JP2007067922A - Filtering repeat function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve network efficiency by lowering a network occupation ratio of a subordinate network, by deciding the kind of a communication frame to be relayed by the relay station and relaying only necessary information. <P>SOLUTION: A communication system is constituted by connecting a master station which has a communication function, and one or a plurality of slave stations each having a communication function are connected by a bus type network and interposing relay stations in one or two or more stages on a path connecting the master station and a specified slave station on the bus type network. Various communication frames transmitted by the master station and slave stations each include identification information for identifying the kind of the frame. Each relay station has a means for deciding the kind of a received communication frame based upon the identification information of the communication frame, and relaying only communication frames required to be relayed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a communication system for controlling an FA device or the like that includes a master station that manages a network, a slave station that controls I / O, and a relay station that shapes and amplifies a communication frame in a bus network. Is.

  A remote I / O network of a programmable controller composed of a single master station, a plurality of slave stations, and a plurality of relay stations is already known. An example of the network is shown in FIG.

  As shown in the figure, this network system is roughly composed of a master station 70, slave stations 80a to 80d (slave # 1 to 4), and relay stations 90a to 90d (repeaters # 1 to 4). A relay station (repeater) is a network configured with two stages.

  A programmable controller (PLC) is a control unit (hereinafter referred to as a CPU unit) that executes a user program, and an input / output unit (hereinafter referred to as I / O device as a generic term for both devices) connected to an input device and an output device (hereinafter referred to as an I / O device). Each unit includes a communication master unit that connects a remote I / O network and communicates I / O data with a slave station. The master station may be regarded as corresponding to a programmable controller or may be regarded as corresponding to a communication master unit. In the figure, the programmable controller is represented as a master station. This network is configured as a bus network, and the master station manages the network and is incorporated in the programmable controller. The slave station is connected to an I / O device (not shown), controls the output device based on the OUT data stored in the communication frame received from the master station, and responds to requests from the master station. The IN data fetched from the input device is stored in a response frame and returned to the master station. The relay station performs waveform shaping and amplification processing on communication frames transmitted and received on the network. For this reason, the trigger frame transmitted from the master station to each slave station and the response frame from each slave station undergo a shaping / amplification process every time they pass through the relay station, so a certain time delay (repeater delay) Will occur. FIG. 20 shows an operation model showing the trigger frame transmitted by the master station and the response frame responded by each slave station in time series at the observation points A, B, C, and D shown in FIG. .

  As shown in FIG. 17, slave station # 1 is connected to the master station without passing through the relay station. Therefore, since the response of the slave station 80a at the observation point A in FIG. 20 does not cause a repeater delay, the response frame from the slave station 1 is transmitted with the end of the trigger frame from the master station. On the other hand, a relay station exists between the slave station 2 and the master station, and two relay stations exist between the slave stations 3 and 4 and the master station. Therefore, a repeater delay occurs every time the trigger frame transmitted to the slave stations 2, 3 and 4 passes through the relay station, and a repeater delay also occurs every time the response frames from those slave stations pass through the relay station. Will occur. For this reason, conventionally, in consideration of the repeater delay that occurs in the relay station, as shown in the figure, a gap is left in the response of each slave so that the responses do not collide (for example, Patent Document 1). reference).

  Similarly, at the observation points B, C and D shown in FIG. 17, in order to cope with the repeater delay, as shown in FIG. To send.

Further, since the system is a bus type system, the relay station relays all communication frames flowing upstream and downstream. In the system configuration as shown in FIG. 17, the response frame of slave station # 3 arrives at the master station or another slave station via four relay stations (relay stations 90d, 90c, 90a, 90b). Then, it arrives at slave station # 4. At this time, the arrival at the slave station # 4 is after “repeater delay × 4” time. For this reason, in order to avoid the collision of response frames from all the slave stations, it is necessary to leave a gap of time corresponding to “repeater delay × 4” on the average at the observation point A. . Therefore, the communication cycle is
Communication cycle = trigger frame time
+ (Response frame time + repeater delay x maximum number of repeater stages x 2)
× Slave number.

