JP3587092B2 - Response distributed communication method and communication system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a response distributed communication method applicable to a disaster prevention system and the like, and a communication system for the communication system in which a plurality of nodes mutually transmit and receive data.
[0002]
[Prior art]
Conventionally, various communication methods have been proposed and adopted. For example, Japanese Patent Application Laid-Open No. 5-215033 discloses a broadcast request transmitted from a calling station having a plurality of stations connected to a network. In a broadcast communication system in which a plurality of receiving stations that have received information transmit broadcast response information to the calling station, each receiving station receives a broadcast response after a delay time different from that of the other called stations has elapsed. A broadcast system is described that transmits information and thereby suppresses an increase in local traffic on the network.
[0003]
In Japanese Patent Laid-Open No. 10-79753, a broadcast message transmitting station includes delay type information for specifying a waiting time until a broadcast message receiving station transmits a response message. The broadcast message receiving station receives the broadcast message, reads the delay type information in the message, sets its own delay time, and sets the delay A broadcast communication control method is disclosed in which a response message is transmitted after a lapse of time, whereby the timing at which the response message is returned with a short broadcast message can be controlled.
[0004]
[Problems to be solved by the invention]
However, the methods described in the above publications only specify the operation when a single node broadcasts, and these methods are applied to a communication system in which a plurality of nodes mutually transmit and receive data. Can not do it.
[0005]
By the way, such a communication system has a problem that data is lost when a plurality of nodes perform transmission.
[0006]
FIG. 10 is an explanatory diagram of this problem. In the example of this figure, when one node transmits a request at time t1, and another node transmits a request at time t2, in the section TM1 after that time t2, Since double traffic occurs when a single node transmits a request, data may be lost due to data collision or reception buffer leakage. If the number of nodes that transmit requests further increases, the amount of traffic further increases, so the risk of data loss increases further. In particular, in a distributed system in which each node operates autonomously and transmits data asynchronously, it is difficult to predict the transmission timing of other nodes, and as a result, all nodes transmit requests simultaneously. It is necessary to design a communication system assuming the above. However, in FIG. 10, the transmission signals other than the time points t1 and t2 are response transmission signals.
[0007]
In a communication system in which a plurality of nodes exchange data with each other, a communication method that minimizes request delay is also desired. A communication method that minimizes response delay is also desired. In the latter case, if each node has a parallel processing function, the next request can be transmitted before the collection of responses to a request is completed. Therefore, a more complicated transaction management function is required, and the design of each node, and hence the communication system, is complicated. For this reason, the design without the parallel processing function becomes extremely easy, and in this case, it is required to minimize the response delay.
[0008]
The present invention has been made in view of the above circumstances, and congestion of a communication system such as when traffic exceeding the communication capacity or data reception capacity of a transmission medium occurs due to transmission of requests by a plurality of nodes. An object is to provide a response distributed communication method that can be avoided.
[0009]
[Means for Solving the Problems]
To solve the above problemsofThe response distributed communication method according to claim 1 is a communication system in which a plurality of nodes mutually transmit and receive data.In each of the plurality of nodesA communication method for distributing responses, wherein each of the plurality of nodes includes:With a timerWhen holding a unique value assigned and sending a responseAs a step of starting the timer;Depending on the specific valueA step of delaying the transmission timing and a step of transmitting the response in a predetermined frame at the transmission timing, and transmitting a response to a request transmitted by another node while collecting a response of a certain node. As a step, after the timer started at the time of transmitting a request corresponding to a response of the certain node, a step of delaying transmission timing according to the specific value, and a request transmitted by the other node at the transmission timing And transmitting the response in a predetermined frame.
According to this method, since the transmission timing of the response of each node is delayed according to a unique value, the congestion of the communication system such as when the traffic exceeding the communication capacity or the data reception capability of the transmission medium occurs is generated. Can be avoidedThe
[0010]
The response distribution type communication method according to claim 2 is a communication method for distributing responses of each of the plurality of nodes in a communication system in which a plurality of nodes mutually transmit and receive data. Each of which holds and pre-stores a unique value assigned and a list of nodes that are expected to return a response, each having a timer, and starting the timer as a step when sending a request; Including the step of including in the header information the designation information of at least one destination node to which the request should be transmitted using, and the step of transmitting the request in a predetermined frame together with the header information. If the request is received in a predetermined frame, whether the header information in the predetermined frame is addressed to itself A step of delaying the transmission timing according to the specific value and a step of transmitting the response in a predetermined frame at the transmission timing. When the request is retransmitted, if a response is received from all of the nodes expected to return the response included in the header information of the request before a timeout occurs due to the timing of the timer, A step of stopping the timer, and before receiving a response from all of the nodes that expect the response to be returned, if a time-out occurs due to timing of the timer, a response is sent out of the nodes that expect the response to be returned. Resending the request only to a node that has not been returned. If a response is not returned from the retransmission partner even if the request is retransmitted a predetermined number of times in the step of performing the step, the node of the partner is treated as a faulty node, and the request is retransmitted A step of making the number of retransmissions for the failed node less than the number of retransmissions for a node not treated as the failed node.
