JP2004193865A - Network connection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a network connection apparatus capable of restoring a circuit unit whose operation is stopped. <P>SOLUTION: The network connection apparatus is configured to include: a protocol controller 102 for performing transmission control of data; a watchdog timer 103 for outputting a reset signal to a predetermined circuit unit when counting a predetermined time; a comparison circuit 105 for comparing a message transmitted/received by the protocol controller 102 with a mobile station stored in a storage circuit 104; and a CPU 106 for controlling the operation of the protocol controller 102 to thereby restore the circuit unit whose operation is stopped. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a network connection device, and more particularly, to a network connection device that recovers, using a reset signal, a device on a network that has stopped operating due to a runaway CPU, for example.
[0002]
[Prior art]
Conventionally, this type of network connection device has a signal transmission / reception unit provided with a CPU that operates asynchronously with a CPU that is a control center of a device connected to a network. By receiving a unique signal indicating the operation state and sending a reset signal to a device whose operation has been stopped due to runaway of the CPU, for example, the device is returned to the initial state and restored to the normal operation state. (For example, see Patent Document 1).
[Patent Document 1]
JP-A-2001-212232 (page 6, FIG. 2)
[0003]
[Problems to be solved by the invention]
However, in such a conventional network connection device, since the operation state of the device is grasped by a unique signal, it is necessary to define a signal for each operation state, and a general-purpose communication protocol cannot be used. There was a problem.
[0004]
Further, in the conventional network connection device, when the signal transmission / reception unit becomes inoperable for some reason, a unique signal indicating the operation state cannot be transmitted / received, so that the operation state of the device on the network cannot be known. was there.
[0005]
Furthermore, in the conventional network connection device, even after the device that has stopped operating receives the reset signal, if the signal transmitting / receiving unit is inoperable, a unique signal indicating the operating state cannot be transmitted / received. However, there is a problem that it is not possible to know the operation status of the devices on the network.
[0006]
The present invention has been made to solve such a problem, and a general-purpose communication protocol can be used. Even when a signal transmission / reception unit, a CPU, and the like become inoperable, a signal is restored by a reset signal. Further, the present invention provides a network connection device capable of transmitting operating state information to a network even when a signal transmitting / receiving unit, a CPU, and the like become inoperable after receiving a reset signal. .
[0007]
[Means for Solving the Problems]
The network connection device of the present invention transmits and receives a message conforming to a predetermined communication protocol to and from a network, and outputs a reset signal when a predetermined time is counted, and a protocol control unit that performs data transmission control. Reset signal output means, and a clock control means for stopping the timing of the time when the message transmitted / received by the protocol control means matches a previously stored message. ing.
[0008]
With this configuration, when a message transmitted / received by the protocol control unit that performs data transmission control based on a predetermined communication protocol matches a message stored in advance, that is, when the device is operating normally. Since the reset signal output means does not output the reset signal, the transmission and reception of data with the network can be continued. On the other hand, when the device is not operating normally, the reset signal output means outputs a reset signal, so that a normal operation state can be set by the reset signal.
[0009]
Further, the network connection device of the present invention, when the message transmitted by the protocol control means is a message that rejects either the transmission of the data or the reception of the data, the timing control means, the time control It has a configuration characterized by continuing timekeeping.
[0010]
With this configuration, for example, when the free space of the reception buffer of the protocol control unit is insufficient, the protocol control unit transmits a message rejecting the reception of data, and the time control unit sets the time by the reset signal output unit. Since the clocking is continued, the reset signal output means can output a reset signal when the predetermined time has been measured, and can set the circuit unit which is not operated by the reset signal to an initial state.
[0011]
Further, the network connection device of the present invention is a protocol control means for transmitting / receiving a message conforming to a predetermined communication protocol to / from a network and controlling data transmission, and wherein the protocol control means transmits the data and transmits the data. And a reset signal output means for outputting a reset signal when a message rejecting any of the above is transmitted to the network.
[0012]
With this configuration, for example, when the free space of the reception buffer of the protocol control unit is insufficient, the protocol control unit transmits a message rejecting data reception, and the reset signal output unit outputs a reset signal. In addition, a circuit unit that is not operating can be immediately brought into an initial state by a reset signal.
