller 121 is S4. That is, S303, S304, and S305 constitute step S3, and S303, S304, and S401 constitute step S4.

[0065] When the own terminal power is also going to send a LAN signal to the first external device 301, the communication terminal 20 generates a communication signal in step S501. In step S502, the data distribution unit 27 adds an address to the communication signal and transfers it to the first network controller 121. In step S503, the first network controller 121 converts the communication signal power for the communication terminal 20 into a RAN signal. In step S504, a LAN signal is output from the first port 111.

[0066] When the own terminal power is also going to send a LAN signal to the second external device 302, the communication terminal 20 generates a communication signal in step S601. In step S602, the data distribution unit 27 adds an address to the communication signal and transfers it to the second network controller 122. In step S603, the second network controller 122 converts the communication signal power for the communication terminal 20 into a RAN signal. In step S604, a LAN signal is output from the second port 112.

Here, communication terminal 20 generates a communication signal, adds an address to the communication signal, and transfers this to first network controller 121. Steps S501 and S502 are set as step S5, and are transferred to second network controller 122. Steps S601 and S602 are set as Step S6.

[0068] By the communication path distribution method according to the above steps S1 to S6, the communication terminal 20 Signal distribution in is realized.

[0069] Note that when the communication terminal 20 is not sure whether to send a LAN signal to the first external device 301 or the second external device 302, both steps S5 and S6 are performed on the LAN signal. Do it!

Next, the function of the watchdog timer 21 will be described. If the communication terminal 20 does not operate normally, communication between the first external device 301 and the second external device 302 cannot be performed, and the LAN environment is not maintained by blocking the communication path. In order to avoid this, the watchdog timer 21 periodically monitors the operation of the communication terminal 20 by confirming that a predetermined normal signal is sent from the CPU 23.

[0071] When the network adapter 10 monitors both the power monitoring circuit 22 and the watchdog timer 21, the network adapter 10 is turned on until the power monitoring circuit 22 of the communication terminal 20 outputs normally. In the second communication state, when the power monitoring circuit 22 outputs a normal signal after the power is turned on, and the program stored in the ROM 24 or RAM 25 is activated and the communication terminal 20 becomes communicable. The watchdog timer 21 outputs a normal signal, and the relay control circuit 14 controls the relay 13 that makes the transition to the first communication state.

Thereafter, the power monitoring circuit 22 outputs a normal signal to the relay control circuit 14 only when the power supply voltage is normal. When an abnormality in the power supply voltage is detected, an abnormality signal is output to the relay control circuit 14, and the relay control circuit 14 switches the relay 13 to the second communication state.

[0073] In addition, the watchdog timer 21 outputs a normal signal to the relay control circuit 14 if a normal access is received from the CPU 23 within a certain hour. If normal access is not received from the CPU 23 within a certain hour, an abnormal signal is output to the relay control circuit 14, and the relay control unit 14 switches the relay 13 to the second communication state.

Here, the control of the watchdog timer 21 is processed by a program stored in the data distribution unit 27 as part of the communication path distribution method.

FIG. 5 is a flowchart of watchdog timer control.

[0076] In step S11, it is determined whether or not any of the steps from step S1 to step S6 in Fig. 4 has successfully completed the process, and if successful, the process proceeds to step S13. Send a normal signal to the hot dog timer 21. If not successful, proceed to step S12 and check the status of the data distributor 27. If the data distribution unit 27 is normal, the process proceeds to step S13. If it is not normal, go to step S14 and stop the watchdog timer 21 from sending a normal signal.

[0077] In addition, the watchdog timer is not controlled by the program in this way, and the watchdog timer transmits an abnormal signal when the access to the watchdog timer is performed within a certain period from the CPU and the access is stopped. It is also possible to perform control.

Thus, according to the present invention, the LAN environment with the terminal on the terminal side is maintained even when the power of the device for constructing the LAN is turned off. In addition, a LAN configuration that connects multiple network adapters and communication terminals in a daisy chain is possible, making it possible to construct a network with short network cables without the need for complicated work such as checking the network cable connection destination. It is.

Industrial applicability

[0079] As a communication terminal in which the present invention is used, it can be used in a factory-connected FA device or a personal computer connected in a LAN in a workplace or school, and the network adapter of the present invention is used. By using it, the effects and effects described in the embodiments are exhibited.

Claims

The scope of the claims

[1] In a network adapter for a communication terminal that is connected to two external devices and connected to a communication terminal and communicates between the two external devices and the communication terminal.

