WO2014061076A1

WO2014061076A1 - Communication system and communication device

Info

Publication number: WO2014061076A1
Application number: PCT/JP2012/076602
Authority: WO
Inventors: 幸亮尾形
Original assignee: 三菱電機株式会社
Priority date: 2012-10-15
Filing date: 2012-10-15
Publication date: 2014-04-24
Also published as: TW201415835A

Abstract

A communication system in which token passing is performed between a plurality of communication devices (100), wherein each time receiving a token frame, each of the communication devices (100) sets, in a reception WDT (1007), a time-out time that is a time longer than a time required for a token to circulate among the plurality of communication devices (100) and a time proportional to the number difference between the station number of a communication device (100) being the transmission source of the received token frame and the station number of the communication device itself. Each of the communication devices (100) receives a search frame from a detection communication device (100) that has detected that a communication device being the transfer destination of the token is not operating normally. Among the plurality of the communication devices (100), a communication device (100) in which a time-out occurred earliest after receiving the search frame generates, as a response to the search frame, an ACK frame that reports the station number of this communication device (100), and transmits the generated ACK frame to the detection communication device.

Description

Communication system and communication apparatus

The present invention relates to a communication system in which token passing is performed.
For example, the present invention relates to improving the availability of an industrial network that performs communication between communication devices using a token passing system.

In an industrial network, a token passing method is often adopted as a communication method as in Non-Patent Document 1.
In the token passing method, a token frame describing a transfer destination of a data transmission right always circulates in the network.
This data transmission right is called a token.
When the communication device that has received the token frame is the transfer destination of the data transmission right, the communication device acquires the data transmission right, stores the data in the token frame, and transmits the token frame to another communication device. .

Details of the token passing method will be described below.
It is assumed that a plurality of communication devices having one or more ports are connected by a full-duplex communication line.
As the connection configuration of the communication device, any configuration such as a ring, a line, and a star is allowed.
In addition, a switching hub can be used to connect the communication device.
Hereinafter, for convenience of explanation, it is assumed that five

communication devices

201, 202, 203, 204, and 205 are connected to one switching hub as illustrated in FIG.
Further, hereinafter, the communication device is also referred to as a station, the own device is referred to as the own station, and the other device is referred to as the other station.
In addition, when it is not necessary to distinguish between the communication device 201, the communication device 202, the communication device 203, the communication device 204, and the communication device 205, they are referred to as the communication device 200.

Each communication device 200 stores the number of its own station (hereinafter referred to as its own station number) and the number of the station to which the data transmission right (token) is to be transferred next (hereinafter referred to as a transfer destination station number).
Hereinafter, each communication device 200 uses the code number as its own station number.
In the example of FIG. 28, the local station number of the communication apparatus 201 is 201, and the transfer destination station number is 202.
The communication station 202 has its own station number 202 and the transfer destination station number 203.
The local station number of the communication apparatus 203 is 203, and the transfer destination station number is 204.
The local station number of the communication device 204 is 204, and the transfer destination station number is 205.
The communication station 205 has its own station number 205 and the transfer destination station number 201.
When each communication apparatus 200 acquires the data transmission right, each communication apparatus 200 stores the local station number and the transfer destination station number in the token frame and transmits the token frame.
In the example of FIG. 28, each communication device 200 obtains a data transmission right (token) in the order of (1) to (5).
That is, the data transmission right (token) circulates in the order of the communication device 201, the communication device 202, the communication device 203, the communication device 204, the communication device 205, and the communication device 201.

The format of the token frame is shown in FIG.
The frame identifier is an identifier indicating the type of frame, and stores an identifier of a token frame.
The destination station number indicates the destination of the token frame, and stores a value indicating all stations.
That is, the token frame is transmitted by broadcast.
In the transmission source station number, the station number of the communication apparatus 200 that is the transmission source of the token frame is stored.
In the transmission right transfer destination station number (hereinafter also simply referred to as transfer destination station number), the station number of the communication apparatus 200 to which the data transmission right (token) is transferred is stored.
The transmission data is data transmitted by the communication apparatus 200 that has acquired the data transmission right (token).
In addition, a checksum area for proving that the frame is not broken is at the end, but is omitted in the following description for the sake of simplicity.

Next, a configuration example of the communication apparatus 200 is shown in FIG.
The communication apparatus 200 includes a frame reception unit 2001, a frame transmission unit 2002, a token frame determination unit 2003, a reception data memory 2004, a token frame generation unit 2005, a transmission data memory 2006, a transfer destination station number storage register 2007, and a local station number storage register 2008. Composed.

The frame receiving unit 2001 receives a token frame transmitted from another station.

The token frame determination unit 2003 reads the transfer destination station number stored in the token frame from the other station and compares it with the value of the own station number storage register 2008.
As a result of the comparison, if the two match, the token frame determination unit 2003 instructs the token frame generation unit 2005 to transmit a token frame.
Further, the token frame determination unit 2003 transfers the transmission data in the received token frame to the reception data memory 2004 regardless of the comparison result.

The reception data memory 2004 stores transmission data in the received token frame.
The data stored in the reception data memory 2004 is used by a host control system connected to the communication apparatus 200.

The transmission data memory 2006 stores transmission data to be stored in a token frame transmitted from the own station.
Data stored in the transmission data memory 2006 is written from a host control system or the like.

The own station number storage register 2008 stores the own station number.
The user who uses the communication apparatus 200 writes the own station number using an engineering tool or the like in advance.

The transfer destination station number storage register 2007 stores the station number of the communication apparatus 200 to which the data transmission right (token) is transferred.
The transfer destination station number is written in advance by the user using the communication apparatus 200 using an engineering tool or the like.

The token frame generation unit 2005 receives an instruction from the token frame determination unit 2003, generates a token frame to be transmitted from the local station, and transfers the generated token frame to the frame transmission unit 2002.

The frame transmission unit 2002 transmits the token frame transferred from the token frame generation unit 2005 to another station.

Next, the token passing procedure will be described with reference to FIG.
A plurality of communication devices are connected in the configuration of FIG. 31, and the own station number and the transfer destination station number are set so that the data transmission right goes around in the order of the arrows, that is, in the order of the

communication devices

201, 202, 203, 204, 205. And
Further, the communication apparatus 201 first transmits a token.
In the following description, the contents of the token frame transmitted by the communication device are shown in the following format.
Token frame (transfer destination station number, own station number)
In the drawing, the token frame (transfer destination station number ← own station number) is represented as a token frame (202 ← 201).

(1) The communication apparatus 201 transmits a token frame (transfer destination station number: 202, own station number: 201).
The token frame is transmitted to all stations.

(2) In the communication apparatus 202, when the frame reception unit 2001 receives the token frame (transfer destination station number: 202, own station number: 201) from the communication apparatus 201, the token frame determination unit 2003 displays the token frame transfer destination station number. (= 202) and the value (= 202) of the local station number storage register 2008 are compared.
Since the two match, the communication apparatus 202 acquires the right to transmit data, and the token frame determination unit 2003 instructs the token frame generation unit 2005 to transmit a token frame.
In addition, the token frame determination unit 2003 transfers the transmission data in the token frame to the reception data memory 2004.

(3) In the communication device 202, the token frame generation unit 2005 generates a token frame (transfer destination station number: 203, own station number: 202), and the frame transmission unit 2002 transmits the token frame to all other stations.

(4) On the other hand, when receiving the token frame (transfer destination station number: 202, own station number: 201), the

communication devices

203, 204, and 205 compare the transfer destination station number of the data transmission right with the value of the own station number storage register. The token is not sent because they do not match.
However, the transmission data is transferred to the reception data memory 2004.

(5) Similarly, the

communication devices

203, 204, and 205 acquire the data transmission right in order and transmit token frames.
Finally, the communication apparatus 205 transmits a token frame (transfer destination station number: 201, own station number: 205), which is received by the communication apparatus 201 and acquires a data transmission right.
This completes the data transmission right.

Note that the station numbers of the communication device 200 are set in ascending order or descending order (not necessarily sequential numbers) in the order of the device that obtains the data transmission right.
That is, either the ascending order or descending order of the station numbers of the communication device 200 is designated as the token circulation order, and token passing is performed between the plurality of communication devices 200 according to the token circulation order.
In the following, it is assumed that the token circulation order is ascending.

When the communication device 200 becomes unable to transmit a token frame due to a failure, the data transmission right cannot be circulated first from the communication device 200.
For example, when the communication device 203 breaks down, the circulation of the data transmission right stops at the communication device 203, and thereafter other communication devices cannot communicate (FIG. 32).

In such a situation, as a method for maintaining the circulation of the data transmission right, the discontinuation and the reverse sequence are used.
The communication device 200 in which a failure has occurred is automatically excluded from the circulation of the data transmission right by an operation called “disconnection”.
In addition, when the communication device 200 in which a failure has occurred returns to normal due to device replacement or the like, the data transmission right circulation is automatically entered by an operation called return.