According to this method, since the transmission timing of the response of each node is delayed according to a unique value, the congestion of the communication system such as when the traffic exceeding the communication capacity or the data reception capability of the transmission medium occurs is generated. It can be avoided.In addition to sending a response if the data is addressed to itself, the request is retransmitted only to the nodes that do not return the response among the nodes that expect the response to be returned, thus suppressing redundant traffic. In addition, it is possible to reduce the probability of request data loss due to signal collision or overflow of the reception buffer. Furthermore, since the number of retransmissions to the failed node is reduced, the next request can be transmitted immediately. That is, the next request can be transmitted promptly by reducing the redundant waiting time due to repeated retransmissions to nodes that cannot expect a response.
[0011]
ContractClaim3Response distributed communication method according to the present inventionIs a communication method for distributing responses of each of the plurality of nodes in a communication system in which a plurality of nodes mutually transmit and receive data,Each of the plurality of nodes isIn addition to holding the assigned unique value, as a transmission function, when transmitting a response in a predetermined frame, a response transmission function for delaying the transmission timing of the response according to the specific value, and transmitting the request in a predetermined frame A request transmission function that individually transmits the request without delaying the transmission timing, and at least one of the plurality of nodes has more requests for data transmission than other nodes. The node is set as a high priority node, and the communication system is set so that a response from the high priority node is transmitted before a response from the other node. When no response is returned from the priority node, the collection of responses is interrupted and the request is retransmitted to the high priority node.
According to this method,Since the response transmission timing of each node is delayed according to a specific value, congestion of the communication system such as when traffic exceeding the communication capacity or data reception capability of the transmission medium occurs can be avoided. Further, since the request transmission timing is not delayed, the request can be transmitted promptly. In addition, requests for high priority nodes are given priority, minimizing request delays for high priority nodes.Can be suppressed.
[0012]
ContractClaim4Response distributed communication method according to the present inventionIs a communication method for distributing responses of each of the plurality of nodes in a communication system in which a plurality of nodes mutually transmit and receive data,Each of the plurality of nodes isIt has a communication event cycle timer and a response reception completion waiting timer, and has a node number as a unique value assigned, and a connection list that lists node numbers of the node and node numbers of other nodes, and sets As a step, the node number of the own node and the node number in the connection list are compared, the transmission order of the response of the own node is calculated, and the communication is performed according to the number of nodes connected to the communication system. A step of setting each time measured by an event cycle timer and a response reception completion waiting timer, and as a step of transmitting a response, the transmission medium of the response is determined from the transmission speed of the transmission medium and the data length of the response. To calculate the stay time in the network and to avoid communication system congestion from the stay time Calculating a transmission time interval of a main response, characterized by a step of transmitting the response at a given frame according to the transmission order and the transmission time interval.
According to this method,Since the response transmission timing of each node is delayed according to a specific value, congestion of the communication system such as when traffic exceeding the communication capacity or data reception capability of the transmission medium occurs can be avoided. In addition, since the response transmission time interval is calculated based on the transmission speed of the transmission medium and the response data length, the response can be returned with a minimum delay. In addition, congestion of the communication system can be avoided even if the number of nodes connected to the communication system changes, and response delays can be minimized according to the number of nodes connected to the communication system.The
[0013]
The invention according to claim 5Claim4In the response distributed communication method described above, each of the plurality of nodes includes:If the number of faulty nodes increases, the time length of each time measured by the communication event cycle timer and the response reception completion waiting timer is made shorter than before the number of faulty nodes increases.
According to this method,Redundant delay due to waiting for a response from the failed node can be suppressed and response delay can be minimized.The
[0014]
The invention described in claim 6Claim 1To any of 4In the response distributed communication method described,Predetermined frameThe load of the communication system is calculated from the reception time, and it is determined whether or not the load of the communication system has increased from this load. If the load of the communication system has increased, the transmission time interval of the response is set. LengthenIt is characterized by that.
According to this method, if the load on the communication system increases, the response transmission time interval becomes longer. Therefore, the probability of data loss due to signal collision or reception buffer overflow can be kept low.
[0015]
A communication system according to a seventh aspect of the present invention is the response distributed communication method according to any one of the first to sixth aspects, wherein a plurality of nodes mutually transmit and receive data.
According to this system, since the response transmission timing of each node is delayed according to a unique value, the congestion of the communication system such as when traffic exceeding the communication capacity or data reception capability of the transmission medium occurs is generated. It can be avoided.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is an explanatory diagram of a response distributed communication method according to the first embodiment of the present invention. The first embodiment will be described below with reference to FIG.