Furthermore, as described above, the conventional relay station relays all communication frames flowing upstream and downstream. More specifically, for example, the response frame transmitted from the slave station # 1 shown in FIG. 20 is not only transmitted to the master station, but also to other slave stations # 2, 3, 4 via the relay station. It was also relayed to. This is clear from the fact that the response frame from the slave station # 1 is known at all of the observation points A, B, C, and D. Similarly, response frames from all slave stations are known at all observation points A, B, C, and D.
JP 2004-280304 A

  In the conventional method, the repeater delay generated at each relay station is taken into consideration so that there is a gap between the responses of each slave station so that the responses do not collide with each other. There has been a problem of increasing the number of people.

  In addition, the communication frame addressed to the master station transmitted from each slave station on the network is also relayed to other slave stations, resulting in an increase in the occupation rate of the communication path, leading to a decrease in communication performance. .

  The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to provide a relay station capable of preventing the responses of the slave stations from colliding with each other without increasing the communication cycle. It is an object of the present invention to provide a method for reducing the influence of delay and a system for realizing the method.

  Another object of the present invention is to determine the type of communication frame to be relayed by a relay station on the network and relay only necessary information, thereby reducing the network occupancy ratio below the relay station. , To improve network efficiency.

  Another object of the present invention is to detect the reverse connection state when the upper port and the lower port of the relay station are connected in reverse on the network, and from the state. An object of the present invention is to provide a relay station having a function of automatically returning to normal.

  Other objects and operational effects of the present invention will be easily understood by those skilled in the art by referring to the following description of the specification.

  According to an embodiment of the present invention, a master station that is a PLC having a communication function and one or more slave stations that are I / O terminal devices having a communication function are connected by a bus network, and the bus type In a communication system in which a relay station functioning as a repeater is interposed in one or more stages on a path connecting a master station and a predetermined slave station on a network, the master station and the slave station The various communication frames transmitted by the mobile station contain identification information for identifying the type of the frame, and the relay station determines the type of the communication frame based on the identification information of the received communication frame, and relays it. Means for performing relay processing only on communication frames that require processing.

  With such a configuration, each relay station identifies a communication frame that needs to be relayed and a communication frame that does not need to be relayed, and performs relay processing only for the communication frame that needs to be relayed (filtering repeat). As a result, unnecessary network occupancy can be deleted and network efficiency can be improved.

  According to the embodiment of the present invention, the relay station has setting means for switching whether each communication frame is a communication frame for relay processing or a communication frame for which relay processing is not performed.

  With this configuration, it is necessary to change a communication frame that is set to need to be relayed to a communication frame that does not need to be relayed, or vice versa. It is possible to arbitrarily change the setting. Since the communication frame to be relayed can be arbitrarily changed by setting as described above, various customizations and fine adjustments can be performed after the network is constructed.

  According to the embodiment of the present invention, the relay station can provide a period during which no relay process is performed.

  With such a configuration, it is possible to set so that relay processing is not performed only for a predetermined period (time) set in advance, and an independent network is created in the network only for the set period, and within the independent network The high-speed communication can be realized, and the relay process is resumed when a predetermined time elapses. Therefore, it is easy to return the created independent network to the network.

  According to an embodiment of the present invention, a master station that is a PLC having a communication function and one or more slave stations that are I / O terminal devices having a communication function are connected by a bus network, and the bus type In a communication system in which a relay station functioning as a repeater is interposed over one or more stages on a path connecting a master station and a predetermined slave station on a network, the relay station receives Means for identifying the type of communication frame to be performed, means for determining whether to perform relay processing on the communication frame according to the type of communication frame identified, and communication frames determined to perform relay processing, Means for executing a relay process.

  With such a configuration, each relay station does not need to identify a communication frame that needs to be relayed and a communication frame that does not need to be relayed, and perform a relay process only on the communication frame that needs to be relayed. Thus, it becomes possible to provide a relay device (relay station) that can eliminate the network occupation and improve the network efficiency.

  According to the embodiment of the present invention, the relay device further includes switching means for switching the setting of a communication frame that performs relay processing and a communication frame that does not perform relay processing.