[0013]
In addition, the network connection device of the present invention is an operation device that stores operation state information indicating which of an operation state in which a circuit unit in a predetermined range is operating and a stopped state in which operation is stopped. It has a configuration characterized by comprising state information storage means.
[0014]
With this configuration, the operating state information storage unit stores the operating state and the stopped state of the circuit unit in a predetermined range, so that the circuit unit in the stopped state can be known, and the circuit unit in the stopped state is reset. The initial state can be set by a signal.
[0015]
Further, the network connection device of the present invention has a configuration characterized by comprising operating state information transmitting means for transmitting the operating state information to the network.
[0016]
With this configuration, the operating state information transmitting unit transmits the operating state information to the network, so that the operating state information can be notified to other nodes on the network.
[0017]
Further, the network connection device of the present invention has a configuration characterized in that the protocol control means includes message response means for responding to the message from the network when transmission / reception of the message is stopped. are doing.
[0018]
With this configuration, the message response unit can transmit and receive a message instead of the protocol control unit when the protocol control unit stops transmitting and receiving the message.
[0019]
The reset method of the network connection device of the present invention, when a predetermined time is measured, a reset signal output step of outputting a reset signal, and when a message transmitted and received on the network matches a previously stored message, And a timing stop step of stopping the timing of the time.
[0020]
According to this method, when the message transmitted / received to / from the network does not match the message stored in advance, that is, when the apparatus is not operating normally, a reset signal is output in the reset signal output step.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
(First Embodiment)
First, the configuration of the network connection device according to the first embodiment of the present invention will be described.
[0023]
As shown in FIG. 1, a network connection device 100 according to the present embodiment transmits and receives a message conforming to a predetermined communication protocol to and from a transceiver 101 that exchanges data with the network, and controls data transmission. A protocol controller 102, a watchdog timer (hereinafter, referred to as WDT) 103 for outputting a reset signal to a predetermined circuit unit when a predetermined time is counted, and transmission and reception by the protocol controller 102. A storage circuit 104 that stores in advance a message to be transmitted, a comparison circuit 105 that compares a message transmitted and received by the protocol controller 102 with a message stored in the storage circuit 104, and controls the operation of the protocol controller 102. And a CPU106 to.
[0024]
In FIG. 1, the above-described predetermined circuit unit refers to the protocol controller 102, the comparison circuit 105, and the CPU 106 which are set so that the reset signal e output from the WDT 103 can be input.
[0025]
The transceiver 101 transmits / receives transmission / reception data a transmitted / received to / from the network by the protocol controller 102 to / from the network. The protocol controller 102 transmits / receives a message conforming to a predetermined communication protocol to / from a network, controls data transmission, and outputs a transmission enable signal b to the transceiver and the comparison circuit 105.
[0026]
The WDT 103 includes a timer for measuring a predetermined time. When the predetermined time is measured by the timer, the WDT 103 outputs a reset signal e to the protocol controller 102, the comparison circuit 105, and the CPU 106 to initialize the state. It has become. The storage circuit 104 stores in advance a bit pattern of a message to which the protocol controller 102 responds to a message from the network (hereinafter, simply referred to as a response pattern).
[0027]
The comparison circuit 105 compares the transmission / reception data a transmitted / received from the protocol controller 102 with the response pattern c read from the storage circuit 104, and when the transmission / reception data a matches the response pattern c, the timer of the WDT 103 counts. Is output to the WDT 103. The CPU 106 controls the protocol controller 102 via the bus f.
[0028]
Note that the protocol controller 102, the WDT 103, and the comparison circuit 105 constitute a protocol control unit, a reset signal output unit, and a timing control unit, respectively.
[0029]
Next, the operation of the network connection device 100 according to the present embodiment will be described with reference to FIGS. Here, a communication protocol ARCNET (Attached Resource Computer Network) based on 878.1 of ANSI (American National Standards Institute) will be described as an example. Further, as shown in FIG. 2, in a logical ring 201 in which three devices (hereinafter, referred to as nodes) are connected to a network, a message is transmitted counterclockwise through the logical ring 201.
[0030]
It is assumed that the storage circuit 104 stores a response pattern based on the communication protocol ARCNET. Specifically, a token indicating a transmission right, a free buffer inquiry for inquiring whether or not there is free space in a buffer on the other end, a packet transmitted / received via a network, an ACK for accepting a request from a device connected to the network (Acknowledgement) and the extension of a NAK (Negative Acknowledgement) message that rejects either data transmission or data reception in response to a request from a device connected to the network.