[0023]
First, a communication system to which the response distributed communication method according to the first embodiment is applied will be described together with an embodiment according to the communication system of the present invention.
[0024]
FIG. 2 is a diagram showing a configuration example of the communication system, FIG. 3 is a diagram showing a frame format example of data transmitted / received in the communication system, and the communication system 1 shown in FIG. And a plurality (8 in the example of FIG. 2) of nodes 3 connected to the network 2. However, the numbers in parentheses “[]” shown in FIG. 2 indicate node numbers (the same applies to FIG. 1).
[0025]
A frame F of data transmitted and received in the communication system 1 includes a header part F1 and a data part F2. The header part F1 includes a transmission source node number F11, a transmission destination node / group number F12, a transmission destination partner designation F13, A request / response message type F14 and a transaction number F15 are included.
[0026]
4 is a hardware configuration diagram of each node shown in FIG. 2, FIG. 5 is a functional block diagram provided on the hardware shown in FIG. 4, particularly on the control unit, and each node 3 is as shown in FIG. A reception unit connected to the network 2 and having a transmission unit 30 for transmitting data to the network 2 and a reception buffer memory (reception buffer) 31a, connected to the network 2 and receiving data from the network 2 Unit 31, timer 32 for timing, memory 33 for storing various data, these transmitting unit 30, receiving unit 31, timer 32 and memory 33, etc. are connected, and various controls for the node 3 etc. It is comprised by the control part (CPU) 34 which performs a process.
[0027]
On the hardware configured in this way, the processing function of the control unit 34 that operates according to a predetermined soft program, as shown in FIG. 5, the driver 300 for the transmission unit 30 and the reception unit 31, and the data unit F2 For example, an application task unit 301 that performs information processing and the like, and a communication protocol layer unit 302 that processes a frame F to be transmitted and received based on information in the header part F1.
[0028]
In this communication protocol layer unit 302, as a function of performing various management, a frame reception history management unit 303 that manages a frame reception history in response to a notification from a header analysis unit 316 described later and notifies the application task unit 301 of the frame. A system state management unit 304, a response management unit 305 that manages responses to frame transmission, and a transaction management unit 306 that specifies the transaction number of the header portion F1. In addition to a queue 307 for notifying the application task unit 301 of information from the response management unit 305 and the transaction management unit 306, an event flag queue 308 is also provided.
[0029]
Further, the communication protocol layer 302 includes a request input queue 309 to be transmitted from the application task unit 301 and a transaction number specified by the transaction management unit 306 according to the format shown in FIG. Is included in the header part F1 and information of the request obtained from the queue 309 is included in the data part F2 to assemble the frame F, and the response manager 305 is notified of the node number of at least one node designated as the transmission destination. A request frame creation unit 310 that registers a request event in 308 and a queue 311 that captures frames obtained from the request frame creation unit 310 for transmission are provided. In addition, the communication protocol layer unit 302 includes a response frame creation unit 312 that assembles a response frame F and a queue 313 that captures frames obtained from the response frame creation unit 312 for transmission as response transmission functions. ing. The queues 311 and 313 have a transmission delay unit 314a in the subsequent stage, and immediately pass the frame from the queue 311 to the driver 300, while passing the frame from the queue 313 through the transmission delay unit 314a to delay the transmission timing. Then, a frame transmission unit 314 that is passed to the driver 300 is created.
[0030]
Further, the communication protocol layer unit 302 includes a queue 315 for frame input received from the driver 300, and a header analysis unit 316 that analyzes the header part F1 in a frame obtained from the queue 315. .
[0031]
The processing function of the header analysis unit 316 will be described in more detail. For example, referring to the transmission destination node / group number F12 in the header part F1, if it is not addressed to itself, the frame having the header part F1 is discarded. Processing is performed.
[0032]
If it is a request with reference to the message type F14 in the header part F1, the destination partner designation F13 is further referred to, and if it is not addressed to itself, processing for discarding the frame is performed. On the other hand, when it is addressed to itself, a process of passing the frame or its header part F1 to the response frame creation part 312 is performed. As a result, a response frame is created by the response frame creation unit 312 and is queued in the queue 313, and then passed to the driver 300 through the frame transmission unit 314. In addition, a response event is registered in the queue 308 and a process of notifying the transaction management unit 306 of the received frame is performed. At this time, if the transaction management unit 306 determines that the reception is not double, a request message is notified to the application task unit 301 via the queue 307.
[0033]
On the other hand, if the message type F14 is referred to and it is a response, processing for notifying the response management unit 305 of the information of the header portion F1 is performed. In this case, the response management unit 305 performs a process of stopping the response reception completion waiting timer and notifying the application task 301 of the normal end when all responses are returned from all the nodes that should obtain the response. .
[0034]
Here, the timer 32 shown in FIG. 4 is used as a communication event cycle timer, a response reception completion waiting timer, and a response transmission waiting timer.