  With this configuration, it is necessary to change a communication frame that is set to need to be relayed to a communication frame that does not need to be relayed, or vice versa. It is possible to provide a relay device that can be arbitrarily changed to the setting. By using such a relay device, the communication frame to be relayed can be arbitrarily changed by setting, so that various customizations and fine adjustments can be made after the network is constructed.

  According to the embodiment of the present invention, the relay device can be set not to perform the relay process for a predetermined period.

  With such a configuration, a relay apparatus that can be set so as not to perform relay processing only for a predetermined period (time) set in advance is realized, and a network that is located downstream from the relay station only for the set period It is possible to create an independent network within the entire network and realize high-speed communication within the independent network. Furthermore, when the predetermined time elapses, the relay processing of the relay device that has stopped the relay processing is resumed, so that the created independent network can be easily returned to the entire network.

  According to the embodiment of the present invention, the relay device includes an upper port connected to the upstream side of the network and a lower port connected to the downstream side, and the upper port and the lower port are connected to the network in reverse. It has reverse connection detection means for detecting a case where it is jammed.

  With such a configuration, it becomes possible to quickly detect problems such as deterioration in network efficiency caused by connecting the upper port and the lower port to the network in reverse, or malfunction of the network itself.

  According to the embodiment of the present invention, in the relay device, the upper port and the lower port are respectively connected to the upstream and downstream of the network via two common selectors, and the upper port and the lower port are reversed to the network. When a connected state is detected, it is possible to switch the function between the upper port and the lower port by two selectors, and even if a reverse connection is detected, the normal connection state is automatically restored. To do.

  With such a configuration, even if reverse connection of the upper port and lower port of the relay device is detected, the relay station automatically returns to the normal state, so that the user's hand is not bothered. In addition, even if a reverse connection of the relay station occurs, it is automatically detected and recovery processing is performed, so it is not necessary to pay attention to the connection direction of the upper and lower ports of the relay station during network configuration, improving work efficiency. To do.

  As is clear from the above description, according to the present invention, the relay station installed on the network identifies the communication frame to be relayed and does not perform unnecessary frame relay, so that the network efficiency is improved, and the relay station Even if the network is connected in the reverse direction to the network, the reverse connection is detected and automatically returned to the normal state, so that there is an advantage that the work efficiency is improved without bothering the user.

  In the following, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  An overall configuration diagram of a programmable controller system (PLC system) including a communication master station and a communication slave station is shown in FIG. As shown in the figure, this PLC system includes a PLC device 1 having a communication function as a communication master station, and I / O terminal devices 2, 2... Having a plurality of communication functions as communication slave stations. Are connected by a field bus 6 which is a bus network. In the figure, 4 is a repeater that functions as a relay device, and 5 is a termination device that reduces reflection at the end of the fieldbus.

  The illustrated PLC device 1 has a large number of connectors arranged on a backplane (not shown) on which a parallel bus is laid, and a CPU unit, an I / O unit, various other high-performance units, etc. are connected to these connectors. A so-called building block type PLC device that can be arbitrarily attached is employed. In particular, in this example, a “PLC device having a communication function” is configured by attaching a communication master unit to one connector on the backplane. In the figure, among these units, only the CPU unit 20 and the communication master unit 10 are denoted by reference numerals.

  A hardware configuration diagram showing an internal configuration of the communication master unit 10 is shown in FIG. As shown in the figure, the communication master unit 10 includes a communication interface (communication I / F) 101 that functions as a communication physical layer, and a master ASIC 102 that is a circuit that realizes a desired communication function as an LSI. , A buffer area for transmission / reception data transferred to / from the CPU unit 20, a RAM 103 functioning as a calculation work area for the CPU 104, which will be described later, and a CPU 104 that is configured mainly by a microprocessor and controls the entire apparatus. A nonvolatile memory (EEPROM) 105 in which various setting data are stored, an LED display 106 for performing various operation displays, a setting switch 107 used for various setting operations, and a CPU unit Internal bus interface that functions as an interface to the internal bus leading to 20 Esu and an (internal bus I / F) 108.

