JP2013110586A - Communication system, communication device, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the processing load of reception data on a CPU by only making network superordinate software of the CPU controlling a communication device process data necessary for its own device.SOLUTION: A communication device having received a transmission frame from another communication device determines whether or not the communication device should perform reception processing of the received frame by getting a reception frame discard determination means 439 to compare a destination IP address and destination port number as a destination number which is the information included in the received frame with a destination IP address and destination port number indicating whether or not the communication device may perform reception processing stored in a storage device in the communication device. A LAN controller driver 421 will perform discard processing of the frame if the received frame is not a frame of which the communication device should perform reception processing, and network superordinate software 411 will perform frame reception processing if the received frame is a frame of which the communication device should perform reception processing.

Description

  The present invention relates to a communication system, a communication apparatus, and a communication method, and in particular, a communication system, a communication apparatus, and a communication method configured by connecting a plurality of communication apparatuses on the same network suitable for process control and the like. About.

  Generally, a plant control system or the like controls a plant via a control terminal connected to each communication device of a communication system configured such that a plurality of communication devices are communicably connected via a network. . Each communication device in such a communication system periodically transmits the contents of the main memory in the communication device to other communication devices, so as to match the contents of the main memory of all communication devices in the network, Communication is performed cyclically at a predetermined cycle. Transmission of data by such communication is performed by broadcasting in order to guarantee the simultaneity of data in a plurality of communication devices connected to the network.

  FIG. 3 is a diagram for explaining the configuration of a communication apparatus according to the prior art and data transfer between the communication apparatuses. FIG. 3 shows two communication devices. Data transfer will be described with one communication device as a transmission side and the other communication device as a reception side. Note that a larger number of communication devices are connected to the network, although not shown.

  In FIG. 3, the communication apparatus A 200 on the transmission side includes a CPU A 201, an LSI A 202, a main memory A 203, and a LAN controller A 204. The CPUA 201 and the LSIA 202, the LSIA 202 and the main memory A203, and the LSIA 202 and the LAN controller A204 are connected by a bus. Further, when receiving data from another communication device, the LAN controller A 204 can notify the CPU A 201 that the data has been received from the other communication device by outputting an interrupt signal 205 to the CPU A 201.

  Similarly to the communication device A, the communication device B 210 on the receiving side includes a CPU B 211, an LSI B 212, a main memory B 213, and a LAN controller B 214. A bus is connected between the CPUB 211 and the LSIB 212, between the LSIB 212 and the main memory B213, and between the LSIB 212 and the LAN controller B214. In addition, when receiving data from another communication device, the LAN controller BA214 can notify the CPUB 211 that the data has been received from the other communication device by outputting an interrupt signal 215 to the CPUB 211.

  In the above description, the LSIA 202 and LSIB 212 have an interface function between the CPUs A 201 and B 211 and the LAN controllers A 204 and B 214.

  In the main memory A203 of the communication device A200, data storage areas are delimited by boundaries, and data 1 (207) is transmitted in the data 1 area 206 and data 2 (209) is transmitted in the data 2 area 208. Each data to be stored is stored in each area. When the communication apparatus A 200 transfers data to the communication apparatus B 210 or another communication apparatus by broadcast via the network 220, the CPU A 201 of the communication apparatus A 200 issues a broadcast transmission execution command to the LAN controller A 204 via the LSI A 202. Upon receiving the command, the LAN controller A 204 reads the target data in the main memory A 203 via the LSIA 202, generates a frame in which the read data is placed on the data frame, and the frame 221 is connected to the network 220. Broadcast transmission to each communication device.

  The LAN controller B 214 of the communication device B 210 receives the frame 221 from the communication device A 200, and writes the data in the frame 221 to the data area as a reception buffer of the main memory B 213 via the LSI B 212. When the write to the main memory B 213 is completed, the LAN controller B 214 outputs an interrupt signal 215 to notify the CPU B 211 that the data reception has been completed. This interrupt signal is output to the CPU B 211 every time the LAN controller B 214 receives one frame from another communication device. When the network upper software (not shown) provided in the CPU B 211 detects an interrupt signal from the LAN controller B 214, it calculates the sum of the received data in the received frame, such as IP and UDP required by the processing program on the receiving side, and receives it. Copy data from the buffer to the work area of the network upper software, and determine whether to discard unnecessary data in the local communication device.