[0031]
FIG. 3 shows a procedure in which messages are exchanged between nodes # 1 to # 3 on the logical ring 201 shown in FIG. The procedure is illustrated.
[0032]
Initially, procedure A shows that no node intends to transmit a packet, and that a token indicating the transmission right is being exchanged between the nodes.
[0033]
Next, the procedure B shows a case where the packet transmission from the node # 1 to the node # 2 is successful. First, before transmitting a packet to the node # 2, the node # 1 inquires of the node # 2 whether or not there is free space in the buffer of the node # 2 by a free buffer inquiry message. Since an ACK is returned from the node # 2 to the message of the free buffer inquiry, the node # 1 knows that there is free space in the buffer of the node # 2, and transmits the packet to the node # 2. Then, the node # 2 returns an ACK indicating that the packet transmission has been normally completed to the node # 1, thereby indicating that the packet transmission from the node # 1 to the node # 2 is successful.
[0034]
Next, the procedure C shows a case where transmission from the node # 2 to the node # 3 fails. First, before transmitting the packet to the node # 3, the node # 2 inquires of the node # 3 whether or not there is free space in the buffer of the node # 3 by a free buffer inquiry message. In response to the free buffer inquiry message, the node # 3 transmits to the node # 2 a message NAK rejecting reception of a packet because there is no free space in the buffer. Furthermore, as a result of repeating the transmission of the free buffer inquiry message, the node # 2 gives up the packet transmission because the response of the message NAK is continuous, and sends the token to the node # 3. In addition to the procedure 3, for example, a message may not be transmitted correctly due to a transmission error, and the receiving node may not respond and transmission may fail.
[0035]
Next, the operation of the network connection device 100 according to the present embodiment will be described with reference to the flowcharts of FIGS.
[0036]
4, first, the transmitted / received data a transmitted / received is output to the transceiver 101 and the comparison circuit 105 by the protocol controller 102 (step S401). Next, the protocol controller 102 outputs the transmission enable signal b to the transceiver 101 and the comparison circuit 105 (step S402). Next, the response pattern c stored in advance is read from the storage circuit 104 by the comparison circuit 105 (step S403).
[0037]
Subsequently, the comparison circuit 105 compares the transmission / reception data a input from the protocol controller 102 with the response pattern c stored in the storage circuit 104 in advance (step S404). In step S404, when the transmission / reception data a matches the response pattern c, the comparison circuit 105 compares the transmission / reception data a with the message NAK (step S405).
[0038]
When the transmission / reception data a does not match the message NAK in step S405, the comparator 105 outputs a timer release signal d for releasing the timer of the WDT 103 described later to the WDT 103 (step S406).
[0039]
On the other hand, if the transmission / reception data a does not match the response pattern c in step S404, the process returns to step S401. As an example of a case where the transmission / reception data a does not match the response pattern c, there is a case where the protocol controller 102, the CPU 106, and the like cannot continue normal operations for some reason and the operation is stopped. In this case, since the process returns to step S401, the timer release signal d is not output to the WDT 103, and when a predetermined time is measured by the timer of the WDT 103, the circuit unit connected to the WDT 103 is returned to the initial state. It becomes.
[0040]
Also, if the transmission / reception data a matches the message NAK in step S405, the process returns to step S401. As an example of the case where the transmission / reception data a matches the message NAK in step S405, there is a case where the runaway of the CPU 106 makes it impossible to read the reception buffer of the protocol controller 102. In this case, since the process returns to step S401, the timer release signal d is not output to the WDT 103, and when a predetermined time is measured by the timer of the WDT 103, the circuit unit connected to the WDT 103 is returned to the initial state. It becomes.
[0041]
Next, the operation of the WDT 103 will be described with reference to the flowchart of FIG.
[0042]
In FIG. 5, first, a timer provided in the WDT 103 starts measuring time (step S501). For example, WDT 103 can be configured so that a timer starts timing when a token is transmitted to the next node. Next, it is determined whether or not the timer release signal d has been received from the comparison circuit 105 (step S502). The timer release signal d is a signal for stopping the time measurement started by the timer in step S501 and restarting the time measurement.