  As is well known to those skilled in the art, in this type of PLC system, the CPU unit 20 repeatedly executes a common process, an I / O refresh process, a user program execution process, a peripheral service process, and the like. When executing the I / O refresh process, the I / O refresh process is performed not only between the local I / O unit mounted on the backplane but also with the RAM 103 in the communication master unit 10. Execute.

  Specifically, the OUT data in the I / O memory of the CPU unit 20 is written to the OUT area in the RAM 103 of the communication master unit 10, and the IN data in the RAM 103 is stored in the I / O memory of the CPU unit 20. Written in the IN area.

  On the other hand, as will be described in detail later, communication via the field bus 6 is performed between the communication master unit 10 and each I / O terminal device 2 asynchronously with the I / O refresh operation of the CPU unit 20. As a result, a kind of I / O refresh process is also executed between each I / O terminal device 2 and the RAM 103 in the communication master unit 10.

  Specifically, the IN data received from the I / O terminal device 2 is written into the IN area of the RAM 103 in the communication master unit 10, and the CPU unit 20 takes in from the communication master unit 10 by the I / O refresh operation. The CPU unit 20 executes the user program based on the IN data, and sets the execution result as OUT data. The CPU unit 20 sends OUT data to the communication master CPU unit by the I / O refresh operation. The communication master unit 10 stores the OUT data in the OUT area of the RAM 103. Then, the communication master unit 10 transmits OUT data in the OUT area of the RAM 103 to the corresponding I / O terminal device 2 asynchronously with the I / O refresh.

  In this way, the I / O refresh process is executed between the I / O memory in the CPU unit 20 and each I / O terminal device 2, 2,... As described above, the CPU unit 20 can control the I / O devices connected to the remotely installed I / O terminal devices 2, 2.

  Next, FIG. 3 shows a hardware configuration diagram inside the I / O terminal device. As shown in the figure, the I / O terminal device 2 is a master for an LSI that includes a communication interface (communication I / F) 201 functioning as a communication physical layer and a circuit for realizing a desired communication function. An ASIC 202, a CPU 203 mainly composed of a microprocessor for controlling the entire apparatus, a nonvolatile memory (EEPROM) 204 for storing various setting data, and an LED display for displaying various operations Device 205, setting switch 206 used for various setting operations and the like, I / O unit 207 for exchanging data with I / O device 7, and a stabilized DC power supply for the entire apparatus And a DC power supply unit 208 having a transforming function.

  Then, between the communication master unit 10 and each I / O terminal device 2, through 1-N master-slave communication with the communication master unit 10 as a communication master station and each I / O terminal device 2 as a communication slave station. , I / O data is exchanged.

  Specifically, the OUT data received from the communication master unit 10 is sent to the I / O device 7 (output device) via the I / O unit 207 of the I / O terminal device 2, and the I / O device The IN data taken into the I / O terminal device 2 via the I / O unit 207 from 7 (input device) is transmitted to the communication master unit 10.

  Next, FIG. 4 shows a hardware configuration diagram inside the repeater functioning as a relay device. As shown in the figure, the repeater 4 is mounted between the communication interfaces 401 and 402 connected to the master side and the slave side, and the data (signal) transmitted between the communication interfaces 401 and 402, respectively. It includes a repeater ASIC 403 that performs predetermined processing, and a CPU 407 that is configured mainly by a microprocessor and controls the entire apparatus. Furthermore, a power supply unit 404 is provided that steps down the input voltage (24 V) to 5 V and supplies power to each element in the repeater 4. Furthermore, an LED display unit 405 indicating an operating state (communication state), abnormality / normality, and a setting switch 406 for setting a node address and the like are provided.

  In the delay reduction of the repeater (relay station) in the present invention, it is preferable that each relay station on the network recognizes the installation position (that is, the network configuration) on the network. In the network configured as described above, an example of a network configuration information teaching method for a search route of an information frame to be transmitted will be described.

  The communication master station (M), the communication slave station (S), and the relay station (R) described above with reference to FIG. 1 have unique addresses on the PLC system network. Individual identification is performed by this address. The network configuration information teaching method of the present embodiment is applied from network startup management to normal communication.