Specifically, the disconnection means that a communication device having a failed communication device as a transfer destination of the data transmission right temporarily changes the transfer destination of the data transmission right to a live (operating) communication device. (FIG. 33).
In the example of FIG. 33, since the communication device 203 has failed, the communication device 202 that has used the communication device 203 as the transfer destination of the data transmission right has changed the transfer destination of the data transmission right to the active communication device 204.
In addition, the reverse is that the communication device that temporarily changed the transfer destination of the data transmission right returns the transfer destination to the original when the communication device in which the failure occurred returns to normal due to device replacement or the like. (FIG. 34).
In the example of FIG. 34, since the communication device 203 in which the failure has occurred returns to normal, the communication device 202 that temporarily assigned the communication device 204 as the data transmission right transfer destination to the communication device 203 as the data transmission right transfer destination. It is returning.
Note that the communication device that is restored by the return must have the same local station number and transfer destination station number as those at the time of the previous departure.

Non-Patent Document 1 CC Link-IE is an example of an industrial network that supports disassembly and reconnection.
In the CC Link-IE, one master device in the network executes disassembly and return processing.
The master device knows the token transfer destination station numbers of all communication devices, and manages the transfer order in a list structure.
Then, the master device detects a failure of another communication device due to frame failure or the like, the master device searches the station number of the next live communication device from the list structure, and notifies the communication device of this station number information.
By this notification, the communication device having the failed communication device as the transfer destination of the data transmission right can temporarily change the transfer destination of the data transmission right to the live communication device.

As described above, in the method in which the master device centrally performs the disassembly and reversion, since the master device needs to manage the transfer order of the data transmission right in a list, a CPU (Central Processing) is used as a device that executes processing. (Unit).
If a CPU is adopted, the communication device is configured to implement token passing communication that strongly requires real-time performance by using ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array), while disclosing and A configuration in which the return is performed by the CPU is assumed.

From the viewpoint of cost reduction, it is desirable to make the communication device CPU-less and to implement token passing communication and sequence return in one ASIC or FPGA.
However, when the token passing communication and the sequence return are realized by one ASIC or FPGA, a large number of registers are required for list management, which is not preferable in terms of circuit area.

The present invention has been made in view of the above points, and has as its main object to eliminate the need for list management of token transfer order.

A communication system according to the present invention includes:
A communication system including a plurality of communication devices each having a device number set therein, wherein token passing is performed between the plurality of communication devices,
Each communication device
Have a timer to keep time,
Receiving a token frame broadcast from another communication device and notifying the device number of the other communication device and the device number of the communication device to which the other communication device assigns a token;
Each time a token frame is received, the timer is reset, and the device number of the communication device that is the transmission source of the received token frame that is longer than the time required for the token to make a round among the plurality of communication devices Set a time-out time, which is a time proportional to the difference between the device number and the device number of the own device, to the timer, and start counting the timer,
Receiving a search frame broadcast-transmitted from a detected communication device that has detected that the communication device to which the token is transferred is not operating normally;
Among the plurality of communication devices,
A communication device in which a timeout due to the elapse of a timeout time has occurred after receiving the search frame,
As a response to the search frame, generate a number notification frame that notifies the device number of the communication device,
The generated number notification frame is transmitted to the detection communication device.

According to the present invention, a communication device that has the earliest timeout after receiving a search frame among a plurality of communication devices detects a number notification frame that notifies the device number of the communication device as a response to the search frame. Send to communication device.
For this reason, the detection communication device can change the token transfer destination communication device by the number notification frame, and does not need to manage the token transfer order list.

FIG. 3 is a diagram illustrating a configuration example of a communication device having a disconnection function according to the first embodiment. FIG. 3 is a diagram showing a format example of a search frame according to the first embodiment. FIG. 4 is a diagram showing an example of the format of an ACK frame according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a method for disassembling according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a method for disassembling according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a method for disassembling according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a method for disassembling according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a method for disassembling according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a method for disassembling according to the first embodiment. FIG. 3 is a diagram illustrating an example of a plurality of disassembly lines according to the first embodiment. FIG. 3 is a diagram illustrating an example format of an attended frame according to the first embodiment. FIG. 4 is a diagram showing an example of an accept frame format according to the first embodiment. 3 is a diagram illustrating a configuration example of a communication device having a reverse function according to Embodiment 1. FIG. FIG. 3 is a diagram showing a state before returning according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a return method according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a return method according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a return method according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a return method according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a return method according to the first embodiment. FIG. 3 is a communication sequence diagram illustrating a return method according to the first embodiment. The figure which shows grouping of the token circuit which concerns on Embodiment 2. FIG. FIG. 3 is a flowchart showing an operation example of the communication apparatus according to the first embodiment. FIG. 3 is a flowchart showing a disconnection process of the communication device according to the first embodiment. FIG. 3 is a flowchart showing a disconnection process of the communication device according to the first embodiment. FIG. 3 is a flowchart showing a return processing of the communication apparatus according to the first embodiment. FIG. 3 is a flowchart showing an operation example of the communication apparatus according to the first embodiment. FIG. 3 is a diagram illustrating a hardware example of a communication device according to the first and second embodiments. The figure which shows the example of a connection of a communication apparatus. The figure which shows the example of a format of a token frame. The figure which shows the structural example of a communication apparatus. The figure which shows the example of a communication sequence by token passing. The figure which shows the example of the token passing at the time of failure of a communication apparatus. The figure which shows the concept of a disassembly. The figure which shows the concept of a return.

Embodiment 1 FIG.
In the present embodiment, the discontinuation and return processing is distributed to each communication device, so that list management becomes unnecessary, and token passing communication, the disassembly processing, and the return processing can be realized economically by ASIC or FPGA. Explain how it works.
In the following, differences from the prior art will be mainly described.

First, the method of disassembling will be described.
In the sequence, communication frames such as a search frame and an ACK frame are used in addition to the token frame.
The search frame is a communication frame transmitted by a communication device (hereinafter also referred to as a detection communication device) that has detected that a token transfer destination communication device (hereinafter also referred to as a token transfer destination communication device) is not operating normally. is there.
More specifically, when the token transfer destination communication device is not operating normally, the search frame is detected in the token circulation order among the station numbers of the normal communication device group excluding the token transfer destination communication device. This is a communication frame for requesting notification of a station number (new token transfer destination station number) that follows the station number of the apparatus.
The ACK frame is transmitted as a response to the search frame.
The ACK frame is a communication frame for notifying a station number of a new token transfer destination of the detection communication device, and corresponds to an example of a number notification frame.

The format of the search frame is as shown in FIG. 2, and includes a frame identifier, a transmission destination station number, a destination station number, a transmission source station number, and a final station flag.
The frame identifier is an identifier indicating that the frame is a search frame.
The destination station number stores a value indicating all stations as the transmission destination of the search frame.
That is, the search frame is broadcast to all stations.
The transmission source station number indicates the station number of the communication device that is the transmission source of the search frame.
The last station flag indicates whether the station number of the communication device that is the source of the search frame is greater than the station number of any other communication device, that is, the communication device that is the source of the search frame is the last in the token circulation order. Whether or not.
If there is another station with a station number larger than the station number of the communication device that is the source of the search frame (if it is not the last station), the final station flag is set to “0”, and the communication device that is the source of the search frame When the station number is the largest (when it is the last station), “1” is set in the last station flag.

Next, the format of the ACK frame is as shown in FIG. 3, and is composed of a frame identifier, a destination station number, a transmission source station number, and a response destination station number.
The frame identifier is an identifier indicating that the frame is an ACK frame.
In the destination station number, a value indicating all stations is stored as the transmission destination of the ACK frame.
That is, the ACK frame is broadcast to all stations.
The transmission source station number indicates the station number of the communication device that is the transmission source of the ACK frame.
The response destination station number indicates the station number of the communication device that is the source of the search frame.

A configuration example of the communication apparatus 100 for performing the disconnection is shown in FIG.
In FIG. 1, priority is given to ease of explanation, and only the components necessary for disassembly are described, and the components for reconnection are not described. 100 exists.
The components for returning will be described later.

In FIG. 1, a frame receiving unit 1001 receives various communication frames.
Specifically, the frame receiving unit 1001 receives a token frame, a search frame, and an ACK frame.
The frame receiving unit 1001 corresponds to an example of a token frame receiving unit, a search frame receiving unit, and a number notification frame receiving unit.

The token frame determination unit 1003 reads the transmission right transfer destination station number stored in the token frame from the other station and compares it with the value of the own station number storage register 1008.
As a result of the comparison, if the two match, the token frame determination unit 1003 instructs the token frame generation unit 1005 to transmit a token frame.
Further, the token frame determination unit 1003 transfers the transmission data in the received token frame to the reception data memory 1004 regardless of the comparison result.
The token frame determination unit 1003 resets a reception watchdog timer 1007 (hereinafter referred to as reception WDT 1007) every time a token frame (both addressed to the own station and other stations) is received, and receives a timeout time. Set to WDT1007.
The timeout time is longer than the time required for the token to make a round among the plurality of communication devices 100, and the station number and the local station number of the communication device that is the transmission source of the token frame received by the frame reception unit 1001 This is the time proportional to the number difference.
The token frame determination unit 1003 corresponds to an example of a timer control unit.

