TW201434286A - Relay apparatus and relay method - Google Patents

Abstract

A relay apparatus (200) is provided with: a network interface (201) that receives a packet transmitted from a controller (100) and a buffer transmission unit (211), which stores the packet received by the network interface (201) and transmits the stored packet to a network (400) with a previously set transmission cycle, and which, at a time when a packet to be transmitted at subsequent packet transmission timing determined on the basis of the transmission cycle is not stored, transmits a notification packet to the network (400) at the subsequent transmission timing, said notification packet notifying that there is no transmittable packet.

Description

Relay device and relay method

The present invention relates to a relay device and a relay method for relaying packets. In particular, there are relay devices and relay methods for transmitting data, and data is transmitted at regular intervals without any wobble.

In an embedded system used in a train, a power plant, or a factory, as a controller of a processing device, a node such as a sensor and an actuator is connected via a network. The controller periodically transmits an information collection instruction to the node. The node responds to instructions from the controller. In this embedded system, especially in the case of performing the following applications (1) and (2), it is usually required that the interval at which the controller transmits data is fixed (referred to as periodicity).

(1) The actuators connected to each node or each node operate synchronously.

(2) According to the requirements of the controller, correctly sample the information of the node.

The data transfer of the controller usually oscillates due to the delay of the data bus within the controller, resulting in failure to meet the required periodicity.

In Patent Document 1, when a controller and a node are connected, a swing absorbing device is provided between the two to ensure periodicity. The swing absorbing device buffers the packets transmitted by the controller and transmits them at fixed time intervals measured by the oscillating absorbing device to absorb the swing of the controller data transfer. When the data transfer interval from the controller is short and dense, the main purpose of the method of Patent Document 1 In the extended interval, the transmission load of the node is reduced. However, there is no special mention of the case of data transmission from the controller between the fixed time intervals measured by the swing absorption device.

Nodes in an embedded system typically wait for the controller to transmit data at regular intervals to act on the controller's data transfer. According to the method described in Patent Document 1, each node waits for a data transfer between waiting for a fixed time interval even if there is no data transfer from the controller. In other words, there will be problems that cannot ensure the periodicity required by embedded systems.

Further, in the case where there is no data transmission from the controller within a fixed time interval, Patent Document 2 and Patent Document 3 provide a method of transmitting an empty packet and an error packet. However, the manners of Patent Document 2 and Patent Document 3 do not specifically mention the case where the data transfer is advanced. Therefore, when the data transfer from the controller is advanced, in this case, data transfer is performed at each node. This can interfere with the fixed time interval that each node waits, and there is a problem that the periodicity required by the embedded system cannot be ensured.

[Prior patent documents] [Patent Literature]

[Patent Document 1] JP-A-2005-318075.

[Patent Document 2] Japanese Laid-Open Patent Publication No. Hei 08-265357.

[Patent Document 3] JP-A-2007-058495.

As described above, in an embedded system, a node usually waits for a controller to transmit data (periodic data transfer) at a fixed time interval for action based on data transfer by the controller. However, according to the manner described in Patent Document 1, when data transmission from the controller has no fixed time, each node continues to wait for data transfer from the controller. In other words, the periodicity required by embedded systems cannot be guaranteed. According to the manner described in Patent Document 2 and Patent Document 3, when data transmission from the controller is advanced, each node receives data in advance before the waiting time interval. In other words, the periodicity required by embedded systems cannot be guaranteed.

The main object of the present invention is to solve the above problems, and its purpose is to ensure the requirements of the embedded system, that is, the periodicity of data transmission from the controller.

The relay device of the present invention comprises: a receiving unit that receives a control packet transmitted by the controller; and a buffer transmitting unit that stores the control packet received by the receiving unit and presets the stored control packet The transmission cycle is transmitted to the network, and at the same transmission timing of the control packet determined by the transmission cycle, when no control packet to be transmitted is stored, the notification packet is transmitted to the network at the next transmission timing. To notify that there are no control packets that can be transmitted.

In accordance with the apparatus provided by the present invention, the requirements of the embedded system, i.e., the periodicity of data transfer from the controller, can be ensured.