  First, the relay station (R) to the relay station (R) and the relay station (R) to the slave station (S) through the first frame broadcasted simultaneously (one-to-N communication) from the master station (M). ), The relay station (R) and the slave station (S) generate and store the “upper neighbor station information of the own station” in the network.

  This operation may be performed at a stage before the master station recognizes the relay station and slave station connected to the network, such as when the power is turned on, or the master station is connected to the network during network operation. It may be optionally performed at a stage after recognizing the connected relay station and slave station.

  In this embodiment, a search frame (Beacon_Frame: hereinafter abbreviated as BF) is used. A block diagram showing the frame format of the BF is shown in FIG.

  As shown in the figure, the BF flowing through the field bus 6 includes a BF identification header 501 for identifying the BF, and a relay station that is updated with the address value of the relay station every time it passes through the relay station. It includes at least an address 502, a relay station counter 503 whose value is incremented by +1 every time it passes through the relay station, and a transmission speed 504 indicating the communication transfer speed of the BF.

  The communication master station (M) broadcasts the BF simultaneously so that the BF is transmitted to all relay stations and communication slave stations (S) connected to the network. Then, the BF that has been broadcast simultaneously reaches the slave station (S) directly, or reaches the slave station via one or more relay stations. At this time, although the BF flowing through each path is slightly delayed by the line delay time of the path and the relay delay time of the passing relay station, it can be considered that the BF reaches each relay station and each slave station at almost the same time as a whole. it can.

  An explanatory diagram (part 1) of the frame transmission / reception sequence is shown in FIG. As shown in the figure, from the master station (address 10), a BF having a relay station address value of “10” and a relay station counter value of “0” is broadcast on the network. The

  When the relay station (address 100) receives the broadcasted BF from its upper port, the value “10” of the relay station address 502 in the BF and the value “10” of the relay station counter 503 are read from the BF. And stored in a memory in the relay station (address 100). As a result, the relay station (address 100) can recognize the relative position of its own station, assuming that the station address of the station adjacent to the upper side is “0”. In this case, the content of “upper neighbor information of own station” generated by the relay station (address 100) is “upper neighbor information of own station” (station address “10”).

  Thereafter, the value of the relay station address 502 in the BF is replaced with “100” (relay station address: own station address) from “10” (master station address: the station address of the station adjacent to the upper side). . At the same time, the value “0” of the relay station counter 503 is incremented by +1 to “1”. Thus, a new BF in which the value of the relay station address 502 is rewritten and the value of the relay station counter 503 is incremented by +1 is transmitted from the lower port to the slave station (address 101) located in the next stage. .

  When the slave station (address 101) receives the BF transmitted from the relay station (address 101), the value “100” of the relay station address 502 and the value “1” of the relay station counter 503 in the BF are read from the BF. , Stored and held in a memory in the slave station (address 101). As a result, the slave station (address 101) can recognize the relative position of its own station, assuming that the station address of the station adjacent to the upper side is “100”. In this case, since the station address of the station adjacent to the upper side is “100”, the content of the “higher side neighboring station information of the own station” generated by the slave station (address 101) Side adjacent station information "(station address" 100 ").

  In this way, when the information storage phase (phase I) is executed, the master station (address 10) to the relay station (address 100), the relay station (address 100) via the BF broadcast simultaneously from the master station. ) From the slave station (address 101) to the relay station (address 100), the relay station (address 100) and the slave station (address 101) are respectively notified of the higher-level neighboring station information and the relay station counter in the network. Values are generated and stored.

  In the example shown in FIG. 6, only one relay station is interposed between the master station and the slave station, but two or more relay stations are interposed between these stations. Even when no relay station is interposed between the master station and the slave station, the operation of each relay station and each slave station is the same.

  FIG. 7 shows a processing flow (No. 1) when the relay station receives BF. The process shown in this flow is executed by the CPU 407 in the repeater 4 shown in FIG.

  In the figure, when processing is started, first, frame reception standby processing is executed (step 701). In this state, when any frame is received (YES in step 702) and it is determined that the frame is BF based on the BF identification header 501 of the frame (YES in step 703), the following processing (steps 704 to 709) is performed. Are executed sequentially.