A first port for network connection with a first external device;

A second port for network connection with a second external device;

A first network controller for communicating with the communication terminal;

A second network controller for communicating with the communication terminal;

A relay for switching a signal path between the first port, the second port, the first network controller, and the second network controller;

A relay control circuit for controlling the operation of the relay based on the state of the communication terminal,

The relay communicates between the first port and the communication terminal via the first network controller, and communicates between the second port and the communication terminal via the second network controller. A first communication state to perform;

Switching between a first communication state and a second communication state in which direct communication is performed between the first port and the second port, so that the relay control circuit enters the first communication state when the communication terminal is operating normally. A network adapter for a communication terminal, wherein the relay is controlled so that the relay is in a second communication state at other times.

[2] The relay control circuit controls the relay so as to be in a first communication state when the power of the communication terminal is on and in a second communication state otherwise. The network adapter for a communication terminal according to claim 1.

[3] The relay control circuit sets the first communication state when a normal signal is input as a watchdog timer signal of the communication terminal, and sets the second communication state otherwise. The network adapter for a communication terminal according to claim 1, wherein the relay is controlled.

[4] The relay control circuit enters the first communication state when the communication terminal is powered on and a normal signal is input as the watchdog timer signal. 2. The network adapter for a communication terminal according to claim 1, wherein the relay is controlled to be in a second communication state when outside.

5. The network adapter for the communication terminal has a structure that can be detachably attached to the communication terminal, and when the communication terminal force is removed, the network adapter is in a second communication state. A network adapter for communication terminals as described in 1.

[6] In a communication terminal that is connected to the network adapter for the communication terminal according to claim 1 and communicates with two external devices via the network adapter for the communication terminal, the network adapter for the communication terminal and A data distribution unit for distributing communication paths between the communication terminals;

When receiving the first network controller power communication signal, the data distribution unit analyzes an address that is a destination of the communication signal. When the address is addressed to the own terminal, the data distribution unit sends the communication signal to the own terminal. Otherwise, transfer the communication signal to the second network controller, and when the second network controller also receives the communication signal, analyze the address that is the destination of the communication signal and find the address If it is addressed to the local terminal, the communication signal is taken into the local terminal. Otherwise, the communication signal is transferred to the first network controller, and the communication signal is transmitted from the local terminal to the first external device. In this case, the communication signal is transmitted to the first network controller, and the terminal power is also transmitted to the second external device.

When transmitting a communication terminal, the communication signal is transmitted to the second network controller.

[7] The method further comprises a watchdog timer that monitors a communication state of the data distribution unit and transmits a normal signal to the network adapter for the communication terminal only when the communication state is normal. Item 6. The communication terminal according to item 6.

[8] In a communication path distribution method for a communication terminal that is connected to the network adapter for the communication terminal according to claim 1 and communicates with two external devices via the network adapter for the communication terminal.

When the communication terminal receives the first network controller power communication signal, it analyzes the address that is the destination of the communication signal, and when the address is addressed to its own terminal, Step SI to capture the communication signal in its own terminal,

If not, the step S2 of transferring the communication signal to the second network controller;

When the second network controller also receives a communication signal, it analyzes the address that is the destination of the communication signal, and when the address is addressed to its own terminal, takes the communication signal into its own terminal. ,

If not, step S4 for transferring the communication signal to the first network controller;

When transmitting a communication signal to the first external device, step S5 for transmitting the communication signal to the first network controller;

Self-terminal capability A communication path distribution method comprising: step S6 of transmitting the communication signal to the second network controller when transmitting a communication signal to the second external device.

[9] From step S1 to step S6! /, A step of determining whether the deviation step has successfully completed the process;

A step of causing the watchdog timer to send the normal signal when the operation is normally completed; and

If it does not end normally, the status of the data distribution unit is checked. If it is normal, the normal signal is sent to the watchdog timer. If not normal, the normal signal is sent to the watchdog timer. The communication path distribution method according to claim 8, further comprising the step of stopping transmission.

[10] A program for a communication terminal that is connected to the network adapter for the communication terminal according to claim 1 and communicates with two external devices via the network adapter for the communication terminal,

A communication terminal program for carrying out the communication path distribution method according to claim 8.

[11] A program for a communication terminal that is connected to the network adapter for the communication terminal according to claim 3 and communicates with two external devices via the network adapter for the communication terminal Because

A program for a communication terminal, which implements the communication route distribution method according to claim 9.