100‧‧‧ Controller

101‧‧‧ processor

102‧‧‧ chipsets

103‧‧‧ memory

104‧‧‧Network Controller

105‧‧‧Network I/F

106‧‧‧Memory bus

107‧‧‧Internal busbar

200‧‧‧Relay device

201, 207‧‧‧Network I/F (Interface)

202‧‧‧buffer

203‧‧‧Communication Agreement Setting Department

204‧‧‧Period measurement department

205‧‧‧Setting the register

206‧‧‧Timer

208‧‧‧Swing Judgment Department

211, 212‧‧‧ Buffer transfer department

300‧‧‧ nodes

300-1‧‧‧Actuator

301‧‧‧Microcomputer

302‧‧‧Special communication chip

303‧‧‧I/O (input/output)

304‧‧‧ memory

305‧‧‧Internal busbar

400‧‧‧Network

810‧‧‧CPU (Central Processing Unit)

811‧‧‧ROM (read only memory)

812‧‧‧RAM (random access memory)

813‧‧‧ display device

814‧‧‧ operation keys

816‧‧‧Communication埠

820‧‧‧ storage device

821‧‧‧OS (Operating System)

823‧‧‧Program Group

824‧‧‧Archives

825‧‧ ‧ busbar

Fig. 1 is a block diagram showing an embedded system 1000 of the first embodiment.

Fig. 2 is a block diagram showing the internal portion of the controller 100 of the first embodiment.

Fig. 3 is a block diagram showing the internal structure of the node 300 of the first embodiment.

Fig. 4 is a block diagram showing the inside of the relay device 200 of the first embodiment.

Fig. 5 is a view for explaining the operation of the relay device 200 of the first embodiment.

Figure 6 illustrates the general operation of the relay device.

Fig. 7 is a block diagram showing the internal portion of the controller 100 of the second embodiment.

Fig. 8 is a view showing the operation of the relay device 200 of the second embodiment.

Fig. 9 is a block diagram showing the hardware of the relay device 200 of the third embodiment.

The following is the first embodiment. The first embodiment will be described using the first to sixth figures. Fig. 1 is a block diagram showing an embedded system 1000 of the first embodiment. The controller 100 and the three sets of nodes 300 are networked through the relay device 200.

Figure 2 is a block diagram showing the internals of the controller 100. The controller 100 can also be implemented using a personal computer. The controller 100 is composed of a general architecture of a general purpose computer. As shown in FIG. 2, the controller 100 has a processor 101, a chipset 102, a memory 103, a network controller 104, and a network interface 105 (hereinafter referred to as an I/F interface). The memory bus 106 is used to connect the chip set 102 and the memory 103. The internal busbar 107 is used to connect the chipset 102 and the network controller 104.

Figure 3 is a block diagram showing node 300. In general, in most cases, the node 300 of the embedded system employs a simple architecture such as a dedicated communication chip 302. As shown in Figure 3, node 300 has a microcomputer 301, dedicated A communication chip 302, an I/O (input/output) 303, and a memory 304 are used, and are connected by an internal bus 305. Further, the I/O 303 is connected to the actuator 300-1.

Fig. 4 is a block diagram showing the relay device 200 of the first embodiment. In the first embodiment, the embedded system 1000 is characterized by a relay device 200. As shown in FIG. 4, the relay device 200 includes a network I/F 201 (an example of a receiving unit) on the controller 100 side, a buffer 202, a communication protocol setting unit 203, a period measuring unit 204, and a setting register 205. The timer 206 and the network I/F 207 on the network side. The buffer 202 and the timer 206 constitute a buffer transfer unit 211 for transmitting packets to the network 400.

(1) The network I/Fs 201 and 207 are connectors for connecting to the network 400 and communication circuits for outputting packets. Through network 400, network I/F 201 receives packets from controller 100. Through the network 400, the network I/F 207 relays the packets received from the controller 100 to the node 300.

(2) The buffer 202 temporarily stores the packets received from the network 400 or intended to be transmitted to the network 400.