[0035]
The communication event cycle timer is queued when an event does not exist in the event flag queue 308, when a request is transmitted, or when a request is received regardless of whether the event is addressed, or when the timing of the communication event cycle timer ends. If at least one event is queued at 308, it is activated and has no stop condition. Also, processing that refers to the queue 308 is executed at time-out.
[0036]
The response reception completion waiting timer is started if a request is transmitted when there is no event in the queue 308, or if an event obtained from the queue 308 after the end of the timing of the communication event cycle timer is a request, and then When all responses are received from all nodes to be returned, the response management unit 305 stops the responses. Also, at the time of timeout, if the number of retransmissions is not reached, a node that has not returned a response is set in the destination partner designation F13 of the header part F1 and retransmitted. When retransmission is performed for the number of retransmissions, the response management unit 305 performs processing to notify the system state management unit 304 of the node number of the node that has not returned a response and to notify the application task unit 301 as abnormal termination. .
[0037]
The response transmission waiting timer is activated and has a stop condition if a request is transmitted when there is no event in the queue 308, or an event obtained from the queue 308 after the end of the time measurement of the communication event cycle timer is a response. No. Further, at the time of timeout, processing for transmitting a response is performed.
[0038]
Next, the response distributed communication method according to the first embodiment applied to the communication system 1 having the above-described configuration will be described. When a number is allocated and held, and a response is transmitted from the frame transmission unit 314, a method of delaying the transmission timing of the response by the transmission delay unit 314a according to the unique value is employed. The delay time is set to a value obtained by node number × 10 ms. This delay process is performed by the transmission delay unit 314a shown in FIG.
[0039]
An operation example by the above method will be described with reference to FIG. However, the transmission delay time in the transmission medium and the data processing time in the driver 300 are sufficiently short and can be ignored.
[0040]
When the node 3 [2] transmits a request to the other nodes 3 [1], 3 [3] to 3 [8], for example, by group communication or multicast (t10), each of the other nodes has a node number × 10 ms. Responses are returned sequentially after the delay time of the obtained value. That is, a response from the node 3 [1] is received at a time t11 after a delay of about 10 ms, and a response from the node 3 [3] is subsequently received at a time t13 after a delay of about 30 ms, and finally the node 3 [8 ] Is received at time t18 after approximately 80 ms delay. In this way, since the response transmission time of each node is uniquely determined in the communication event cycle, traffic exceeding the communication capacity or data reception capability of the transmission medium occurs due to the transmission of requests by a plurality of nodes. It becomes possible to avoid congestion of the communication system. However, it is assumed that the nodes 3 [1] to 3 [8] belong to the same group.
[0041]
Further, as shown in FIG. 1, if the node 3 [3] transmits a request to, for example, all other nodes at a time t123 between the time t12 and the time t13, the other nodes are based on the time t123. Since the responses are sequentially returned from each of them, the loss of the signal due to the collision can be prevented, and the congestion of the communication system can be avoided as described above.
[0042]
FIG. 6 is an explanatory diagram of a response distributed communication method according to the second embodiment of the present invention. The second embodiment will be described below with reference to this diagram. This response distributed communication method is also applied to the communication system 1 as in the first embodiment. In the second embodiment, when a request is transmitted to each of the plurality of nodes 3, the designation information of at least one destination node to which the request is to be transmitted is included in the destination partner designation F13 of the header part F1. When the request (data portion F2) is transmitted as data together with the header portion F1 and the data is received, whether the received data is the data addressed to itself based on the information of the header portion F1 obtained from this data If the data is addressed to itself, a response is transmitted.
[0043]
An operation example according to the above method will be described with reference to FIG. If the node 3 [2] transmits a request to, for example, the nodes 3 [1] and 3 [8] (t20), the data received from the node 3 [2] is received at the nodes 3 [1] and 3 [8]. Since the data is addressed to itself, a process of transmitting a response is performed at time t21 after a delay of approximately 10 ms and time t28 after a delay of approximately 80 ms, and each of the nodes 3 [3] to 3 [7] Since the data received from the node 3 [2] is not the data addressed to itself, the process for transmitting the response is not executed. Thus, the node 3 [2] receives a response from the node 3 [1] at the time t21 and receives a response from the node 3 [8] at the time t28. In this way, by eliminating responses from nodes that do not need to send requests, redundant traffic can be suppressed, and the probability of loss of request data due to signal collision or overflow of the reception buffer is kept low. Can do.
[0044]
As shown in FIG. 6, if the node 3 [3] transmits a request to, for example, the nodes 3 [1] and 3 [2] at the time t223 between the time t22 and the time t23, the time t223 is set. Since the responses are sequentially returned only from the nodes 3 [1] and 3 [2] based on the reference, it is possible to prevent the loss of the signal due to the collision.