  For example, the techniques described in Patent Document 1, Patent Document 2, and the like are known as conventional techniques of the communication apparatus as described above.

Japanese Patent Laid-Open No. 06-274463 JP-A-62-254545

  Since the above-described prior art performs communication of data by broadcasting between communication devices, the upper network software of the CPU that controls the communication device performs sum calculation such as IP and UDP on the received data, from the reception buffer. Data is copied to the work area of the upper network software, and unnecessary data is discarded by the local communication device. For this reason, in the above-described prior art, when the frequency of receiving broadcast frames increases, the frequency of interrupts from the LAN controller of the communication device on the receiving side to the CPU also increases, and data reception processing by the network upper software of the CPU The load on the CPU becomes very large, and the processing load on the CPU itself becomes very large.

  That is, in a communication system in which a plurality of communication devices are connected on the same network, when a communication device on the network transmits data by broadcast, the data is transmitted to all communication devices. Therefore, if data transmission by broadcast is frequently performed, the communication device is forced to receive and process a large amount of data unnecessary for the local station. The communication device uses the network upper software to calculate the sum of IP, UDP, etc. for all the received data, copy from the reception buffer to the work area of the network upper software, discard unnecessary data in its own communication device, etc. Processing must be performed, and the larger the amount of data to be received, the higher the load on the CPU that controls the communication device.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and to enable the network upper software of the CPU that controls the communication device to process only the data necessary for the own communication device. An object of the present invention is to provide a communication system, a communication apparatus, and a communication method that can reduce the data processing load.

  According to the present invention, the object is to provide a communication system in which a plurality of communication devices are communicably connected to each other via a network, each of the plurality of communication devices having a network upper software and a LAN controller driver. An arithmetic processing unit, a main memory, a received frame discard determination unit, and a discard status register for temporarily storing information indicating whether or not to discard a transmission frame are stored in the main memory. In order to make the received data coincide with the data held by the other communication device, the communication device mutually transmits and receives the transmission frame, and the communication device that receives the transmission frame transmitted from the other communication device discards the received frame. Destination IP address as destination number, which is information included in transmission frame received by determination means The destination port number is compared with the destination IP address and the destination port number indicating whether or not the own communication device stored in the storage device of the own communication device may perform the reception process, and the received transmission frame is It is determined whether or not reception processing should be performed by the own communication device, the determination result is held in the discard status register, and the LAN controller driver accepts the received transmission frame by the discard status register. When it is indicated that processing is not to be performed, the transmission frame is discarded, and the network upper software indicates that the received transmission frame is to be accepted by the communication apparatus. In this case, this is achieved by performing the transmission frame accepting process.

  According to the present invention, the network upper software of the CPU that controls the communication device of the communication device that has received the data broadcast from another communication device needs to process only the data necessary for the communication device. , The processing load on the received data of the CPU can be reduced.

It is a figure explaining the structure of the communication system by one Embodiment of this invention, and the data transmission by a broadcast. FIG. 2 is a diagram for explaining an operation in which each communication device receives data broadcast from all communication devices other than its own communication device in the communication system shown in FIG. 1. It is a figure explaining the structure of the communication apparatus by a prior art, and the transfer of the data between communication apparatuses. It is a figure which shows the structure of the format of the frame header which shows the typical data block in a frame header. It is a block diagram which shows the structure of the communication apparatus by embodiment of this invention. 10 is a flowchart for explaining processing operations until a received frame discard determination block performs discard determination and a LAN controller driver discards a frame. It is a figure explaining a response | compatibility with each case in the reception buffer area | region of a main memory, and a data discard status register.

  Embodiments of a communication system, a communication apparatus, and a communication method according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram for explaining the configuration of a communication system and data transmission by broadcast according to an embodiment of the present invention.