[0043]
If it is not determined in step S502 that the timer release signal d has been received from the comparison circuit 105, it is determined whether the time measured by the timer has exceeded a predetermined time (step S503). Here, the predetermined time is, for example, a time during which a message addressed to the own node is not received as in node # 3 in procedure B and node # 1 in procedure C shown in FIG. The time exceeding the maximum value.
[0044]
On the other hand, if it is determined in step S502 that the timer release signal d has been received from the comparison circuit 105, the timer is reset (step S504), and the process returns to step S501.
[0045]
If it is determined in step S503 that the time measured by the timer has exceeded the preset time, a reset signal e is output to the protocol controller 102, the comparison circuit 105, and the CPU 106 (step S505). , Comparison circuit 105 and CPU 106 are initialized.
[0046]
In step S503, when it is determined that the time measured by the timer has exceeded the preset time, the reset signal e is set to be low regardless of the step in the flowchart shown in FIG. It is output to the circuit described above.
[0047]
In addition, when the transmission / reception data a matches the message NAK in step S405, the WDT 103 may output the reset signal e before the predetermined time is measured.
[0048]
Step S505 described above constitutes a reset signal output step, and steps S406, S502, and S504 constitute a timing stop step.
[0049]
As described above, according to the network connection device 100 of the present embodiment, by comparing the transmission / reception data transmitted / received by the protocol controller 102 with the response pattern stored in the storage circuit 104 in advance, the circuit unit in the device is , And a reset signal is output to a circuit unit that is not operating, so that a general-purpose communication protocol can be used, and even if the protocol controller 102 and the CPU 106 become inoperable, The normal operation state can be restored by the reset signal.
[0050]
(Second embodiment)
First, the configuration of the network connection device according to the second embodiment of the present invention will be described.
[0051]
Note that, of the configuration of the network connection device 600 of the present embodiment, the same configuration as the configuration of the network connection device 100 of the first embodiment is the same as the configuration of the network connection device 100 of the first embodiment. The same reference numerals are given and the detailed description is omitted.
[0052]
As shown in FIG. 6, the configuration of the network connection device 600 according to the present embodiment is the same as the configuration in which the status storage circuit 601 and the decode circuit 602 are provided in the network connection device 100 according to the first embodiment.
[0053]
The status storage circuit 601 has operating state information (hereinafter, referred to as status information) indicating which of an operating state in which circuit units in a predetermined range are operating and a stopped state in which operation is stopped. Is to be remembered. This status information is obtained via the bus f, and the status storage circuit 601 stores the latest status information. Note that the status storage circuit 601 constitutes an operating state information storage unit.
[0054]
The decode circuit 602 decodes the status information g output from the status storage circuit 601 and the reset signal e output from the WDT 103, and outputs the reset signal individually to a predetermined range of circuit units. I have.
Note that the signals individually output by the decode circuit 602 are hereinafter referred to as individual reset signals h. In FIG. 6, the circuit units in a predetermined range refer to the protocol controller 102, the comparison circuit 105, the CPU 106, and other circuits (not shown) in the apparatus connected to the decoding circuit 602, and reset. The target circuit unit.
[0055]
Next, the operation of the network connection device 600 according to the present embodiment will be described. Note that among the operations of the network connection device 600 according to the present embodiment, detailed descriptions of operations that are the same as the operations of the network connection device 100 according to the first embodiment are omitted.
[0056]
In FIG. 6, when the timer of the WDT 103 has counted a preset time, the reset signal e is output to the decode circuit 602 by the WDT 103. Next, the status information g output from the status storage circuit 601 and the reset signal e output from the WDT 103 are decoded by the decoding circuit 602. Then, the individual reset signal h is output from the decode circuit 602 based on the status information g, and the circuit units in the stopped state are set to the initial state.
[0057]
Here, the operation of the decoding circuit 602 will be described with reference to Table 1.
[0058]
Table 1 shows the truth values of the decode circuit when the circuit units in the predetermined range are the protocol controller 102, the comparison circuit 105, and the CPU 106. In Table 1, a circle indicates a case where the individual reset signal h is output, and a cross indicates a case where the individual reset signal h is not output.
[0059]
For example, when the status information output from the status storage circuit 601 is information on a momentary power interruption, when the WDT 103 outputs the reset signal e, the decode circuit 602 individually transmits to the protocol controller 102, the comparison circuit 105, and the CPU 106. The reset signal h is output. On the other hand, when the status information output from the status storage circuit 601 is stack overflow information and the WDT 103 outputs the reset signal e, the decode circuit 602 outputs the individual reset signal h only to the CPU 106.