[0045]
In the first and second embodiments, as an operation example, when the node 3 [3] transmits a request while collecting the response of the node 3 [2], the collection of the response to the node 3 [3] is performed by the node 3 [3]. 2] is performed in parallel with the collection of responses. However, the present invention is not limited to this, and the collection of responses to node 3 [3] may be started after the collection of responses of node 3 [2] is completed. Good. In this case, when the communication event period timer started at the time of transmitting the request of the node 3 [2] ends, a response to the node 3 [3] is started, and thereafter, the response is sequentially returned according to the node number × 10 ms. do it. An example of the operation in this case is shown in FIG. In FIG. 7, when the node 3 [2] transmits a request to, for example, all other nodes (t300), responses are sequentially returned from each of the other nodes 3 [1], 3 [3] to 3 [8]. Come (t301, t303,..., T308). Thereafter, when the communication event cycle timer started at the time of request transmission of the node 3 [2] ends (t309), the other nodes 3 [1], 3 [2], 3 [4] with respect to the node 3 [3]. ] To 3 [8], responses are sequentially returned (t310, t311,..., T317). Thereby, it becomes possible to avoid congestion of the communication system.
[0046]
Next, a response distributed communication method according to the third embodiment of the present invention will be described. This response distributed communication method is also applied to the communication system 1 as in the first embodiment. In the first and second embodiments, the response transmission time interval is a constant value of 10 ms, but in the third embodiment, a method of setting the response transmission time interval to a value adapted to the communication system 1 is adopted. It is done. That is, when a response is transmitted to each of the plurality of nodes 3, the stay time in the transmission medium of the response is calculated from the transmission speed of the transmission medium and the data length of the response frame, and the communication system is calculated from the stay time. The transmission time interval of the response necessary for avoiding the congestion of 1 is calculated, the transmission order of the response is determined from the unique value held by the node 3, and the response is sent according to the transmission order and the transmission time interval. The method of sending is taken.
[0047]
An example of calculating a response transmission time interval by this method will be described. For example, if the transmission rate of the transmission medium is 80 kBaud and the average data length of the request and response frames transmitted by each node 3 is 200 bytes, the response time 2.5 ms (= 200 bytes / 80 kbps) is calculated as the stay time in the transmission medium. Subsequently, the transmission time interval is calculated by adding a predetermined value (≧ 0) or multiplying the stay time by a predetermined value (≧ 1). For example, if the predetermined value is zero, the response transmission time interval is 2.5 ms. As a result, it is possible to avoid congestion of the communication system and return a response with a minimum delay.
[0048]
Next, a response distributed communication method according to the fourth embodiment of the present invention will be described. This response distributed communication method is also applied to the communication system 1 as in the first embodiment. In the fourth embodiment, the load of the communication system 1 is calculated from the data reception time, it is determined whether or not the load of the communication system 1 has increased from this load, and if the load of the communication system 1 has increased. A method of extending the response transmission time is employed.
[0049]
As a specific example, among the plurality of nodes 3 in the communication system 1, the node 3 serving as a master for determining the response transmission time is selected. In FIG. 2, for example, assuming that node 3 [1] is a master, when data is received from driver 300 for node 3 [1], the frame reception history is received from header analysis unit 316 regardless of whether it is addressed to the node 3 [1]. The management unit 303 is notified of the reception event (see FIG. 5), and the response transmission time interval (for example, 2.5 ms) is calculated in the same manner as in the third embodiment.
[0050]
Here, for example, if the monitoring result of the load state of the communication system 1 is verified every second, it is determined whether or not the load of the communication system 1 is increased by 400 frames (= 1 s / 2.5 ms). Can be obtained as a reference value. Although a value obtained by adding a predetermined value to 400 may be used, here, for simplicity, 400 is used as a reference value as it is.
[0051]
In this case, the node 3 [1] is caused to calculate, as the load of the communication system 1, the number of frames received from the data reception time in one second every second, and the calculated number of frames is equal to or more than the reference value 400. If it is, it is determined that the load on the communication system 1 is increasing, while if it is less than 400, it is determined that the load on the communication system 1 is not increasing. Furthermore, when it is determined that the load on the communication system 1 is increasing for the node 3 [1], all of the other nodes are notified so as to temporarily increase the transmission time interval of the response to 5ms, Thereafter, if it is determined that the load on the communication system 1 has not increased, all of the other nodes are notified so that the response transmission time interval is returned to 2.5 ms. On the other hand, the transmission time interval is changed to 5 ms or 2.5 ms in response to the notification from the node 3 [1] for all other nodes that receive these notifications.
[0052]
According to this specific example, if the load on the communication system 1 increases, the response transmission time becomes longer, so that the probability of loss of request data due to signal collision or reception buffer overflow can be kept low.