  The communication system according to the embodiment of the present invention is configured such that a plurality of communication devices A to D including a communication device A100 are connected to each other via a network 101 so that they can communicate with each other. Control terminals A to D are connected to the communication devices A to D, respectively. Although FIG. 1 shows that each of the communication devices A to D is connected to one control terminal A to D, a plurality of communication terminals A to D are provided. Control terminals may be connected. When the illustrated communication system is used for process control, each control terminal collects various sensor information in the process and controls various actuators.

  Now, it is assumed that the communication apparatus A 100 performs data broadcast transmission 102. In this case, the data is transmitted to all the communication devices connected to the network 100 and received by all other communication devices. The data broadcast transmission is performed in the same way as in the communication apparatus A100 in the communication apparatus B110 and all other communication apparatuses.

  FIG. 2 is a diagram for explaining an operation in which each communication device receives data broadcast from all communication devices other than its own communication device in the communication system shown in FIG.

  Also in the communication system according to the embodiment of the present invention, each communication device receives all data regardless of whether the broadcast-transmitted data is necessary for the own communication device station. The embodiment of the present invention, as will be described in detail later, determines whether or not the received data is necessary or unnecessary for the own communication device so as not to increase the processing load on the CPU that controls the communication device. Data is being discarded.

  The configuration of the communication system according to the above-described embodiment of the present invention is the same as that of the related art. Further, although the network of the communication system according to the above-described embodiment of the present invention is illustrated as being connected in a loop shape, the network configuration does not necessarily have to be a loop shape.

  Next, a communication device according to an embodiment of the present invention will be described. Before that, a frame header of a frame generated when one of a plurality of communication devices connected to a network transmits data to another communication device. The structure of will be described.

  FIG. 4 is a diagram showing a format structure of a frame header showing a typical data block in the frame header. In the embodiment of the present invention, discard determination of a frame, that is, data is performed based on the value in the frame header of the frame received by the LSI in the communication apparatus. Transmission data is stored in a data area following the frame header.

  As shown in FIG. 4, the frame header includes a MAC header 300 including a destination MAC address, a source MAC address, and a frame type as defined in IEEE 802.3, a protocol number, a source IP address, and a destination. An IP header 310 including an IP address, and a UDP header 320 including a transmission source port number and a destination port number having information required by the processing program of the reception side apparatus are configured. In the embodiment of the present invention, the frame type 301 in the MAC header, the protocol number 311 in the IP header, the destination IP address 312, and the destination port number 321 in the UDP header are data blocks that are subject to frame discard determination. Whether or not to discard the frame is determined based on the contents of these data blocks.

  FIG. 5 is a block diagram showing the configuration of the communication apparatus according to the embodiment of the present invention. FIG. 5 shows the configuration of the communication device A100, but the plurality of communication devices that constitute the communication system are all configured identically.

  The communication apparatus according to the embodiment of the present invention includes a CPU 410, a main memory 420, an LSI 430, and a LAN controller 440 as hardware. The CPU 410 includes, as software, network upper software 411 that performs processing after data reception notification, and a LAN controller driver 412 that performs data reception notification to the network upper software 411 and discards received data. These software 411 and 412 are controlled and executed by the CPU 410 to construct respective functions.

  Although details of the configuration of the main memory 420 are not shown, a transmission data storage area, a reception buffer area, a reception data storage area, a local station (local communication device) reception permission port number designation bit area, and other processing, etc. FIG. 5 shows the data received from the local station reception permission port number designation bit area 421 and other communication devices via the network and the LAN controller 440. Only the reception buffer area 422 for storing the data is shown.

  The local station reception permission port number designation bit area 421 has a capacity of 65536 bits (8192B) in accordance with all 65536 types of port numbers defined by the standard, and the head of the local station reception permission port number designation bit area area. The port number 0 and the final port number 65535 are set, and the user who is the manager who manages the system sets 1 to the local station reception permission port number designation bit position corresponding to the port number for which reception is permitted.

  The reception buffer area 422 is a ring buffer, and is an area for storing the reception frame 450 received from the other communication device received by the LAN controller 440 for each case 423 that is a reception frame. The capacity of one case 423 is 2 KB which is larger than the maximum length 1518B of the reception frame 450 and is a power of 2 that can be easily associated with a data discard status register described later.