  First, the frame is analyzed and the structure of the frame is recognized (step 704). Next, address information (relay station address 502) and counter information (relay station counter 503) in the frame are read out and stored in a predetermined memory (steps 705 and 706). Next, the address information (relay station address 502) in the frame is replaced with its own address (step 707). Next, the counter information (relay station counter 503) in the frame is replaced with a value incremented by +1 (step 708). Finally, the new frame thus obtained is output to the lower port (709).

  FIG. 8 shows a processing flow (No. 1) at the time of BF reception of the communication slave station. The processing shown in this flow is executed by the CPU 203 in the I / O terminal device 2 shown in FIG.

  In the figure, when processing is started, first, frame reception standby processing is executed (step 801). In this state, when any frame is received (YES in step 802) and the frame is determined to be a BF header based on the BF identification header 501 of the frame (YES in step 803), the following processing (steps 804 to 806) is performed. It is executed sequentially.

  First, the frame is analyzed, and the structure of the frame is recognized (step 804). Next, in-frame address information (relay station address 502) and in-frame counter information (relay station counter 503) are read out and stored in a predetermined memory as “upper neighbor information of own station” (step 805). 806).

  In this way, each of the relay station and the slave station generates and stores the higher-side neighboring station information of the own station and the relay station counter value in the network, and this information is fed back to the master station. The system diagram of the entire system can be grasped.

  Next, a method for reducing a repeater delay generated in a relay station on a network, which is a main part of the present invention, will be described in detail with reference to FIGS. In these figures, reference numeral 30 is a master station, 40a to e are slave stations (parts 1 to 5), 50a and b are relay stations (parts 1 and 2), 31 is a network trunk line, and 32 is a network trunk line. Network branch lines 1 and 33 branch from the network trunk line, and network branch lines 2 branch from the network trunk line respectively.

  In the PLC system according to the present invention, a dedicated frame (for example, BeaconFrame, OutFrame, TrgFrame) issued only from the master station to the slave station described below, and a dedicated frame issued only from the slave station to the master station There is a frame (for example, ConnectionFrame, InFrame), a frame that is emitted in both directions (for example, EventFrame), the relay station distinguishes the frame type, and the relay station transfers only in the necessary direction. .

  As shown in FIG. 10 and FIG. 11, the PLC system in the present embodiment shapes a master station 30 that manages a network, a slave station 40 that controls I / O, and a communication frame in a bus network. -It is comprised from the relay station 50 to amplify.

  The basic structure of each frame is shown in FIG. As shown in the figure, each frame has a start code 901 indicating that the frame starts, a frame identification header 902 indicating the type of the frame, frame data 903 indicating the content of the frame, and a check indicating the validity of the frame. It includes at least four elements of code 904 (CRC data or the like). When the relay station 50 on the network recognizes the start code 901, it shapes the waveform and starts output to the other port. By shaping this waveform, it is possible to extend the laying distance of the network.

  However, when relay processing is performed at the stage where the start code 901 is determined, data transmitted from the slave station 40 to the master station 30 is also relayed to other slave stations. However, the data was transmitted and the occupation efficiency of the network was reduced.

  FIG. 10 shows a case where frame transmission from the master station 30 to the slave station 40 is performed. Since the frame from the master station 30 to the slave station 40 is a broadcast frame, it can be handled by relaying all the frames simultaneously. As shown in the figure, a frame transmitted from the master station 30 is transmitted not only to the slave station 40a but also to the slave station 40d and the slave station 40e via the relay station 50a. Although not shown, the data is also transmitted to the slave station 40b and the slave station 40c via the relay station 50b.

  On the other hand, FIG. 11 shows a case where frame transmission from the slave station 40 to the master station 30 is performed. As shown in the figure, for example, when a frame is transmitted from the slave station 40d to the master station 30, the relay station 50a shapes and amplifies the frame and transmits the frame to the master station 30. However, conventionally, the relay station 50b simultaneously receives the frame and transmits the frame to the lower port. For this reason, the slave stations 40b and 40c have not been able to secure the network idle time that can be transmitted to the master 30 station, and the network communication efficiency has been reduced.