(3) The communication protocol setting unit 203 is configured to set a communication protocol specified by the packet attribute to display the content of the notification packet 20 spontaneously transmitted by the relay device 200, and the type and number of packets to be relayed to the network 400. . The information of the communication protocol setting unit 203 can be set in advance according to communication of the controller 100 or the like, or can be dynamically reset.

(4) The period measuring unit 204 is configured to measure the period of the packet transmitted by the controller 100.

(5) The setting register 205 is used to set the relay device 200 to transmit the packet. Time timer period. The period in which the register 205 is set can be preset according to communication or the like of the controller 100, or can be dynamically reset.

(6) Based on the timer period set by the setting register 205, the timer 206 measures the elapsed time from the point in time when the buffer 202 retransmits the packet to the node 300 via the network 400. When the measurement is completed, the timer cycle time that has passed has been notified to the buffer 202 while the measurement is reset and the measurement is started again.

FIG. 5 illustrates the processing of the relay device 200 for correcting the wobble of the packet transmitted by the controller 100. The horizontal axis represents time. The operation of the relay device 200 will be described with reference to FIG. The controller 100 generates a packet (control packet) transmitted to each node 300 based on the interrupt of the timer (period T(1)). The generated packet is transmitted from the network I/F 105 to the relay device 200. At this time, due to factors such as delay of the internal bus bar 107, delay of uncertainty, and the like, the period T(1) corresponding to the packet transmission interval of the controller 100 starts to oscillate. The wobble of the packet will be described using FIG. Based on the interrupt of the timer (period T(1)), the controller 100 generates the packets 10a-1, 10a-2, the packets 10a-3, and 10a-4, and transmits the packets from the network I/F 105. The packets 10b-1 to 10b-4 are used to indicate packets transmitted from the network I/F 105. In Fig. 5, the transmission intervals of the packets 10b-1 and the like transmitted from the network I/F 105 to the relay device 200 are not uniform. In other words, the packet 10b-1 transmitted from the network I/F 105 is swung. Further, the packet 10a-1 is a packet group composed of one or more packets, and the other packets 10a-1 to 10a-4 are also the same.

The network I/F 201 of the relay device 200 receives the packets 10b-1 to 10b-4 and the like in which the wobble has occurred from the network I/F 105 of the controller 100. The buffer 202 is used to store packets received by the network I/F 201. At the same time, in the middle Following device 200, internal timer 206 measures the transfer timing for transmitting packets received from controller 100 to network 400. After the timer 206 reaches the timer period (indicated as the period T(2)), the buffer 202 transmits the stored one or more packets to the network 400 according to the communication protocol (information) of the protocol setting unit 203. Refer to Figure 5 for illustration. It is assumed that the network I/F 201 receives the packet 10b-2. Since the relay device 200 is transmitting the packet 10c-1, the timer 206 measures the elapsed time from the packet 10c-1. When the elapsed time measured by the timer 206 has reached the transmission period T(2), at this point in time, the packet 10c-2 is transmitted to the network 400 in accordance with the communication protocol of the protocol setting unit 203.

(Communication Agreement of the Communication Protocol Setting Unit 203)

The communication protocol setting unit 203 is configured to set a communication protocol specified by the packet attribute to display the number and type of packets to be relayed to the network 400. The buffer 202 acknowledges the communication protocol when transmitting the packet 10c-2. In the communication protocol of the communication protocol setting unit 203, when the specification "transfers 10 or more packets", if the packet 10c-2 is a packet group composed of 20 packets, the buffer 202 transmits the packet 10c-2. If the packet 10c-2 is only one packet, the buffer 202 does not transmit the packet 10c-2. The buffer 202 transmits the notification packet 20 described below without transmitting.

(notification packet)

As shown in FIG. 5, when the timer period of the relay device 200 has been reached, if the buffer 202 does not have any packets to be transmitted, or the number is insufficient, and there is no packet type to be transmitted (ie, no In accordance with the communication protocol, the notification packet 20 is generated based on the communication protocol set by the protocol setting unit 203, and the generated notification packet 20 is transmitted to the network 400 and the controller 100. Further, in a broad sense, when there are insufficient packets and different types of packets, it is also "no packet to be transmitted". In Fig. 5, after the packet 10c-3 is transmitted, at the time point when the transmission period T(2) has elapsed, it is indicated that there is no packet to be transmitted. To this end, the relay device 200 transmits the notification packet 20 to the network 400 and the controller 100 (the point in time at step S101). The notification packet 20 contains delay information from the packet transmission of the controller 100. The information of the notification packet 20 may be an empty packet or a packet containing information for identifying an error or the like.