  The LSI 430 includes a discard status register 431 that reflects the data discard status, a main memory address register 432 of the reception buffer that specifies the start address of the reception buffer area 422 of the main memory 420 that stores the reception frame 450, and a header of the reception frame 450 Frame type address register 433 for specifying where the frame type 301 is located, protocol number address register 434 for specifying where the protocol number 311 in the header of the received frame 450 is located, A destination IP address address register 435 for specifying where the destination IP address 312 in the header is located, a subnet mask setting register 436 for setting a subnet mask for the destination IP address, a reception frame A destination port number address register 437 for designating where the destination port number in the header of the program 450 is located, a bit area main memory address register 438 for designating the head address of the local station reception permission port number designation bit area 421, In addition, a reception frame discard determination block 439 is provided.

  The received frame discard determination block 439 is executed in parallel while the header of the frame 450 received from another communication device via the LAN controller 440 is stored in the corresponding case 423 of the reception buffer storage area 422 of the main memory 420. The frame type 312, the protocol number 311, the destination IP address 312, and the destination port number 321 in the header of the received frame 450 are sequentially snooped based on the addresses specified in the registers, and the data is to be discarded each time. It is determined whether or not. Whether the destination port number is to be discarded is determined by reading the local station reception permission port number designation bit area 421 of the main memory 420 and comparing it with the read data. The reception frame discard determination block 439 performs the above-described determination, and when the reception frame 450 is a discard target, sets the target bit of the discard status register 431 to 1.

  The LAN controller 440 stores the received frame 450 in the reception buffer area 422 of the main memory 420, and then outputs an interrupt signal notifying the LAN controller driver 412 of the completion of reception.

  When receiving the interrupt notification, the reception LAN controller driver 412 reads the discard status register 431 to determine whether the discard status is raised, that is, whether the target bit of the discard status register 431 is set to 1. To check. As a result of this check, if the frame 450 is not to be discarded, the LAN controller driver 412 notifies the network upper software 411 that performs processing such as IP and UDP to receive the frame 450, and if the frame 450 is to be discarded, the LAN controller driver 412 receives The received frame 450 is discarded, and reception notification of frame reception to the network upper software 411 is not performed. Note that discarding of the received frame 450 by the reception LAN controller driver 412 is not limited to notifying the reception of frame reception to the network upper software 411. This is because the reception buffer 422 is used cyclically, and is discarded in order from the old case.

  After receiving the reception notification from the LAN controller driver 412, the network upper software 411 performs processing such as sum calculation of the received frame such as IP and UDP, and copying from the reception buffer to the work area of the network upper software. As described above, the network upper software 411 may perform processing such as sum calculation of IP, UDP, etc. of a frame not to be discarded and copy from the reception buffer to the work area of the network upper software. It is no longer necessary to perform sum calculation such as IP and UDP, copy to work area, and data discard for data, and even when data transmission by broadcast frequently occurs from other communication devices, compared to the case of the prior art The processing load on the network upper software, that is, the processing load on the CPU 411 is reduced.

  FIG. 6 is a flowchart for explaining processing operations until the received frame discard determination block 439 performs discard determination and the LAN controller driver 412 discards the frame. Next, referring to FIG. 6, the received frame is discarded. The process will be described in detail. In the example of the flow shown in FIG. 6 in the embodiment of the present invention, the frame type of the received frame is IP, the protocol number is UDP, the destination IP address is broadcast, and the destination port number is not local station reception permission. In this case, the received frame is discarded.

(1) The LAN controller 440 detects the head of the received frame from the reception standby state of the frame 450 from another communication device (steps 500 and 501).

(2) The frame header of the received frame is input to the LSI 430 in order from the top. The received frame discard determination block 439 of the LSI 430 snoops data in which the value of the frame type address register 433 matches the address of the received frame 450, and determines whether or not the frame type is IP. There are two types of frame types, IP and ARP. If the frame type is ARP, the process returns from step 500 to enter a frame reception standby state (step 502).