[0060]
In Table 1, Don't Care indicates an operating state in which the protocol controller 102, the comparison circuit 105, and the CPU 106 are operating. On the other hand, the instantaneous power interruption, the stack overflow, the reception buffer overflow, and the transmission timeout are indicated by the protocol. A stop state in which the controller 102, the comparison circuit 105, and the CPU 106 stop operating is shown.
[0061]
As described above, according to the network connection device 600 of the present embodiment, the status storage circuit 601 stores the status information of the circuit unit, and the decode circuit 602 sends a reset signal to the circuit unit individually based on the status information. , The circuit unit can be selectively restored by the reset signal.
[0062]
(Third embodiment)
First, the configuration of the network connection device according to the third embodiment of the present invention will be described.
[0063]
Note that, of the configuration of the network connection device 700 of the present embodiment, the configuration that is the same as the configuration of the network connection device 600 of the second embodiment is the same as the configuration of the network connection device 600 of the second embodiment. The same reference numerals are given and the detailed description is omitted.
[0064]
As shown in FIG. 7, the configuration of the network connection device 700 according to the present embodiment includes a status storage circuit 701 instead of the status storage circuit 601 provided in the network connection device 600 according to the second embodiment. , Switch 703, and monostable multivibrator (hereinafter simply referred to as MM) 702.
[0065]
The status storage circuit 701 stores status information of circuit units in a predetermined range, and transmits the status information to the network as a broadcast packet. Note that the status storage circuit 701 constitutes an operating state information transmitting unit.
[0066]
The switch 703 switches the connection between the transceiver 101 and any one of the status storage circuit 701 and the protocol controller 102. When the reset signal e is input from the WDT 103, the MM 702 outputs a switching signal j that causes the switch 703 to perform a switching operation.
[0067]
The switch 703 connects the protocol controller 102 and the transceiver 101 until the switching signal j is input from the MM 702, and the transmission / reception data a transmitted and received by the protocol controller 102 is selected. On the other hand, when the switching signal j is input from the MM 702 for a certain time, the switch 703 connects the status storage circuit 701 to the transceiver 101 for a certain time, and transmits / receives data from / to the status storage circuit 701 (hereinafter referred to as spare transmission / reception data). ) I is selected for a certain period of time.
[0068]
Next, the operation of the network connection device 700 according to the present embodiment will be described. Note that, among the operations of the network connection device 700 of the present embodiment, detailed descriptions of the same operations as those of the network connection device 600 of the second embodiment are omitted.
[0069]
In FIG. 7, when the timer of the WDT 103 measures a preset time, the reset signal e is output to the decode circuit 602 by the WDT 103. Next, the decoding circuit 602 decodes the status information g output from the status storage circuit 601 and the reset signal e output from the WDT 103.
Then, based on the status information g, the individual reset signal h is output from the decode circuit 602 to the circuit unit in the stopped state. The circuit unit in the stopped state is initialized.
[0070]
On the other hand, the reset signal e output from the WDT 103 is input to the MM 702, and the switching signal j is output to the switch 703 by the MM 702. Subsequently, the status storage circuit 701 and the transceiver 101 are connected by the switch 703. When the status storage circuit 701 receives the token, the status information stored in the status storage circuit 701 is transmitted to the network as a broadcast packet.
[0071]
As described above, according to the network connection device 700 of the present embodiment, the status storage circuit 701 stores the status information of the circuit unit, and transmits the status information to the network after the circuit unit is reset. Therefore, even when the protocol controller 102 is not restored by the reset signal, the status information can be transmitted to another node connected to the network.
[0072]
(Fourth embodiment)
First, the configuration of the network connection device according to the fourth embodiment of the present invention will be described.
[0073]
Note that, of the configuration of the network connection device 800 of the present embodiment, the configuration that is the same as the configuration of the network connection device 700 of the third embodiment is the same as the configuration of the network connection device 700 of the third embodiment. The same reference numerals are given and the detailed description is omitted.
[0074]
As shown in FIG. 8, the configuration of the network connection device 800 of the present embodiment is different from the configuration of the network connection device 700 of the third embodiment in that the decoding circuit 602 provided in the network connection device 700 is removed and an automatic response is performed instead of the status storage circuit 701. This is the same as the configuration including the circuit 801.