[0053]
FIG. 8 is an explanatory diagram of a response distributed communication method according to the fifth embodiment of the present invention. The fifth embodiment will be described below with reference to FIG. This response distributed communication method is also applied to the communication system 1 as in the first embodiment. In the fifth embodiment, for each of a plurality of nodes 3, a list of nodes 3 that are expected to return responses is stored in advance, and when a request is transmitted, a response reception completion waiting timer is started and the list is used. Then, the designation information of at least one destination node to which the request is to be transmitted is included in the header part F1, the request is transmitted together with the header part F1, and thereafter, before a timeout occurs due to the timing of the response reception completion waiting timer In addition, when responses are received from all of the nodes that are expected to return responses included in the header part F1, the response reception completion waiting timer is stopped, while responses are received from all of the nodes that are expected to return responses. If a timeout occurs before the response reception completion waiting timer counts, the node that has not returned a response among the nodes that expect the response to be returned How to perform a retransmission of the request is taken only for.
[0054]
Next, an operation example by the above method will be described. When the node 3 [2] transmits a request to, for example, all other nodes (t400), responses are sequentially returned from each of the other nodes. In the example of FIG. 8, however, the node 3 [3] ], No response is returned, and responses are sequentially returned from each of the other nodes 3 [1], 3 [4] to 3 [8] except for the node 3 [3] (t401,..., T408). ).
[0055]
In this case, before receiving a response from all the nodes that expect the response to be returned, a timeout occurs due to the timing of the response reception completion waiting timer (t409), and at this point, node 3 [2] designates the destination partner. The request is retransmitted with only F3 at node 3 [3]. At this time, the destination node / group number F12 and the transaction number F15 are not changed. Thereafter, a response is returned from the node 3 [3] to the node 3 [2] at time t412 after 30 ms has elapsed.
[0056]
In this way, by resending only to a node that has not transmitted a response, a response from a node that does not need to be retransmitted is eliminated, so that it becomes possible to suppress redundant traffic, and The probability of loss of request data due to a collision or overflow of the reception buffer can be kept low. In addition, when the request is received normally and the response to the request is lost due to a signal collision, if the request is retransmitted with different destination node / group number F12 and transaction number F15, double reception occurs and the application runs out of control. However, if retransmission is performed without changing the destination node / group number F12 and the transaction number F15, communication without such danger becomes possible.
[0057]
In the fifth embodiment, if each of the plurality of nodes 3 does not receive a response from the retransmission partner even if the request is retransmitted a predetermined number of times, the partner node is designated as the failed node. Then, the number of retransmissions for the failed node may be made smaller than the number of retransmissions for the node not treated as a failed node. For example, if the predetermined number of times is set to 3 and the number of retransmissions for the failed node is set to 1, the node 3 [2] retransmits 3 times to the node 3 [3] as in the operation of FIG. If no response is returned from the node 3 [3] even after performing the above, the response management unit 305 notifies the system state management unit 304 that the node 3 [3] is a failed node in the node 3 [2]. Then, the process of setting the number of retransmissions for the subsequent node 3 [3] to 1 is performed. Subsequently, a process for notifying the application task unit 301 of the abnormal end is performed, thereby completing the communication process. Thereafter, if the node 3 [2] transmits a request to the node 3 [3] and a response to the request is not returned, the node 3 [3] is retransmitted only once. Thereafter, if there is no response to the retransmission, the communication process is completed. As a result, a redundant waiting time due to repeated retransmissions to nodes that cannot expect a response can be shortened, and the next transmission can be quickly performed for the shortened time.
[0058]
FIG. 9 is an explanatory diagram of a response distributed communication method according to the sixth embodiment of the present invention. The sixth embodiment will be described below with reference to this diagram. This response distributed communication method is also applied to the communication system 1 as in the first embodiment. In the sixth embodiment, among the plurality of nodes 3, at least one node that has more requests for data transmission than other nodes is set as a high priority node, and a response from the high priority node is the other node. If the communication system 1 is set to be transmitted before the response from the node, and no response is returned from the high priority node to the other nodes, the collection of the response is interrupted and the high priority is A method is adopted in which the request is retransmitted to the node.
[0059]
Next, an operation example by the above method will be described. However, in FIG. 9, it is assumed that node 3 [1] has more requests for data transmission than other nodes and is set as a high priority node.
[0060]
When the node 3 [2] transmits a request to all other nodes, for example (t50), the response from the node 3 [1] set as the high priority node is transmitted from the other nodes 3 [3] to 3 [8]. In the example of FIG. 9, the response is received from the node 3 [1] set as the high priority node for some reason. Not returned at time t51 to be done. In this case, the node 3 [2] interrupts the collection of the response, and retransmits the request to the node 3 [1] until, for example, a response is to be returned from the next node 3 [3]. The same request is retransmitted to the other nodes 3 [3] to 3 [8] (time t52). At this time, the destination node / group number F12 and the transaction number F15 are not changed. This makes it possible to prevent an application runaway due to double reception.