(3) If the frame type is IP in the determination in step 502, the received frame discard determination block 439 snoops data in which the value of the protocol number address register 434 matches the address of the received frame, It is determined whether or not the protocol number is UDP. If the protocol number is other than UDP, the process returns from step 500 to a frame reception standby state (step 503).

(4) If it is determined in step 503 that the protocol number is UDP, the reception frame discard determination block 439 snoops data in which the value of the address register 435 of the destination IP address matches the address of the received frame, The snooped data is masked with the value designated by the subnet mask setting register 436 (step 504).

(5) Thereafter, the received frame discard determination block 439 determines whether or not the destination IP address is broadcast. If the destination IP address indicates an individual destination and is not broadcast, the process starts from step 500. Returning to the process, a frame reception standby state is entered (step 505).

(6) If it is determined in step 505 that the destination IP address is broadcast, the reception frame discard determination block 439 snoops data in which the value of the address register 437 of the destination port number matches the address of the reception frame. At the same time, the case number of the reception buffer is snooped by comparing the address of the reception frame with the value of the main memory address register 432 of the reception buffer (step 506).

(7) Next, the received frame discard determination block 439 reads the local station reception permission port number designation bit area 421 of the main memory corresponding to the snooped destination port number, and the corresponding local station reception permission port number designation bit area. Whether the snoop destination port number is to be discarded, whether the destination port number is the local reception permission port number, and the frame is not to be discarded If the frame is not to be discarded, the process returns from step 500 to a frame reception standby state (steps 507 and 508).

(8) If it is determined in step 508 that the frame is to be discarded, the frame type, protocol number, destination IP address, and destination port number all indicate that the received frame is to be discarded. 1 is set in the discard status register 431 corresponding to the snooped reception buffer case number. Note that the frame is determined to be discarded even if the frame type, protocol number, destination IP address, and destination port number do not indicate that the received frame is to be discarded. There may be only a part (step 509).

(9) When the reception of the frame 450 from another device is completed, the LAN controller 440 issues an interrupt notification notifying the LAN controller driver 412 of the completion of reception. If the received frame is instructed to be discarded by reading the value of the discard status register 431, the received frame data is discarded, and the process returns to step 500 to receive the frame. A standby state is entered (step 510).

  In the communication apparatus according to the embodiment of the present invention, the LAN controller driver 412 discards the frame data to be discarded and performs the frame reception notification to the network upper software 411 by performing the processing described above. There is no.

  For this reason, the network upper software 411 only needs to perform processing such as sum calculation of frames that are not to be discarded, such as IP and UDP, and copying from the reception buffer to the work area of the network upper software. On the other hand, it is not necessary to perform sum calculation such as IP and UDP, copy to work area, and data discard, and even when data transmission by broadcast frequently occurs from other communication devices, it is higher in the network than in the case of the prior art. The processing load on the software 411, that is, the processing load on the CPU 410 is reduced.

  FIG. 7 is a diagram for explaining the correspondence between each case in the reception buffer area 422 of the main memory 420 and the data discard status register 431. In the example shown in FIG. 7, as shown in FIG. 7A, it is assumed that the capacity of the reception buffer 601 in the area of the main memory 600 is 128 KB, that is, the maximum number of received frames is 64 cases. Further, the number of bits of the data discard status register 610 is set to 64 bits in total to be equal to the number of cases of the reception buffer as shown in FIG. 7B.

  In FIG. 7, when received data from another station communication device stored in case 0 (602) of the reception buffer is to be discarded, 1 is set to the 63rd bit 611 which is the most significant bit of the data discard status register 610. Is done. When the received data from another communication device stored in the case 63 (603) of the reception buffer is to be discarded, 1 is set to the 0th bit (612) which is the least significant bit of the data discard status register 610. The The LAN controller driver reads such a register value and determines whether or not the received data is to be discarded.

  The processing in the above-described embodiment of the present invention is configured by a program and can be executed by a CPU included in the present invention. These programs are stored in a recording medium such as an FD, CDROM, or DVD and provided. And can be provided by digital information over a network.