The reception data memory 1004 stores transmission data in the received token frame.
The data stored in the reception data memory 1004 is used by a host control system connected to the communication apparatus 100.

The transmission data memory 1006 stores transmission data to be stored in a token frame transmitted from the own station.
Data stored in the transmission data memory 1006 is written from an upper control system or the like.

The token frame generation unit 1005 receives an instruction from the token frame determination unit 1003, generates a token frame to be transmitted from the local station, and transfers the generated token frame to the frame transmission unit 1002.

The reception WDT 1007 is a watchdog timer that is reset by the token frame determination unit 1003 and sets a timeout time each time a token frame (both addressed to the own station and addressed to another station) is received.
Reception WDT 1007 corresponds to an example of a timer unit.

The own station number storage register 1008 stores the own station number.
The user who uses the communication apparatus 100 writes the own station number using an engineering tool or the like in advance.

The transfer destination station number storage register 1009 stores the station number (token transfer destination device number) of the communication device 100 to which the data transmission right (token) is transferred.
The transfer destination station number is written in advance by the user using the communication apparatus 100 using an engineering tool or the like.
The transfer destination station number storage register 1009 corresponds to an example of a transfer destination apparatus number storage unit.

The pre-release transfer destination station number storage register 1010 holds the token transfer destination station number value in a state where it has never been released (that is, holds the initial value of the transfer destination station number storage register 1009).

Search frame generation section 1011 generates a search frame when reception WDT 1007 times out due to the elapse of the timeout time.
That is, the search frame generation unit 1011 generates a search frame when it is detected that the communication apparatus to which the token is transferred is not operating normally due to a timeout of the reception WDT 1007.

Search frame determination section 1012 determines whether or not a frame received from another station is a search frame.
Further, the search frame determination unit 1012 receives the response waiting time by resetting the reception WDT 1007 when the frame received from another station is a search frame and the final station flag of the received search frame is “1”. Set to WDT1007.
Search frame determination unit 1012 also corresponds to an example of a timer control unit.

The ACK frame generation unit 1013 generates an ACK frame when the search frame determination unit 1012 confirms the reception of the search frame and when the reception WDT 1007 times out.
The ACK frame generation unit 1013 corresponds to an example of a number notification frame generation unit.

The ACK frame determination unit 1014 determines whether or not an ACK frame received from another station is addressed to the own station.
If the received ACK frame is addressed to the own station, the ACK frame determination unit 1014 updates the transfer destination station number in the transfer destination station number storage register 1009 to the station number notified by the ACK frame.
The ACK frame determination unit 1014 corresponds to an example of a transfer destination device number update unit.

The frame transmission unit 1002 transmits various communication frames.
Specifically, the frame transmission unit 1002 transmits a token frame, a search frame, and an ACK frame.
The frame transmission unit 1002 corresponds to an example of a token frame transmission unit, a search frame transmission unit, and a number notification frame transmission unit.

Also in the present embodiment, the station numbers of the communication apparatus 100 are set in ascending order or descending order (not necessarily sequential numbers) in the order of the apparatus that obtains the data transmission right (token).
That is, either the ascending order or descending order of the station numbers of the communication device 100 is designated as the token circulation order, and token passing is performed between the plurality of communication devices 100 according to the token circulation order.
In the following, it is assumed that the token circulation order is ascending.
Also, the format of the token frame is as shown in FIG.

Hereinafter, a sequence in which the communication apparatus 100 in FIG.
The sequence differs depending on the following two types of situations.
(A) When a communication device other than the last station (the station with the largest station number among the living stations) or the first station (the station with the smallest station number among the living stations) leaves due to a failure (FIG. 4, 5, 6)
(B) When the last station leaves due to a failure or when the first station leaves due to a failure (FIGS. 7, 8, 9)
Whether or not the own station is the final station is determined based on whether or not the own station number of the own station is larger than the transfer destination station number.
If the own station number is larger than the transfer destination station number, it is determined as the last station.
Hereinafter, a sequence for performing the separation in each of the situations (A) and (B) will be described.

(A) A case where a communication device other than the last station or the starting station is disconnected due to a failure will be described with reference to FIGS.
4, 5, and 6, a case is assumed in which the communication device 103 among the

communication devices

101, 102, 103, 104, and 105 becomes unable to communicate due to a failure.
4, 5, and 6, a procedure in which the communication apparatus 102 detects a failure of the communication apparatus 103 and changes the token transfer destination from the communication apparatus 103 to the communication apparatus 104 will be described.
Note that each of the

communication devices

101, 102, 103, 104, and 105 has the configuration shown in FIG.
The station numbers of the

communication apparatuses

101, 102, 103, 104, and 105 are the same as the reference numerals.
In other words, the local station number of the communication apparatus 101 is 101, and the transfer destination station number is 102.
The communication station 102 has its own station number 102 and the transfer destination station number 103.
The communication station 103 has its own station number 103 and the transfer destination station number is 104.
The local station number of the communication apparatus 104 is 104, and the transfer destination station number is 105.
The local station number of the communication apparatus 105 is 105, and the transfer destination station number is 101.
When it is not necessary to distinguish between the

communication devices

101, 102, 103, 104, and 105, they are expressed as the communication device 100.

In the following description, the contents of the token frame transmitted by the communication apparatus 100 are shown in the following format.
Token frame (transfer destination station number, own station number)
Further, in the drawing, the token frame (transfer destination station number ← own station number) is represented as a token frame (102 ← 101).
Also, (1) to (5) in FIGS. 4, 5, and 6 correspond to (1) to (5) in the following description.

(1) In the communication apparatus 102, when the frame reception unit 1001 receives the token frame (transfer destination station number: 102, transmission source station number: 101) from the communication apparatus 101, the token frame determination unit 1003 resets the reception WDT 1007. Then, a timeout time according to the following equation is set in the reception WDT 1007 (FIG. 4).
Timeout time = fixed value x abs (token station number-own station number)
In the above formula, abs is an operation for obtaining the absolute value of the value in ().
According to the above formula, the timeout time of the communication device 100 that has received the token frame is smaller as it is closer to the station number of the communication device 100 that is the transmission source of the token frame (that is, the device that obtains the data transmission right in the previous order). (The intention is described later in step (4)).
The reception WDT 1007 is reset every time a token frame from another communication apparatus 100 is received.
Further, the fixed value of the above expression is set to a sufficiently large value so that it does not time out before the next token frame arrives from another communication apparatus 100.
That is, the time-out time is a time longer than the time required for a token to make a round among the plurality of communication devices 100.
In FIG. 4, the timeout time when receiving the token frame from the communication device 101 is 10 (10 × 1) in the communication device 102, 30 (10 × 3) in the communication device 104, and in the communication device 105. 40 (10 × 4).

(2) The communication device 102 transmits a token frame (transfer destination station number: 103, transmission source station number: 102) with the communication device 103 (station number: 103) as a token transfer destination, but the communication device 103 cannot communicate due to a failure. (Fig. 4).
For this reason, no token frame is transmitted from the communication device 103.
Therefore, the reception WDT 1007 of the communication apparatus 102 does not reset and eventually times out.
Then, the search frame generation unit 1011 of the communication apparatus 102 detects a timeout, regards that the communication apparatus 103 has left due to a failure, and searches for a subsequent (higher station number) live station (search frame (source station number)). : 102, final station flag: 0), and the frame transmission unit 1002 broadcasts the search frame.
Here, there is a concern that a communication device other than the communication device 102 may time out first.
However, since the reception WDTs 1007 of communication devices other than the communication device 102 are simultaneously reset by the token frame transmitted by the communication device 102, the reception WDT 1007 of the communication device 102 that has timed before the transmission of the token frame always times out first. .

(3) When the frame reception unit 1001 of a communication device other than the communication device 102 receives a search frame from the communication device 102, the search frame determination unit 1012 determines the content of the search frame, and the search frame transmission source station number (= 102) ) Is larger than the own station number, the reception WDT 1007 is reset (FIG. 4).
This will not cause a timeout.
Specifically, the communication apparatus 101 (own station number: 101) resets the reception WDT 1007.
Since the purpose of the search frame is for the communication device 102 to search for a subsequent live station (having a larger station number), the communication device 101 should not try to disconnect even if it receives the search frame from the communication device 102. .
On the other hand, when the transmission frame number of the search frame is smaller than the own station number (specifically, communication device 104 and communication device 105), search frame determination unit 1012 does not reset reception WDT 1007.
Communication device 102 retransmits the search frame until an ACK frame is received (FIG. 5).