[0061]
Thereafter, in the example of FIG. 9, the response from the node 3 [1] set as the high priority node is returned before the responses from the other nodes 3 [3] to 3 [8]. Responses are returned in sequence (t53, t55 to t60). Thereby, the delay of the response from the high priority node can be minimized.
[0062]
Next, a response distributed communication method according to the seventh embodiment of the present invention will be described. This response distributed communication method is also applied to the communication system 1 as in the first embodiment. In the seventh embodiment, for each of the plurality of nodes 3, the length of each time measured by the communication event cycle timer and the response reception completion waiting timer is set according to the number of nodes connected to the communication system 1. A method is adopted in which the value is set to a value that can avoid congestion.
[0063]
Specifically, at the time of initial setting, each node 3 so that the application task unit 301 notifies the communication protocol layer unit 302 of the node number of the own node, the number of nodes of the communication system 1 and a list of node numbers (connection list). Set. Also, each node 3 is set so that the node number of the own node is compared with the node number in the connection list, and the response transmission order of the own node is calculated.
[0064]
For example, the node number of the own node is9If the node numbers in the connection list are 1, 3, 4, 6, 9, 10, 13, 16, and 19, the response transmission order of the own node is next to 1, 3, 4, and 6. It will be fifth from there. Thus, node number and response transmission orderIsNot necessarily matchYes. AndIn the seventh embodiment, the length of each time measured by the communication event cycle timer and the response reception completion waiting timer is adaptively set according to the number of nodes connected to the communication system 1.TheIn this case, since the number of nodes is 10 and the number of nodes is increased by 2 with respect to the number of nodes of 8 in FIG. The length is changed to 1.25 (= 10/8) times that when the number of nodes is 8.more thanThus, the response delay time can be set to the minimum according to the number of nodes connected to the communication system.
[0065]
In the seventh embodiment, when the above-described failure mode is detected, the number of detected failure nodes may be added to the setting of the length of each timed time. That is, according to the number of nodes connected to the communication system 1 and the number of failed nodes, the length of each time measured by the communication event period timer and the response reception completion waiting timer is set to a value that can avoid congestion of the communication system 1. You may make it do. For example, when the number of nodes connected to the communication system 1 is 10 and the number of failed nodes is 1, the length of each time measured by the communication event period timer and the response reception completion waiting timer is set to 10 when the number of nodes is 10. What is necessary is just to change to 0.9 times. Note that the node number of the local node is9When the node number in the connection list is 1, 3, 4, 6, 9, 10, 13, 16, 19 and the node number of the failed node is 13, the response transmission order of the own node is fifth. If the node number of the failed node is 4, the response transmission order of the own node changes to the fourth, so that the delay time obtained by the node number × 10 ms changes.
[0066]
【The invention's effect】
As is clear from the above, according to the first aspect of the invention,, LegendIt is possible to avoid congestion of the communication system such as when traffic exceeding the communication capacity or data reception capability of the transmission medium occurs.
[0067]
According to invention of Claim 2,It is possible to avoid congestion of the communication system such as when traffic exceeding the communication capacity or data reception capability of the transmission medium occurs. Also,Redundant traffic can be suppressed, and the probability of request data loss due to signal collision or overflow of the reception buffer can be kept low.. In addition, the next request can be sent immediately..
[0068]
According to invention of Claim 3,It is possible to avoid congestion of the communication system such as when traffic exceeding the communication capacity or data reception capability of the transmission medium occurs. Also,Enables quick transmission of requests. In addition, request delays for high priority nodes can be minimized..
[0069]
According to invention of Claim 4,It is possible to avoid congestion of the communication system such as when traffic exceeding the communication capacity or data reception capability of the transmission medium occurs. Also,Allows responses to be sent back with minimal delay. Furthermore, congestion of the communication system can be avoided even if the number of nodes connected to the communication system changes, and response delay can be minimized according to the number of nodes connected to the communication system..
[0070]
According to invention of Claim 5,Suppresses redundant delays due to waiting for responses from failed nodes, minimizing response delaysCan be suppressed.
[0071]
According to invention of Claim 6,,It is possible to reduce the probability of data loss of a request due to a signal collision or overflow of a reception buffer.
[0076]
Claim7According to the described invention, LegendIt is possible to avoid congestion of the communication system such as when traffic exceeding the communication capacity or data reception capability of the transmission medium occurs.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a response distributed communication method according to a first embodiment of the invention.
FIG. 2 is a diagram illustrating a configuration example of a communication system.
FIG. 3 is a diagram illustrating an example of a frame format of data transmitted and received in the communication system.
4 is a hardware configuration diagram of each node illustrated in FIG. 2; FIG.