[0075]
The automatic response circuit 801 responds to a message from the network when the protocol controller 102 stops transmitting and receiving a message, for example, when the protocol controller 102 is hung up. For example, when a token addressed to the own node is received, a token addressed to the next node is automatically transmitted, and when a free buffer inquiry message addressed to the own node is received, a NAK is automatically returned. I have. Note that the automatic response circuit 801 constitutes a message response unit.
[0076]
Next, the operation of the network connection device 800 according to the present embodiment will be described. Note that, among the operations of the network connection device 800 of the present embodiment, detailed descriptions of the same operations as those of the network connection device 700 of the third embodiment are omitted.
[0077]
8, when the timer of the WDT 103 has counted a preset time, the WDT 103 outputs a reset signal e to the protocol controller 102, the comparison circuit 105, the CPU 106, and the MM 702. Next, the switching signal j is output to the switch 703 by the MM 702. Subsequently, the switch 703 connects the automatic response circuit 801 to the transceiver 101. Then, the automatic response circuit 801 transmits and receives data to and from the network. That is, even when the protocol controller 102 has stopped operating due to, for example, a hang-up, or even while the protocol controller 102 is being returned to the initial state by the reset signal e, data transmission / reception is performed by the automatic response circuit 801. It will be continued.
[0078]
As described above, according to the network connection device 800 of the present embodiment, the automatic response circuit 801 automatically responds when the protocol controller 102 stops transmitting and receiving data. Communication with the node can be continued without interruption.
[0079]
【The invention's effect】
As described above, according to the present invention, based on a general-purpose communication protocol, when the device is operating normally, transmission and reception of data with the network can be continued, while the device operates normally. If not, a network connection device that can be brought into a normal operation state by a reset signal can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram of a network connection device according to a first embodiment of this invention;
FIG. 2 is a diagram showing a network connection example of a node;
FIG. 3 is a diagram showing an example of message transfer between nodes;
FIG. 4 is a flowchart of each step of the network connection device according to the first embodiment of this invention;
FIG. 5 is a flowchart of each step of the watchdog timer according to the first embodiment of the present invention.
FIG. 6 is a block diagram of a network connection device according to a second embodiment of the present invention;
FIG. 7 is a block diagram of a network connection device according to a third embodiment of the present invention;
FIG. 8 is a block diagram of a network connection device according to a fourth embodiment of the present invention.
[Explanation of symbols]
100, 600, 700, 800 network connection device
101 transceiver
102 Protocol Controller
103 Watchdog timer
104 memory circuit
105 Comparison circuit
106 CPU
201 Logical ring
601, 701 status storage circuit
602 decoding circuit
702 monostable multivibrator
703 switch
801 Automatic response circuit

Claims (7)

A protocol control unit for transmitting / receiving a message conforming to a predetermined communication protocol to / from the network and controlling data transmission, a reset signal output unit for outputting a reset signal when a predetermined time is counted, and the protocol A network connection device, comprising: a timer control unit that stops timing the time when the message transmitted / received by the control unit matches a message stored in advance. When the message transmitted by the protocol control unit is a message that rejects any of the transmission of the data and the reception of the data, the timing control unit continues the timing of the time. Item 2. The network connection device according to item 1. A protocol control unit for transmitting / receiving a message conforming to a predetermined communication protocol to / from a network and controlling data transmission, wherein the protocol control unit transmits a message for rejecting any of the data transmission and the data reception. And a reset signal output means for outputting a reset signal when transmitted to the network. Operating state information storage means for storing operating state information indicating whether the circuit unit is in an operating state in which a predetermined range of circuit units is operating or in a stopped state in which operation is stopped. The network connection device according to any one of claims 1 to 3, wherein The network connection device according to claim 4, further comprising an operation state information transmitting unit that transmits the operation state information to the network. 6. The communication device according to claim 1, further comprising a message response unit that responds to the message from the network when the transmission and reception of the message is stopped. Network connection equipment. A reset signal output step of outputting a reset signal when a predetermined time is counted, and a timing stop step of stopping the time counting when the message transmitted / received to / from the network matches a message stored in advance. A method for resetting a network connection device, the method comprising:

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