(4) The reception WDT 1007 of the communication device 104 and the communication device 105 is decremented without being reset, and the reception WDT 1007 of the communication device 104 eventually times out (FIG. 5).
This is because when the communication device 104 and the communication device 105 receive the token frame transmitted from the communication device 102 in the procedure (2), the reception WDT 1007 of the communication device 104 sets a smaller timeout time.
In FIG. 4, the timeout time when the token frame is received from the communication device 102 is 20 (10 × 2) in the communication device 104 and 30 (10 × 3) in the communication device 105.
Thus, the station to which the reception WDT 1007 first times out is the station that is closest in number to the station that has failed.
In communication apparatus 104, when the time-out of reception WDT 1007 and the condition for receiving a search frame from another station are satisfied, search frame determination unit 1012 instructs ACK frame generation unit 1013 to generate an ACK frame.
The ACK frame generation unit 1013 generates an ACK frame (response destination station number: 102, transmission source station number: 104), and the frame transmission unit 1002 transmits the ACK frame.

(5) In the communication device 102, the ACK frame determination unit 1014 determines whether or not the ACK frame is addressed to the own station with reference to the response destination station number of the ACK frame received from the communication device 104 (station number: 104). If it is addressed to a station, the token transfer destination station number in the transfer destination station number storage register 1009 is changed to the station number (station number: 104) of the transmission source of the ACK frame (FIG. 6).
Further, the token frame generation unit 1005 generates a token frame (transfer destination station number: 104, transmission source station number: 102) according to the new token transfer destination station number of the transfer destination station number storage register 1009.
Then, the frame transmission unit 1002 broadcasts the token frame (transfer destination station number: 104, transmission source station number: 102).
Thereafter, when the data transmission right is acquired, the communication apparatus 102 generates a token frame (transfer destination station number: 104, transmission source station number: 102) and broadcasts it.
Further, when the

communication apparatuses

101 and 105 receive the ACK frame from the communication apparatus 104 and confirm that the received ACK frame is not addressed to the local station, the

communication apparatuses

101 and 105 reset the reception WDT 1007 and set the timeout time to the reception WDT 1007 again. Set (FIG. 6).

(B) When the last station leaves due to failure, or when the first station leaves due to failure Assuming the case where the last station leaves, explanation will be given with reference to FIGS.
7, 8, and 9, it is assumed that the communication device 105 out of the

communication devices

101, 102, 103, 104, and 105 becomes unable to communicate due to a failure.
7, 8, and 9, a procedure in which the communication apparatus 104 detects a failure of the communication apparatus 105 and changes the token transfer destination from the communication apparatus 105 to the communication apparatus 101 will be described.
Note that (1) to (5) in FIGS. 7, 8, and 9 correspond to (1) to (5) in the following description.

(1) The communication device 104 transmits a token frame (transfer destination station number: 105, transmission source station number: 104) to the communication device 105 (station number: 105), but the communication device 105 is unable to communicate due to a failure. Therefore, no token frame is transmitted from the communication device 105.
Therefore, the reception WDT 1007 of the communication device 104 does not reset and eventually times out (FIG. 7).
Then, the search frame generation unit 1011 of the communication device 104 detects a time-out, considers that the communication device 105 has left due to a failure, and searches for a subsequent live station (source frame number: 104, last station flag). : 0), and the frame transmission unit 1002 broadcasts the search frame.

(2) However, at present, only the

communication devices

101, 102, and 103 having a station number smaller than that of the communication device 104 are alive, and the

communication devices

101, 102, and 103 receive the reception WDT 1007 even if the search frame is received from the communication device 104. It only resets.
Therefore, none of the

communication devices

101, 102, and 103 returns an ACK frame.
Therefore, when the communication device 104 does not return an ACK frame even if the search frame is retransmitted a specified number of times (FIG. 7), the token frame generation unit 1005 determines that the local station is at the end in the token circulation order, and finally A search frame (transmission source station number: 104, final station flag: 1) with a station flag of “1” is generated, and the frame transmission unit 1002 broadcasts this search frame (FIG. 8).
The search frame whose final station flag is “1” corresponds to an example of the last notification frame.
The communication apparatus 104 also changes the retransmission period of the search frame, and takes it long enough to cause a timeout of the reception WDT 1007 at another station (previously the period was such that no timeout occurred).

(3) When

communication devices

101, 102, and 103 receive a search frame (source station number: 104, final station flag: 1) from communication device 104, search frame determination unit 1012 resets reception WDT 1007, and The response waiting time is set in the reception WDT 1007 with the value of (FIG. 8).
Response waiting time = fixed value × own station number According to the above equation, a shorter response waiting time is set in the reception WDT 1007 for a communication device with a smaller station number.
In FIG. 8, the response waiting time of the communication device 101 is 10 (10 × 1), the response waiting time of the communication device 102 is 20 (10 × 2), and the response waiting time of the communication device 103 is 30 (10 × 1). 3).

(4) After that, in the communication device with the smallest station number (communication device 101 in this example), the reception WDT 1007 times out first (FIG. 8).
In communication apparatus 101 in which reception WDT 1007 times out, ACK frame generation unit 1013 generates an ACK frame (response destination station number: 104, transmission source station number: 101), and frame transmission unit 1002 broadcasts the ACK frame.

(5) In the communication device 104, the ACK frame determination unit 1014 determines whether the earliest ACK frame (here, the ACK frame from the communication device 101) is addressed to the local station, and the ACK frame is If it is addressed to the station, the token transfer destination station number in the transfer destination station number storage register 1009 is changed to the station number (station number: 101) of the transmission source of the ACK frame (FIG. 9).
The token frame generation unit 1005 generates a token frame (transfer destination station number: 101, transmission source station number: 104) according to the new token transfer destination station number of the transfer destination station number storage register 1009.
Then, the frame transmission unit 1002 broadcasts a token frame (transfer destination station number: 101, transmission source station number: 104).
Thereafter, when the data transmission right is acquired, the communication device 104 generates a token frame (transfer destination station number: 101, transmission source station number: 104), and broadcasts it.
Further, when the

communication apparatuses

102 and 103 receive the ACK frame from the communication apparatus 101 and confirm that the received ACK frame is not addressed to the local station, the

communication apparatuses

102 and 103 reset the reception WDT 1007 and set the timeout time to the reception WDT 1007 again. Set (FIG. 8).

As a result of the above, we have been able to disconnect from the last station that has left.

Further, when the starting station (communication apparatus 101 in this example) leaves, the last station (communication apparatus 105 in this example) transmits a search frame. In this case as well, the procedure (2) described above is performed. Since the situation is the same as above, disassembly can be performed by the same procedure as described above.

Note that even when a plurality of communication devices with consecutive station numbers are disconnected (FIG. 10), disconnection is possible.
In this case, one communication device may perform the disconnection a plurality of times.

Next, a method for returning will be described.
In the reverse sequence, communication frames such as an attend frame and an accept frame are used in addition to the token frame.
The attended frame is a broadcast that is broadcast from a communication device (hereinafter also referred to as an unsubscribed communication device) that is included in the communication system (network) but has not subscribed to token passing, and is notified of the station number of the unsubscribed communication device. It is a frame.
The accept frame is a communication frame for notifying that an unsubscribed communication device is approved to participate in token passing.

The format of the attended frame is as shown in FIG. 11, and is composed of a frame identifier, a destination station number, and a transmission source station number.
The frame identifier is an identifier indicating that the frame is an attended frame.
The destination station number stores a value indicating all stations as the transmission destination of the attended frame.
That is, the attended frame is broadcast to all stations.
The transmission source station number indicates the station number of the communication apparatus 100 that is the transmission source of the attended frame.

Next, the format of the accept frame is as shown in FIG. 12, and includes a frame identifier, a destination station number, a transmission source station number, and a final station flag.
The frame identifier is an identifier indicating that the frame is an accept frame.
The destination station number indicates the station number of the communication apparatus 100 that is the transmission source of the attended frame.
That is, the accept frame is unicast to the transmission source of the attended frame.
The transmission source station number indicates the station number of the communication device that is the transmission source of the accept frame.
The final station flag indicates whether the station number of the communication device that is the source of the accept frame is greater than the station number of any other communication device, that is, the communication device that is the source of the accept frame is the last in the token circulation order. Whether or not.
If there is another station with a station number larger than the station number of the accepting frame transmission source communication device (if it is not the last station), the final station flag is set to “0” and the accept frame transmitting source communication device When the station number is the largest (when it is the last station), “1” is set in the last station flag.

FIG. 13 shows the configuration of the communication apparatus 100 for performing the reverse sequence.
In FIG. 13, priority is given to ease of explanation, and only the components necessary for reverse sequence are described, and the components for disconnection (FIG. 1) are not described. Are also present in the same communication apparatus 100.

The frame receiving unit 1001 is shown in FIG. 1 and receives various communication frames.
In the reverse processing, the frame receiving unit 1001 receives a token frame, an attended frame, and an accept frame.
The frame receiving unit 1001 corresponds to an example of an attended frame receiving unit.

The token frame determination unit 1003, reception data memory 1004, token frame generation unit 1005, transmission data memory 1006, own station number storage register 1008, transfer destination station number storage register 1009, and transfer destination station number storage register 1010 before release are shown in FIG. The description is omitted.

The transmission watchdog timer 1055 (hereinafter referred to as transmission WDT 1055) is a watchdog timer that is reset when the local station acquires the right to transmit data and transmits a token frame.