FIG. 5 is a functional block diagram provided on the hardware shown in FIG. 4, particularly on the control unit;
FIG. 6 is an explanatory diagram of a response distributed communication method according to a second embodiment of the present invention.
FIG. 7 is a diagram illustrating another example of response collection;
FIG. 8 is an explanatory diagram of a response distributed communication method according to a fifth embodiment of the invention.
FIG. 9 is an explanatory diagram of a response distributed communication method according to a sixth embodiment.
FIG. 10 is an explanatory diagram of problems such as data loss when a plurality of nodes perform transmission.
[Explanation of symbols]
1 Communication system
2 network
3 nodes
30 Transmitter
31 Receiver
32 timer
33 memory
34 Control unit

Claims (7)

A communication method for distributing responses of each of the plurality of nodes in a communication system in which a plurality of nodes mutually transmit and receive data,
Each of the plurality of nodes is
Have a unique value assigned with a timer ,
As a step of transmitting a response, the step of starting the timer, the step of delaying the transmission timing according to the unique value, and the step of transmitting the response in a predetermined frame at the transmission timing,
As a step of sending a response to a request sent by another node during collection of a response of a certain node, after the timer started at the time of sending a request corresponding to the response of the given node, A response distribution comprising: delaying transmission timing in accordance with a value; and transmitting the response in a predetermined frame in response to a request transmitted by the other node at the transmission timing. Communication method. A communication method for distributing responses of each of the plurality of nodes in a communication system in which a plurality of nodes mutually transmit and receive data,
Each of the plurality of nodes is
Each has its own value assigned and a list of nodes that expect to return a response and have a timer, respectively,
Step for sending a request, a step of activating the timer, a step by using the list to include in at least one of header information designation information of the destination node to send the request, the header information the request possess and transmitting at a predetermined frame with,
As a step for transmitting a response, when a request is received in a predetermined frame, a step of determining whether or not header information in the predetermined frame is addressed to itself, and if the determination result is addressed to itself, Delaying transmission timing according to the unique value, and transmitting the response in a predetermined frame at the transmission timing;
When a request is retransmitted, if a response is received from all of the nodes expected to return the response included in the header information of the request before a timeout occurs due to the timing of the timer, the timer And when a time-out occurs due to timing of the timer before receiving a response from all of the nodes that expect the response to be returned, a response is returned from the nodes that expect the response to be returned. Retransmitting the request only to nodes that have not been
If a response is not returned from the retransmission partner even if the request is retransmitted a predetermined number of times in the step of retransmitting the request as a step of troubleshooting the failed node, the partner node is designated as the failed node. And in the step of retransmitting the request, the step of reducing the number of retransmissions for the failed node to be less than the number of retransmissions for a node not handled as the failed node. response distributed type communication how to said. A communication method for distributing responses of each of the plurality of nodes in a communication system in which a plurality of nodes mutually transmit and receive data,
Each of the plurality of nodes holds a unique value assigned thereto, and as a transmission function, when transmitting a response in a predetermined frame, a response transmission function that delays the transmission timing of the response according to the specific value And a request transmission function for transmitting the request without delaying the transmission timing when transmitting the request in a predetermined frame ,
Among the plurality of nodes, at least one node requests larger than that of another node for transmission of data and high-priority node, the response from the high priority nodes than the response from the other nodes If the communication system is set to be transmitted first, and no response is returned from the high priority node to the other nodes, the collection of responses is interrupted to the high priority node. response distributed type communication how to characterized in that to perform a retransmission of the request. A communication method for distributing responses of each of the plurality of nodes in a communication system in which a plurality of nodes mutually transmit and receive data,
Each of the plurality of nodes is
Having a communication event cycle timer and a response reception completion waiting timer, and having a node number as an assigned unique value, and a connection list that lists node numbers of the node and node numbers of other nodes,
As a step when setting, the node number of the own node and the node number in the connection list are compared, the transmission order of the response of the own node is calculated, and according to the number of nodes connected to the communication system And setting each time measured by the communication event cycle timer and the response reception completion waiting timer,
Step for sending a response, to avoid calculating the residence time in the transmission medium response from the transmission rate and the data length of the response of the transmission medium, the congestion of the communication system from the residence time of that calculating a transmission time interval of the response required, the transmission order and the response distributed in accordance with the transmission time interval you wherein <br/> that a step of transmitting the response at a given frame Communication method. Each of the plurality of nodes, when the number of failed nodes increases, shortens the length of each time measured by the communication event period timer and the response reception completion waiting timer before the number of failed nodes increases. The response distributed communication method according to claim 4 . The load of the communication system is calculated from the reception time of a predetermined frame, and it is determined whether or not the load of the communication system has increased from this load. If the load of the communication system has increased, the response transmission time response distributed type communication method according to any one of claims 1 to 4, characterized in that a longer interval. 7. The communication system according to claim 1, wherein a plurality of nodes transmit / receive data to / from each other .

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