The controller 100 and the node 300 receive the processing after notifying the packet 20, and may also be processed in any manner. For example, when the controller 100 and the node 300 determine that an error has occurred, the operation may also be stopped. Alternatively, the controller 100 may also reset to make the transmission period T(1) of the packet longer. Further, the notification packet 20 may not be transmitted to the controller 100.

(Period measurement unit 204)

Preferably, the period T(2) of the setting register 205 is coincident with the period T(1) of the controller 100. However, only the relay device 200 and the controller 100 are set to have the same cycle value, and it is difficult to measure the exact same cycle due to the frequency deviation of the oscillator used by the relay device 200 and the controller 100. To this end, the period measuring unit 204 is for correcting the difference between the period T(2) set by the setting register 205 of the relay apparatus 200 and the transmission period T(1) of the controller 100. That is, the relay device 200 makes the period in which the slave device 100 actually receives the packet coincides with the transmission period T(2) in which the received packet is transmitted to the node 300 as much as possible. The period measuring unit 204 measures the packet transmission period from the controller 100 a sufficient number of times. Specifically, the period measuring unit 204 measures the transmission period when the network I/F 201 receives the packet from the controller 100. In Figure 5 In other cases, the period measuring unit 204 measures the reception interval of the packet 10b-1 and the packet 10b-2, the reception interval of the packet 10b-3 and the packet 10b-4, and the like. The cycle measuring unit 204 sets the average value of the measurement results to the setting register 205 of the relay device 200. Further, the average value is an example. Based on the measurement result, the period measuring unit 204 can determine the period set by the setting register 205. Therefore, the timer period T(2) of the relay device 200 can be approximated to the actual transmission period of the controller 100. The above processing is used to make the relay device 200 coincide with the cycle of the controller 100, or as an initial process, before the embedded system 1000 is actually operated, or dynamically when the embedded system 1000 is operated. For example, when the dynamic process is performed, the period measuring unit 204 compares the calculated average value with the period set by the setting register 205, and when the difference between the two is greater than the critical value, the calculated average value is regarded as new. The cycle is set to the setting register 205.

The timer 206 that starts measuring the relay device 200 can also start immediately after receiving the packet from the controller 100. Alternatively, if the packet transmission swing from the controller is large, the timer period may be delayed by half.

As described above, the packet transmitted by the controller 100 is first stored in the buffer 202 by the relay device 200, and transmitted to the network in accordance with the timer period T(2) in the relay device 200. Further, between the timer period T(2), when there is no packet transmission from the controller 100, or when the packet is insufficient, the relay device 200 according to the information (the communication protocol) of the communication protocol setting unit 203, The notification packet 20 is transmitted to the network 400. As such, each node 300 is typically capable of receiving packets within a fixed time interval.

Figure 6 illustrates the general processing of the relay device. Figure 6 is similar In Figure 5. As shown in FIG. 6, between the measurement timer periods of the relay device 200, when there is no packet transmission from the controller 100, the notification packet 20 is not transmitted, but the transmission delay (delay time A) is 10c. -4. To this end, each node 300 needs to continue to wait for packet transmissions from controller 100. That is, each node 300 is typically capable of receiving packets within a fixed time interval.

Alternatively, although not shown in FIG. 6, when the packet transmission from the controller 100 is advanced, the relay device 200 transmits the packet to the network, and each node 300 needs to receive at intervals shorter than the waiting interval. Packet. That is, each node 300 is typically capable of receiving packets within a fixed time interval.

According to the first embodiment, each node 300 is generally capable of receiving packets from the controller 100 at regular intervals and is capable of ensuring periodicity.