The attended frame generation unit 1051 generates an attended frame when the transmission WDT 1055 times out.

The attended frame determination unit 1052 determines whether a frame received from another station is an attended frame.
If the received attend frame is addressed to the own station, the attend frame determination unit 1052 sets the transfer destination station number in the transfer destination station number storage register 1009 to the station number notified by the attend frame (the station number of the unsubscribed communication device). Update.
The attended frame determination unit 1052 corresponds to an example of a transfer destination device number update unit.

The accept frame generating unit 1053 generates an accept frame when reception of the attended frame is confirmed by the attended frame determining unit 1052 and an accept frame transmission condition described in the description of the return sequence described later is satisfied.

The accept frame determination unit 1054 determines whether an accept frame received from another station is addressed to the own station.

The frame transmission unit 1002 is the one shown in FIG. 1 and transmits various communication frames.
Specifically, in the reverse processing, the frame transmission unit 1002 transmits a token frame, an attended frame, and an accept frame.
The frame transmission unit 1002 corresponds to an example of a token frame transmission unit and an accept frame transmission unit.

Hereinafter, assuming that the

communication devices

101, 103, 104, and 106 are disconnected from the six

communication devices

101, 102, 103, 104, 105, and 106, as shown in FIG. A method will be described.
Each of the

communication devices

101, 102, 103, 104, 105, 106 has the configuration shown in FIG.
The station numbers of the

communication apparatuses

101, 102, 103, 104, 105, and 106 are the same as the codes.
The method of returning is different depending on the position of the communication device to be returned.

(A) When a communication device other than the last station restores the restored communication device (FIGS. 15 and 16)
(B) When the communication device that has become the final station due to the last station or disconnection returns a communication device having a larger station number than itself (FIGS. 17 and 18)
(C) A case where a communication device that has become the last station due to the last station or disconnection returns a communication device having a station number smaller than itself (FIGS. 19 and 20).
Hereinafter, the method of returning will be described for each.

(A) When a communication device other than the last station restores the restored communication device As shown in FIGS. 15 and 16, it is assumed that the communication device 103 is restored and the communication device 102 executes the restoration process.
Note that (1) to (6) in FIGS. 15 and 16 correspond to (1) to (6) in the following description.

(1) When the communication apparatus 103 recovers from the failure, the communication apparatus 103 resets the transmission WDT 1055 and sets the timeout time to the transmission WDT 1055 (FIG. 15).
The timeout time of the transmission WDT 1055 is longer than the time required for the data transmission right to go around the six communication devices.

(2) Since the data transmission right does not reach the communication device 103, the transmission WDT 1055 eventually times out (FIG. 15).
Then, the attended frame generating unit 1051 of the communication apparatus 103 generates an attended frame (transmission source station number: 103), and the frame transmitting unit 1002 broadcasts the attended frame.
Also, the attended frame generation unit 1051 resets the transmission WDT 1055 and sets the timeout time again.

(3) When a communication device other than the communication device 103 receives an attended frame, the attended frame determination unit 1052 performs a condition determination on the following accept frame transmission condition (α). The accept frame generation unit 1053 generates an accept frame, and the frame transmission unit 1002 transmits the accept frame (FIG. 15).
Accept frame transmission condition (α):
(Α1) The own station is not the final station (α2) Current transfer destination station number ≠ transfer destination station number before disconnection This means that the own station is in a state where another station is disconnected.
(Α3) own station number <source station number of received attended frame (α4) source station number of received attended frame <current transfer destination station number The conditions of (α3) and (α4) are: This means that there is a station that has returned to the other station.

In this example, the communication apparatus 102 satisfies the above conditions, and the communication apparatus 102 transmits an accept frame (destination station number: 103, transmission source station number: 102).
Also, the attended frame determination unit 1052 of the communication apparatus 102 rewrites the token transfer destination station number in the transfer destination station number storage register 1009 to the transmission source station number (station number: 103) of the attended frame.

(4) When receiving the accept frame, the communication device 103 resets the transmission WDT 1055.
If the communication device 103 cannot receive the accept frame and the transmission WDT 1055 times out, it retransmits the attended frame.

(5) When the next data transmission right is acquired, the communication apparatus 102 generates a token frame (transfer destination station number: 103, transmission source station number: 102) in accordance with the new token transfer destination station number in the transfer destination station number storage register 1009 ( FIG. 16).
Then, the frame transmission unit 1002 broadcasts the token frame (transfer destination station number: 103, transmission source station number: 102).

(6) Next, the communication apparatus 103 acquires a data transmission right (FIG. 16).
Here, even when the communication device 103 executes the disconnection before leaving and the transfer destination station number storage register 1009 is rewritten from the initial value, the initial value (the transfer destination station number storage register 1010 before the release) is restored. ) Is the token transfer destination station number.
For this reason, when the default transfer destination station is still leaving, the communication apparatus 103 performs the disconnection process again.

(B) When the communication device that has become the final station due to the last station or disconnection returns a communication device having a larger station number than itself, as shown in FIGS. 17 and 18, the communication device 106 returns and the communication device 105 recovers. Assume that column processing is executed.
Note that (1) to (6) in FIGS. 17 and 18 correspond to (1) to (6) in the following description.

(1) When the communication device 106 recovers from the failure, the communication device 106 resets the transmission WDT 1055 and sets the timeout time to the transmission WDT 1055 (FIG. 17).
The timeout time of the transmission WDT 1055 is longer than the time required for the data transmission right to go around the six communication devices.

(2) Since the data transmission right does not go to the communication device 106, the transmission WDT 1055 eventually times out (FIG. 17).
Then, the attended frame generating unit 1051 of the communication apparatus 106 generates an attended frame (transmission source station number: 106), and the frame transmitting unit 1002 broadcasts the attended frame.
Also, the attended frame generation unit 1051 resets the transmission WDT 1055 and sets the timeout time again.

(3) When a communication device other than the communication device 106 receives an attended frame, the attended frame determination unit 1052 performs a condition determination on the following accept frame transmission condition (β). The accept frame generation unit 1053 generates an accept frame, and the frame transmission unit 1002 transmits the accept frame (FIG. 17).
Accept frame transmission condition (β):
(Β1) The own station is the final station (β2) The own station number <the transmission source station number of the received attended frame In this example, the communication device 105 satisfies the above conditions, and the communication device 105 receives an accept frame (destination station number: 106, Source station number: 105) is transmitted.
Also, the attended frame determination unit 1052 of the communication device 105 rewrites the token transfer destination station number in the transfer destination station number storage register 1009 to the transmission source station number (station number: 106) of the attended frame.

(4) When receiving the accept frame, the communication device 106 resets the transmission WDT 1055.
If the accept frame cannot be received and the transmission WDT 1055 times out, the communication apparatus 106 retransmits the attended frame.

(5) When acquiring the next data transmission right, the communication apparatus 105 generates a token frame (transfer destination station number: 106, transmission source station number: 105) according to the new token transfer destination station number in the transfer destination station number storage register 1009 ( FIG. 18).
Then, the frame transmission unit 1002 broadcasts the token frame (transfer destination station number: 106, transmission source station number: 105).

(6) Next, the communication device 106 acquires the data transmission right (FIG. 18).
Here, even if the communication device 106 has been disconnected before leaving, and the transfer destination station number storage register 1009 has been rewritten from the initial value, the initial value (transfer destination station number storage register 1010 before release) is restored. ) Is the token transfer destination station number.
For this reason, when the default transfer destination station is still leaving, the communication device 106 performs the disconnection process again.

(C) When the communication device that has become the final station due to the last station or disconnection returns a communication device having a station number smaller than that of itself, as shown in FIGS. Assume that column processing is executed.
Note that (1) to (5) in FIGS. 19 and 20 correspond to (1) to (5) in the following description.

(1) When the communication apparatus 101 recovers from the failure, the communication apparatus 101 resets the transmission WDT 1055 and sets the timeout time to the transmission WDT 1055 (FIG. 19).
The timeout time of the transmission WDT 1055 is longer than the time required for the data transmission right to go around the six communication devices.

(2) Since the right to transmit data does not reach the communication device 101, the transmission WDT 1055 times out (FIG. 19).
Then, the attended frame generating unit 1051 of the communication apparatus 101 generates an attended frame (transmission source station number: 101), and the frame transmitting unit 1002 broadcasts the attended frame.
Also, the attended frame generation unit 1051 resets the transmission WDT 1055 and sets the timeout time again.

(3) When a communication device other than the communication device 101 receives an attended frame, the attended frame determination unit 1052 performs a condition determination on the following accept frame transmission condition (γ). The accept frame generation unit 1053 generates an accept frame, and the frame transmission unit 1002 transmits the accept frame (FIG. 19).
Accept frame transmission condition (γ):
(Γ1) The local station is the final station (γ2) The transmission source station number of the received attended frame <the token transfer destination station number of the local station

In this example, the communication apparatus 105 satisfies the above conditions, and the communication apparatus 105 transmits an accept frame (destination station number: 101, transmission source station number: 105).
Also, the attended frame determination unit 1052 of the communication device 105 rewrites the token transfer destination station number in the transfer destination station number storage register 1009 to the attended frame transmission source station number (station number: 101).