100, 110 Communication devices A and B
101 Network 400 Communication device A
410 CPU
411 Network upper software 412 LAN controller driver 420 Main memory 421 Local station reception permission port number designation bit area 422 Reception buffer 423 Case N
430 LSI
431 Discard status register 432 Receive buffer main memory address register 433 Frame type address register 434 Protocol number address register 435 Destination IP address address register 436 Subnet mask setting register 437 Destination port number address register 438 Bit area main memory Address register 439 Received frame discard decision block 440 LAN controller 450 frame

Claims (6)

In a communication system configured such that a plurality of communication devices are connected to each other via a network,
Each of the plurality of communication devices temporarily stores a central processing unit having network upper software and a LAN controller driver, a main memory, a received frame discard determination unit, and information indicating whether or not to discard a transmission frame. A discard status register, and transmission / reception of transmission frames to each other in order to match the data held in the main memory with the data held by other communication devices,
In the communication device that has received the transmission frame transmitted from another communication device, the received frame discard determination means determines that the destination IP address and the destination port number as the destination number, which is information included in the received transmission frame, The own communication device stored in the storage device of the communication device compares the destination IP address and the destination port number indicating whether or not the acceptance processing may be performed, and the received communication frame is accepted by the own communication device. It is determined whether or not to be performed, the determination result is held in the discard status register,
The LAN controller driver, when the discard status register indicates that the received transmission frame is not to be accepted in its own communication device, performs the discard process of the transmission frame,
A communication system, wherein the network host software performs reception processing of the transmission frame when the received transmission frame indicates that reception processing is to be performed by a local communication device.   The received frame discard determining means uses a frame type and a protocol number in addition to the destination number as information used for determining whether or not the received transmission frame should be accepted in the local communication device. The communication system according to claim 1.   3. The communication system according to claim 1, wherein each bit of the discard status register is associated with an area of the main memory storing the received individual transmission frame.   4. The communication system according to claim 3, wherein an area of the main memory for storing each received transmission frame is larger than the maximum length of the transmission frame and is a power of two. In a communication device in a communication system configured such that a plurality of communication devices are connected to each other via a network,
Each of the plurality of communication devices temporarily stores a central processing unit having network upper software and a LAN controller driver, a main memory, a received frame discard determination unit, and information indicating whether or not to discard a transmission frame. A discard status register, and transmission / reception of transmission frames to each other in order to match the data held in the main memory with the data held by other communication devices,
In the communication device that has received the transmission frame transmitted from another communication device, the received frame discard determination means determines that the destination IP address and the destination port number as the destination number, which is information included in the received transmission frame, The own communication device stored in the storage device of the communication device compares the destination IP address and the destination port number indicating whether or not the acceptance processing may be performed, and the received communication frame is accepted by the own communication device. It is determined whether or not to be performed, the determination result is held in the discard status register,
The LAN controller driver, when the discard status register indicates that the received transmission frame is not to be accepted in its own communication device, performs the discard process of the transmission frame,
The network host software performs the transmission frame reception process when the received transmission frame indicates that the reception process is to be performed by the local communication apparatus. In a communication method in a communication system configured such that a plurality of communication devices are connected to each other via a network,
Each of the plurality of communication devices temporarily stores a central processing unit having network upper software and a LAN controller driver, a main memory, a received frame discard determination unit, and information indicating whether or not to discard a transmission frame. A discard status register, and transmission / reception of transmission frames to each other in order to match the data held in the main memory with the data held by other communication devices,
In the communication device that has received the transmission frame transmitted from another communication device, the received frame discard determination means determines that the destination IP address and the destination port number as the destination number, which is information included in the received transmission frame, The own communication device stored in the storage device of the communication device compares the destination IP address and the destination port number indicating whether or not the acceptance processing may be performed, and the received communication frame is accepted by the own communication device. It is determined whether or not to be performed, the determination result is held in the discard status register,
The LAN controller driver, when the discard status register indicates that the received transmission frame is not to be accepted in its own communication device, performs the discard process of the transmission frame,
The communication method according to claim 1, wherein when the received transmission frame indicates that the received communication frame is to be received by the communication apparatus, the network upper software performs the reception process of the transmission frame.

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