The following is the second embodiment. The relay device 200 of the second embodiment will be described using Figs. 7 to 8. Fig. 7 shows the relay device 200 of the second embodiment. Fig. 8 is a view for explaining the function of the following wobble determination unit 208. Figure 8 is similar to Figure 5. In the relay device 200 of the second embodiment, the wobble determining unit 208 is further provided in the relay device 200 with respect to the relay device 200 of the first embodiment. In the relay device 200 of the second embodiment, the buffer 202, the timer 206, and the wobble determination unit 208 constitute a buffer transfer unit 212.

In the relay device 200 of the first embodiment, when the transmission timing determined by the timer period T(2) set by the setting register 205 has reached without any packet to be transmitted, the notification packet 20 is transmitted. Therefore, when the packet transmission swing from the controller 100 is large, the notification packet 20 can be frequently transmitted according to the measurement start timing of the timer 206 of the relay device 200. For example, in the case of frequently transmitting the notification packet 20, the node 300 and the embedded The stop time of the entry system 1000 may become longer.

Refer to Figure 8 for illustration. The swing determination unit 208 determines whether or not the delay of packet transmission from the controller 100 is within an allowable range (allowable period). Whether or not the allowable range of the wobble is set in advance (indicated as α in the second embodiment) depends on the communication from the controller 100, and can be dynamically changed.

As shown in FIG. 8, during the timer period T(2), when the relay device 200 cannot receive the packet from the controller 100, for example, after the packet 10c-2 is sent out, when the next transmission timing has been When there is no packet 10c-3 to be transmitted, the buffer 202 is only allowed to be allowed in the range α. In other words, from the transmission time point of the packet 10c-2, the buffer 202 does not notify the transmission of the packet 20, but waits for the packet transmission from the controller 100 until the allowable range of the oscillation (T(2) + α )until. When receiving the packet 10b-3 from the controller 100 within the allowable range of the wobble (T(2) + α(1), α(1) < α), the buffer 202 takes the received packet 10b-3 as Packet 10c-3 is then transmitted to the network. Alternatively, the buffer 202 may determine whether or not to transmit according to the communication protocol of the communication protocol setting unit 203. Until the allowable range of the swing (T(2) + a), if the packet from the controller 100 is still not received, the buffer 202 will notify the packet 20 to be transmitted to the network. In the case of Fig. 8, since α(2) > α, the notification packet 20 is transmitted.

As described above, the wobble determination unit 208 is provided in the relay device 200, thereby ensuring the communication periodicity within the allowable range (α of the second embodiment), and in the case where the notification packet 20 is frequently transmitted, the node can be shortened. 300 and system stop time.

The following is the third embodiment. The third embodiment will be described using Fig. 9. The third embodiment describes a hardware configuration of the relay device 200 as the first embodiment of the computer and the second embodiment. FIG. 9 shows an example of hardware resources of the relay device 200.

Further, in the hardware resource shown in FIG. 9, the relay device 200 has a CPU (Central Processing Unit) 810 for executing a program. The CPU 810 is connected to the ROM (read only memory) 811, the RAM (random access memory) 812, the display device 813, the operation keys 814, the communication port 816 (an example of I/F), and the storage device 820 via the bus bar 825 ( An example of a buffer) is used to control these hardware devices. The ROM 811, the RAM 812, and the like are examples of a register and a buffer.

RAM 812 is an example of volatile memory. The storage medium such as the ROM 811 and the storage device 820 is an example of non-volatile memory. The communication port 816, the operation key 814, and the like are examples of an input unit and an input device. Further, the communication port 816, the display device 813, and the like are examples of an output unit and an output device. The communication port 816 is connected to the network.

The storage device 820 stores an operating system (OS) 821, a program group 823, and a file group 824. The program of the program group 823 is executed by the CPU 810 and the operating system 821.

The above-mentioned program group 823 stores the execution program of the function of the "~ part" described in the above embodiment. The program is read and executed by the CPU 810.

Further, in the description of the above embodiments, the description of "~" can also be described as "~method", and can also be described as "~step", "~program", and "~flow". In other words, the implementation of the "~ department" explained It can be pure soft body, or combined with soft body and hard body, and can be combined with firmware. The firmware and software are stored in a storage medium in a programmatic manner. The program is read by the CPU 810 and executed by the CPU 810. In other words, the program "~" is used to operate the computer. Or, execute the above-mentioned "~ Department" program and method on the computer.