(4) Upon receiving the accept frame, the communication apparatus 101 resets the transmission WDT 1055.
If the communication apparatus 101 cannot receive the accept frame and the transmission WDT 1055 times out, it retransmits the attended frame.

(5) When acquiring the next data transmission right, the communication device 105 generates a token frame (transfer destination station number: 101, source station number: 105) according to the new token transfer destination station number in the transfer destination station number storage register 1009 ( FIG. 20).
Then, the frame transmission unit 1002 broadcasts the token frame (transfer destination station number: 101, transmission source station number: 105).

Next, an operation example of the communication apparatus 100 illustrated in FIGS. 1 and 13 will be described using a flowchart.
The overall operation of the communication apparatus 100 will be described with reference to FIG.

First, when the frame reception unit 1001 receives a communication frame, the frame reception unit 1001 outputs the received communication frame to the token frame determination unit 1003.
Then, the token frame determination unit 1003 determines whether or not the received communication frame is a token frame (S101).
If the received communication frame is a token frame (YES in S101), the token frame determination unit 1003 resets the reception WDT 1007 and sets the timeout time to the reception WDT 1007 (S102).
Further, the token frame determination unit 1003 determines whether or not the received token frame is a token frame addressed to the own station (S103).
If the received token frame is a token frame addressed to the own station (YES in S103), the token frame generation unit 1005 is instructed to generate a token frame.
Then, the token frame generation unit 1005 generates a token frame, and the frame transmission unit 1002 broadcasts the token frame (S104).

On the other hand, when the communication frame received by the frame receiving unit 1001 is not a token frame (NO in S101) and is an attended frame (YES in S105), a return process is performed (S106).
Details of the return processing will be described later.

Further, when the frame receiving unit 1001 has not received any token frame, attended frame, or search frame (NO in S101, NO in S105, NO in S107), and a timeout of the reception WDT 1007 occurs (YES in S108) In this case, the disassembling process (1) is performed (S109).
Details of the disassembling process (1) will be described later.

Further, when the frame receiving unit 1001 receives a search frame (NO in S101, NO in S105, YES in S107), a dissecting process (2) is performed (S110).
Details of the disassembling process (2) will be described later.

FIG. 23 is a flowchart showing details of the disassembling process (1).
As described above, when the frame receiving unit 1001 has not received any of the token frame, the attended frame, or the search frame (NO in S101, NO in S105, NO in S107), and the reception WDT 1007 times out (S108) 23), the flow of FIG. 23 starts.

First, the search frame generation unit 1011 generates a search frame whose final station flag is “0”, and the frame transmission unit 1002 broadcasts the search frame (S1091).
Next, when the frame reception unit 1001 receives a communication frame, the ACK frame determination unit 1014 analyzes the received communication frame.
If the received communication frame is an ACK frame for the search frame (last station flag: 0) transmitted in S1091, (YES in S1092), the ACK frame determination unit 1014 transfers the token in the transfer destination station number storage register 1009. The previous station number is changed to the station number of the transmission source of the ACK frame (S1096).
Further, the token frame generation unit 1005 generates a token frame according to the new token transfer destination station number in the transfer destination station number storage register 1009, and the frame transmission unit 1002 broadcasts the token frame (S1097).

On the other hand, when an ACK frame is not received (NO in S1092), the frame transmission unit 1002 retransmits the search frame (last station flag: 0) (S1091) until the specified number of retransmissions is reached (S1093).
If the ACK frame is not received even after the specified number of retransmissions (YES in S1093), the search frame generation unit 1011 generates a search frame with the final station flag “1”, and the frame transmission unit 1002 receives the search frame. Is broadcast (S1094).
When the frame reception unit 1001 receives an ACK frame for the search frame (last station flag: 1) (S1095), the ACK frame determination unit 1014 sets the token transfer destination station number in the transfer destination station number storage register 1009 to the transmission source of the ACK frame. (S1096).
Further, the token frame generation unit 1005 generates a token frame according to the new token transfer destination station number in the transfer destination station number storage register 1009, and the frame transmission unit 1002 broadcasts the token frame (S1097).

FIG. 24 is a flowchart showing details of the disassembling process (2).
As described above, when the frame receiving unit 1001 receives a search frame (NO in S101, NO in S105, YES in S107), the flow in FIG. 23 starts.

First, the search frame determination unit 1012 compares the transmission source station number of the search frame with its own station number (S1101), and if the own station number is larger than the transmission station number of the search frame (NO in S1101), the time-out of the reception WDT 1007 When this occurs (YES in S1102), the ACK frame generation unit 1013 generates an ACK frame, and the frame transmission unit 1002 broadcasts the ACK frame (S1103).
The response destination station number of the ACK frame is the source station number of the search frame.

On the other hand, if the frame receiving unit 1001 receives an ACK frame before the reception WDT 1007 times out (NO in S1102 and YES in S1104), the received ACK frame is not addressed to the own station, so the token frame determining unit 1003 Resets the reception WDT 1007 and sets the timeout time again (S1105).

If the transmission source station number of the search frame is larger than the own station number in S1101 (YES in S1101), the search frame determination unit 1012 resets the reception WDT 1007 and sets the timeout time again (S1106).
Further, when the frame reception unit 1001 receives a search frame with the final station flag “1” (YES in S1107), the search frame determination unit 1012 resets the reception WDT 1007, and the procedure (3) in FIG. The response waiting time described is set (S1108).
If the response waiting time set in S1108 elapses and the reception WDT 1007 times out (YES in S1109), the ACK frame generation unit 1013 generates an ACK frame, and the frame transmission unit 1002 broadcasts the ACK frame. (S1103).
On the other hand, when the frame receiving unit 1001 receives an ACK frame without receiving a search frame (last station flag: 1) (NO in S1107, YES in S1110), the received ACK frame is not addressed to the own station. Therefore, the token frame determination unit 1003 resets the reception WDT 1007 and sets the timeout time again (S1111).

FIG. 25 is a flowchart showing details of the reverse processing.
As described above, when the frame reception unit 1001 receives an attended frame (YES in S105), the flow in FIG. 25 starts.

First, the attended frame determination unit 1052 determines whether any of the accept frame transmission conditions (α), (β), and (γ) is satisfied for the local station (S1061).
If any one of the accept frame transmission conditions is satisfied (YES in S1061), the accept frame generation unit 1053 generates an accept frame, and the frame transmission unit 1002 unicasts the accept frame (S1062).
Furthermore, the attended frame determination unit 1052 rewrites the token transfer destination station number in the transfer destination station number storage register 1009 with the transmission source station number of the attended frame (S1063).

FIG. 26 is a flowchart illustrating an operation example of the communication apparatus 100 that has recovered from a failure.

First, the token frame generation unit 1005 resets the transmission WDT 1055 and sets a timeout time (S201).
When the transmission WDT 1055 times out (YES in S202), the attended frame generating unit 1051 generates an attended frame, and the frame transmitting unit 1002 broadcasts the attended frame (S203).
Further, the attended frame generation unit 1051 resets the transmission WDT 1055 and sets a timeout time again (S204).

If the frame receiving unit 1001 receives the accept frame before the time-out occurs and the accept frame determining unit 1054 confirms that the received accept frame is addressed to the own station, the process proceeds to S101 (S207).
As a result, the communication apparatus 100 participates in token passing.
On the other hand, when a timeout occurs (YES in S206), the frame transmission unit 1002 retransmits the attended frame.

As described above, according to the present embodiment, the discontinuation and return processing are distributed to each communication device, thereby eliminating the need for intensive list management in one conventional communication device, and token passing communication. In addition, it is possible to economically realize the disassembling process and the returning process by ASIC or FPGA.

Embodiment 2. FIG.
Even when there are a plurality of token loops in one network, the disassembling method and the returning method described in the first embodiment are effective.
For example, as shown in FIG. 21, the

communication devices

101, 102, 103, 104, 105, and 106 are connected to the same network, and the

communication devices

101, 102, and 103 have one closed token circulation. A situation where the

communication devices

104, 105, 106 form another closed token circuit.

When a plurality of token circuits are mixed, a group number area exists in the token frame, and a different group number is assigned to each closed token circuit (FIG. 21).
Each communication apparatus 100 refers to the group number when receiving the token frame, and discards the received token frame when the referred group number is different from the group number of the group to which the own station belongs.
This prevents data transmission rights from being obtained even if a token frame is received from another group.

Even in such a network, by referring to a group number of a frame (search frame, ACK frame, attended frame, and accept frame) in the process of de-sequence and re-sequence, the de-sequence and the sequence can be performed only in one closed token circuit. Returning is possible.

As described above, in the first and second embodiments,
Multiple communication devices with one or more ports are connected via a full-duplex communication line.
As a means of data communication, a token passing system in which a token frame circulates around the network at all times, a communication device that captures the token frame acquires the right to transmit data, includes data in the token frame, and transmits it to other communication devices. Explained the adopted network.

In the first and second embodiments,
Each communication device
A frame receiver for receiving a token frame transmitted from another station;
A token frame determination unit that reads out the transfer destination station number stored in the token frame from another station and compares it with the value of the own station number storage register;
A reception data memory for storing transmission data of the received token frame;
A transmission data memory for storing transmission data stored in a token frame transmitted from the own station;
A local station number storage register for storing the local station number;
A transfer destination station number storage register for storing the transfer destination station number of the data transmission right;
In response to an instruction from the token frame determination unit, a token frame generation unit that generates a token frame to be transmitted from the own station;
A frame transmission unit for transmitting the token frame transferred from the token frame generation unit to another station;
A reception watchdog timer that is a watchdog timer that is reset when a token frame is received;
When the reception watchdog timer times out, a search frame generation unit that generates a search frame;
A search frame determination unit that determines whether the received frame is a search frame;
An ACK frame generation unit that generates an ACK frame under the search frame reception and reception watchdog timer timeout conditions;
An ACK frame determination unit for determining whether the received ACK frame is addressed to the own station;
Pre-release transfer destination station number storage register holding the initial setting value of the transfer destination station number storage register;
We explained that we have.

In the first and second embodiments,
Each communication device
A transmission watchdog timer, which is a watchdog timer that is reset when the local station transmits a token frame,
When the transmission watchdog timer times out, an attended frame generator that generates an attended frame,
An attended frame determination unit that determines whether the received frame is an attended frame;
When the attendee frame is received, the current transfer destination station number does not match the transfer destination station number before the release, the transmission source station number of the attended frame received from the own station number is larger, and the transmission source station number of the received attendance frame An accept frame generation unit that generates an accept frame when the current transfer destination station number is larger;
An accept frame determination unit for determining whether the received accept frame is addressed to the own station;
We explained that we have.

In the first and second embodiments,
Each communication device broadcasts a search frame when the reception watchdog timer times out,
A communication device whose station number is larger than the communication device that broadcasts the search frame and the reception watchdog timer timed out first, receives the search frame, and transmits an ACK frame to the communication device that broadcasts the search frame. Hereinafter, it has been described that the defective communication device is excluded from the transfer destination of the data transmission right.

In the first and second embodiments,
Each communication device resets the transmission watchdog timer when it recovers from the failure, broadcasts an attended frame when the transmission watchdog timer times out,
The current token transfer destination station number does not match the token transfer destination station number before the release, the station number of the communication device that broadcasts the attended frame is larger than the own station number, and the station number of the communication device that broadcasts the attended frame The communication device that satisfies the condition that the token transfer destination station number of its own communication device is larger receives the attend frame and sends an accept frame to the communication device that broadcasts the attend frame. Explained changing to a communication device that has recovered from a problem.

Finally, a hardware configuration example of the communication apparatus 100 shown in the first and second embodiments will be described with reference to FIG.
As a hardware configuration of the communication device 100, an arithmetic device 901, an external storage device 902, a main storage device 903, a communication device 904, and an input / output device 905 are connected to the bus.

The arithmetic device 901 is, for example, an ASIC or FPGA.
Further, the arithmetic device 901 can be a CPU.
The external storage device 902 is, for example, a ROM (Read Only Memory), a flash memory, or a hard disk device.
The main storage device 903 is a RAM (Random Access Memory) or a register. Correspond.
The communication device 904 corresponds to the physical layer of the frame reception unit 1001 and the frame transmission unit 1002.
The input / output device 905 is, for example, a mouse, a keyboard, a display device, or the like.

1 to 13 is realized by, for example, an ASIC or FPGA circuit and wiring.
When the arithmetic unit 901 is a CPU, “˜unit” in FIGS. 1 and 13 is a program, and the CPU executes these programs to realize the function of “˜unit”.
The program is normally stored in the external storage device 902, and is loaded into the main storage device 903 and sequentially read into the arithmetic device 901 and executed.
In the description of the first and second embodiments, “determining”, “determining”, “extracting”, “detecting”, “setting of”, “registering”, “ Information, data, signal values, and variable values that indicate the results of the processing described as “selection of”, “update of”, “generation of”, “input of”, “output of”, etc. It is stored as a file in the device 903.
Further, the encryption key / decryption key, random number value, and parameter may be stored in the main storage device 903 as a file.

The configuration in FIG. 27 is merely an example of the hardware configuration of the communication apparatus 100, and the hardware configuration of the communication apparatus 100 is not limited to the configuration illustrated in FIG. 27, and may be another configuration. .

Also, the processing procedure of the communication device 100 shown in the first and second embodiments can be regarded as a communication method.

100 communication device, 101 communication device, 102 communication device, 103 communication device, 104 communication device, 105 communication device, 106 communication device, 1001 frame reception unit, 1002 frame transmission unit, 1003 token frame determination unit, 1004 received data memory, 1005 Token frame generation unit, 1006 transmission data memory, 1007 reception WDT, 1008 own station number storage register, 1009 transfer destination station number storage register, 1010 transfer destination station number storage register before release, 1011 search frame generation unit, 1012 search frame determination unit, 1013 ACK frame generation unit, 1014 ACK frame determination unit, 1051 attended frame generation unit, 1052 attended frame determination unit, 1053 accept frame generation unit, 10 4 accept frame determination unit, 1055 transmission WDT.