Although the relay device 200 has been described above by way of the embodiments, the relay device 200 can be understood from the above description by using the computer as the relay device 200 and operating the program. Furthermore, according to the above description, the operation of each "~" of the relay device 200 can be clearly understood, and it is a relay method of the packet.

The above embodiment is for explaining the following relay device 200. The relay device 200 transmits the packet transmitted by the controller 100 to the network according to the timer period, and transmits the notification packet to the controller 100 and the network 400 when the timer period has expired without any packet to be transmitted.

The above embodiment is for explaining the following relay device 200. The relay device 200 has a period measuring unit 204 that measures the interval of packets transmitted by the controller 100 and sets the average value of the measured values to the timer period of the relay device 200. The cycle measuring unit 204 can make the timer period of the controller 100 and the relay device 200 close to each other.

The above embodiment is for explaining the following relay device 200. If the delay of the packet transmission from the controller 100 is within the allowable value (allowable period α), the relay device 200 transmits the packet to the network 400, and if the delay exceeds the allowable value, the notification packet 20 is transmitted to the controller 100 and Network 400.

100‧‧‧ Controller

200‧‧‧Relay device

201, 207‧‧‧Network I/F

202‧‧‧buffer

203‧‧‧Communication Agreement Setting Department

204‧‧‧Period measurement department

205‧‧‧Setting the register

206‧‧‧Timer

211‧‧‧Buffer transfer department

300‧‧‧ nodes

400‧‧‧Network

Claims (7)

A relay device for transmitting a control packet transmitted by a controller into a packet group consisting of one or more packets, and relaying to a node through a network, wherein the relay device includes: a receiving unit, which is received a control packet transmitted by the controller; and a buffer transmission unit storing the control packet received by the receiving unit, and transmitting the stored control packet to the network in a preset transmission cycle, and simultaneously in the transmission cycle In the next transmission sequence of the determined control packet, when no control packet to be transmitted is stored, the notification packet is transmitted to the network at the next transmission timing to notify that there is no control packet that can be transmitted. The relay device according to claim 1, wherein the relay device includes: a period measuring unit that measures a receiving interval when the receiving unit receives a control packet from the controller, and measures the receiving interval according to the receiving interval As a result, the transfer cycle is set. The relay device according to claim 2, wherein the period measuring unit calculates an average value of the measured values of the receiving intervals, and sets the calculated average value as the transfer period. The relay device according to any one of claims 1 to 3, wherein, in the next transmission sequence, when no control packet to be transmitted is stored, the time from the arrival of the next transmission sequence At the beginning of the point, the buffer transfer unit stands by for the transmission of the notification packet during the allowable period, and does not transmit when there is a control packet to be transmitted from the elapse of the next transmission sequence and within the allowable period. The notification packet transmits the stored control packet to the network, and when the allowable period has expired, no control packet needs to be transmitted. The notification packet is transmitted, and wherein the time point at which the control packet or the notification packet is transmitted is used as the starting point of the transmission period. The relay device according to any one of claims 1 to 4, wherein the relay device further comprises: a communication protocol setting unit configured to set a relevant property of the control packet to be transmitted to the network In the communication protocol, the buffer transmission unit determines whether there is a control packet to be transmitted according to the communication protocol set by the communication protocol setting unit. The relay device according to any one of claims 1 to 5, wherein the buffer transfer unit transmits the notification packet to the controller. A relay method is used for transmitting a control packet transmitted by a controller into a packet group consisting of one or more packets, and relaying to a node through a network, wherein the relay method includes: receiving, receiving by the receiving unit And a control packet transmitted by the controller; and the buffer transmission unit stores the control packet received by the receiving unit, and transmits the stored control packet to the network in a preset transmission cycle, and at the same time, the control determined by the transmission cycle In the next transmission sequence of the packet, when no control packet to be transmitted is stored, the notification packet is transmitted to the node at the next transmission timing to notify that there is no control packet that can be transmitted.