Claims

A communication system including a plurality of communication devices each having a device number set therein, wherein token passing is performed between the plurality of communication devices,
Each communication device
Have a timer to keep time,
Receiving a token frame broadcast from another communication device and notifying the device number of the other communication device and the device number of the communication device to which the other communication device assigns a token;
Each time a token frame is received, the timer is reset, and the device number of the communication device that is the transmission source of the received token frame that is longer than the time required for the token to make a round among the plurality of communication devices Set a time-out time, which is a time proportional to the difference between the device number and the device number of the own device, to the timer, and start counting the timer,
Receiving a search frame broadcast-transmitted from a detected communication device that has detected that the communication device to which the token is transferred is not operating normally;
Among the plurality of communication devices,
A communication device in which a timeout due to the elapse of a timeout time has occurred after receiving the search frame,
As a response to the search frame, generate a number notification frame that notifies the device number of the communication device,
A communication system, wherein the generated number notification frame is transmitted to the detection communication device.
The communication system is:
Either ascending order or descending order of device numbers is designated as a token circulation order, and a token communication is performed between the plurality of communication devices according to the token circulation order,
Each communication device
A transfer destination device number storage that stores, as a token transfer destination device number, a device number next to the device number of its own device in the token circulation order among the device numbers of normal communication device groups operating normally in the communication system Part
Generating a token frame for notifying that the communication device in which the token transfer destination device number is set is a token transfer destination, and broadcasting the generated token frame;
When the token transfer destination communication device that is the token transfer destination is not operating normally, the token transfer destination communication device is excluded from the device numbers of the new normal communication device group excluding the token transfer destination communication device. Generate a search frame for requesting notification of the device number next to the device number, broadcast the generated search frame,
Among the device numbers of the new normal communication device group, the communication device that has been transmitted as a response to the search frame from a communication device in which a device number that is next to the device number of its own device in the token circulation order is set. Receive a number notification frame to notify the device number,
Write the device number notified in the number notification frame to the transfer destination device number storage unit as a new token transfer destination device number,
After the new token transfer destination device number is written in the transfer destination device number storage unit, a token for notifying that the communication device in which the new token transfer destination device number is set is the token transfer destination The communication system according to claim 1, wherein a frame is generated, and the generated token frame is broadcast.
A plurality of communication devices each including a device number are included, and either ascending order or descending order of device numbers is designated as a token circulation order, and token passing is performed between the plurality of communication devices according to the token circulation order. A communication system to be performed,
Each communication device
A transfer destination device number storage that stores, as a token transfer destination device number, a device number next to the device number of its own device in the token circulation order among the device numbers of normal communication device groups operating normally in the communication system Part
Generating a token frame for notifying that the communication device in which the token transfer destination device number is set is a token transfer destination, and broadcasting the generated token frame;
Receiving an attended frame that is broadcast from an unsubscribed communication device that is included in the communication system but has not subscribed to the token passing, in which the device number of the unsubscribed communication device is notified;
When the attended frame is received, it is determined whether the device number of the own device is the last in the token circulation order among the device numbers of the normal communication device group, and the device number of the own device is the last. If not, it is determined whether the device number of the unsubscribed communication device is a device number between the device number of the own device and the token transfer destination device number, and the device number of the unsubscribed communication device is When it is a device number between the device number of its own device and the token transfer destination device number, the device number of the unsubscribed communication device is written in the transfer destination device number storage unit as a new token transfer destination device number,
After the new token transfer destination device number is written in the transfer destination device number storage unit, a token for notifying that the communication device in which the new token transfer destination device number is set is the token transfer destination A communication system that generates a frame and broadcasts the generated token frame.
Each communication device
When the device number of the own device is the last in the token circulation order among the device numbers of the normal communication device group,
When the device number of the unsubscribed communication device is a device number that is later in the token circulation order than the device number of the own device, and the device number of the unsubscribed communication device is more than the token transfer destination device number The device number of the unsubscribed communication device is written in the transfer destination device number storage unit as a new token transfer destination device number in at least one of the case where the device number is the previous device number in the token circulation order, The communication system according to claim 3.
A communication device included in a communication system including a plurality of communication devices each having a device number set therein and performing token passing between the plurality of communication devices,
A timer unit for timing,
A token frame receiving unit that receives a token frame that is broadcast from another communication device and notifies the device number of the other communication device and the device number of the communication device to which the other communication device assigns a token;
Each time a token frame is received by the token frame receiving unit, the timer unit is reset, and the token frame receiving unit is longer than a time required for a token to make a round among the plurality of communication devices. A timer that sets a timeout time in the timer unit that is proportional to the number difference between the device number of the communication device that is the transmission source of the token frame received by the device and the device number of the own device, and starts the time measurement of the timer unit A control unit;
A search frame receiving unit that receives a search frame broadcast-transmitted from a detection communication device that has detected that the communication device to which the token is transferred is not operating normally;
After a search frame is received by the search frame receiving unit, when a time-out occurs due to the elapse of the time-out time in the timer unit, a number notification frame for notifying the device number of its own device as a response to the search frame A number notification frame generation unit to generate,
A communication apparatus, comprising: a number notification frame transmission unit that transmits the number notification frame generated by the number notification frame generation unit to the detection communication device.
The timer control unit
The shorter timeout time is set in the timer unit as a difference between a device number of a communication device that is a transmission source of the token frame received by the token frame receiving unit and a device number of the own device is smaller. 5. The communication device according to 5.
The communication device
Either ascending order or descending order of apparatus numbers is designated as a token circulation order, and included in a communication system in which token passing is performed between the plurality of communication apparatuses according to the token circulation order,
The search frame receiver
Receiving a search frame indicating a device number of the detection communication device;
The timer control unit
When a search frame is received by the search frame receiving unit, whether the device number of the detection communication device indicated in the search frame is the device number of the previous order in the token circulation order than the device number of the own device Judge whether it is the device number of the later order,
When the device number of the detection communication device is a device number in an order later than the device number of its own device, the timer unit is reset,
The device according to claim 1, wherein when the device number of the detection communication device is a device number in an order prior to the device number of its own device, the timer unit keeps timing without resetting the timer unit. The communication device according to 5 or 6.
The search frame receiver
When the detection communication device does not receive a number notification frame from any communication device in response to the search frame, the normal transmission that is broadcast from the detection communication device and operates normally in the communication system Receiving a tail notification frame for notifying that the device number of the detection communication device is the tail in the token circulation order among the device numbers of the communication device group;
The timer control unit
When the last notification frame is received by the search frame reception unit, the timer unit is reset, and a time corresponding to the device number of the own device is set in the timer unit as a response waiting time. Start timing,
The number notification frame generation unit includes:
When a timeout occurs due to the elapse of the response waiting time in the timer unit, a number notification frame for notifying the device number of the own device is generated as a response to the last notification frame,
The number notification frame transmission unit includes:
The communication device according to claim 7, wherein a number notification frame for the tail notification frame generated by the number notification frame generation unit is transmitted to the detection communication device.
The timer control unit
9. The communication apparatus according to claim 8, wherein a shorter response waiting time is set in the timer unit as the apparatus number of the own apparatus is closer to the first apparatus number in the token circulation order.
A plurality of communication devices each including a device number are included, and either ascending order or descending order of device numbers is designated as a token circulation order, and token passing is performed between the plurality of communication devices according to the token circulation order. A communication device included in a communication system to be performed,
A transfer destination device number storage that stores, as a token transfer destination device number, a device number next to the device number of its own device in the token circulation order among the device numbers of normal communication device groups operating normally in the communication system And
A token frame generation unit that generates a token frame for notifying that the communication device in which the token transfer destination device number is set is a token transfer destination;
A token frame transmission unit for broadcasting the token frame generated by the token frame generation unit;
When the token transfer destination communication device that is the token transfer destination is not operating normally, the token transfer destination communication device is excluded from the device numbers of the new normal communication device group excluding the token transfer destination communication device. A search frame generator for generating a search frame for requesting notification of a device number corresponding to the device number;
A search frame transmission unit that broadcasts a search frame generated by the search frame generation unit;
Among the device numbers of the new normal communication device group, the communication device that has been transmitted as a response to the search frame from a communication device in which a device number that is next to the device number of its own device in the token circulation order is set. A number notification frame receiving unit for receiving a number notification frame for notifying a device number;
A transfer destination device number update unit that writes the device number notified in the number notification frame as a new token transfer destination device number in the transfer destination device number storage unit;
The token frame generation unit
After the new token transfer destination device number is written in the transfer destination device number storage unit by the transfer destination device number update unit, the communication device to which the new token transfer destination device number is set transfers tokens. A communication apparatus that generates a token frame notifying that it is ahead.
The search frame generator is
When the number notification frame receiving unit does not receive a number notification frame from any communication device, the device number of the own device is the last in the token circulation order among the device numbers of the new normal communication device group. Judging
Generating a tail notification frame for notifying that the device number of the own device is the tail in the token circulation order among the device numbers of the new normal communication device group;
The search frame transmission unit
Broadcast transmission of the last notification frame generated by the search frame generation unit,
The number notification frame receiving unit,
The device number of the communication device transmitted as a response to the last notification frame is notified from the communication device in which the device number corresponding to the head in the token circulation order is set among the device numbers of the new normal communication device group Receive the number notification frame to
The transfer destination device number update unit,
11. The communication apparatus according to claim 10, wherein the apparatus number notified in the number notification frame for the last notification frame is written in the transfer destination apparatus number storage unit as a new token transfer destination apparatus number.
The communication device further includes:
A token frame receiving unit that receives a token frame that is broadcast from another communication device and notifies the device number of the other communication device and the device number of the communication device to which the other communication device assigns a token;
A timer unit for timing,
Each time a token frame is received by the token frame receiving unit, the timer unit is reset, and the token frame receiving unit is longer than a time required for a token to make a round among the plurality of communication devices. A timer that sets a timeout time in the timer unit that is proportional to the number difference between the device number of the communication device that is the transmission source of the token frame received by the device and the device number of the own device, and starts the time measurement of the timer unit A control unit,
The search frame generator is
11. The search frame is generated by detecting that the token transfer destination communication apparatus is not operating normally when the timeout occurs after the timeout period elapses in the timer unit. Or the communication apparatus of 11.
The timer control unit
The shorter timeout time is set in the timer unit as a difference between a device number of a communication device that is a transmission source of the token frame received by the token frame receiving unit and a device number of the own device is smaller. 12. The communication device according to 12.
A plurality of communication devices each including a device number are included, and either ascending order or descending order of device numbers is designated as a token circulation order, and token passing is performed between the plurality of communication devices according to the token circulation order. A communication device included in a communication system to be performed,
A transfer destination device number storage that stores, as a token transfer destination device number, a device number next to the device number of its own device in the token circulation order among the device numbers of normal communication device groups operating normally in the communication system And
A token frame generation unit that generates a token frame for notifying that the communication device in which the token transfer destination device number is set is a token transfer destination;
A token frame transmission unit for broadcasting the token frame generated by the token frame generation unit;
An attended frame reception unit that receives an attended frame that is broadcast from a non-participating communication device that is included in the communication system but has not subscribed to the token passing and that is notified of a device number of the unsubscribed communication device;
When an attended frame is received by the attended frame receiving unit, it is determined whether the device number of the own device is the last in the token circulation order among the device numbers of the normal communication device group, and If the device number is not at the end, it is determined whether the device number of the unsubscribed communication device is a device number between the device number of the own device and the token transfer destination device number, and When the device number of the communication device is a device number between the device number of the own device and the token transfer destination device number, the transfer destination device is set with the device number of the unsubscribed communication device as a new token transfer destination device number. A transfer destination device number update unit for writing to the number storage unit,
The token frame generation unit
After the new token transfer destination device number is written in the transfer destination device number storage unit by the transfer destination device number update unit, the communication device to which the new token transfer destination device number is set transfers tokens. A communication apparatus that generates a token frame notifying that it is ahead.
The transfer destination device number update unit,
When the device number of the own device is the last in the token circulation order among the device numbers of the normal communication device group,
When the device number of the non-participating communication device is a device number subsequent to the device number of the own device in the token circulation order, and the device number of the unsubscribed communication device is more than the token transfer destination device number The device number of the unsubscribed communication device is written in the transfer destination device number storage unit as a new token transfer destination device number in at least one of the case where the device number is the previous device number in the token circulation order, The communication device according to claim 14.
The communication device further includes:
When the transfer destination device number update unit writes the device number of the unsubscribed communication device as a new token transfer destination device number in the transfer destination device number storage unit, the unsubscribed communication device joins the token passing. An accept frame generation unit for generating an accept frame for notifying that the
The communication device according to claim 14, further comprising an accept frame transmission unit configured to transmit the accept frame generated by the accept frame generation unit to the non-participating communication device.