  FIG. 12 shows the network occupation ratio in the above case. As shown in the figure, a frame addressed to the master station from the slave station 40d arranged on the network branch line 32 is relayed from the network branch line 32 by the relay station 50a and sent to the network trunk line 31 to be the master station. 30. However, it is transmitted to the master station 30, relayed by the relay station 50b installed on the network branch line 33, and transmitted to the slave station 40b. The frame originally from the slave station 40d addressed to the master station is also transmitted to the slave station 40b via the network branch line 32 and the relay station 50b. As a result, the frame addressed to the master station 30 is relayed from the slave station 40d on the network branch line 33, resulting in an extra occupation, and the transmission of the frame addressed to the master station 30 from the slave station 40b is delayed accordingly. ing.

  Although not shown in the figure, a frame transmitted from the slave station 40b to the master station 30 is also transmitted to the slave stations 40d and 40e via the relay station 50a, and an extra set work is placed on the network branch line 32. Occupation occurred.

  FIG. 13 shows a case where a frame received by each relay station is identified and unnecessary relay processing is not performed. It is clear by comparing FIG. 12 with FIG. 12, but the relay station 50b identifies the frame addressed to the master station 30 from the slave station 40d and prevents the relay process from being performed, so that the network on the network branch line 33 It is possible to smoothly transmit a frame addressed to the master station 30 from the slave station 40b without causing extra network occupation. Thus, by determining the frame identification header at the relay station and performing the relay process only in the necessary direction, the communication time of the network branch line 33 can be secured, the slave stations 40b and 40c can communicate, and the network efficiency is improved. An improvement can be realized. Here, it is described that the communication time of the network branch line 33 is secured, but it goes without saying that the efficiency of the entire network is improved by performing the same processing in other relay stations.

  FIG. 14 shows a functional block diagram of a relay station that identifies frames and prevents unnecessary relaying as described above. As shown in the figure, each relay station has an upper port 411 and a lower port 417 connected to the network by a bidirectional serial bus.

  First, a case where a frame is transmitted from the upper port 411 side will be described. The frame (received data) sent to the upper port 411 via the bidirectional serial bus is sent to the start code detector 412. The received data is accumulated in the data buffering unit 413 from the start code detection unit 412 and later sent to the repeat frame generation unit 416. At this time, the start code detection unit 412 transmits the reception data to the data buffering unit 413 and also transmits the reception data and the start code detection signal to the frame type identification unit 414. Next, when a start code detection signal is sent to the frame type identification unit 414, the type of the frame is identified, and the identification result is sent to the lower repeat control unit 415 as a frame type information signal. The lower repeat control unit 415 determines whether the received frame is a repeat target frame according to the type of frame specified by the frame type information signal.

  The determination method in the lower repeat control unit 415 is as follows. As described above, each relay station on the network knows its own position on the network and a relative position with other relay stations and slave stations by using the network configuration information teaching method. In this case, since the determination is made with respect to the frame received on the upper port 411 side, it is determined whether or not the frame transmitted from the upstream in the network is relayed further downstream from the relay station. Therefore, for example, if the received data is a frame addressed from the master station to the slave station, it is determined that the frame is to be transmitted from the upstream side of the network and is to be relayed further downstream via the lower port. . On the other hand, if the received data is a frame addressed from the slave station to the master station, the master station is located upstream from the relay station, so there is no need to perform relay processing (repeat) downstream via the lower port. It is determined to be a frame.

  When it is determined through such determination processing that the target frame is a frame that needs to be relayed, a repeat start signal is transmitted to the repeat frame generation unit 416. The repeat frame generation unit 416 that has received this repeat start signal transmits the reception data stored in the data buffering unit 413 as repeat transmission frame data to the network via the lower port 417. The lower repeat control unit 415 transmits a repeat start signal to the repeat frame generation unit 416 and also transmits a suppression signal to the upper repeat control unit 421. In the relay station, the frame transmitted by itself may be received by itself. To prevent this, when transmitting frame data from the lower port 417, a signal for suppressing reception at the upper port 411 via the upper repeat control unit 421 is sent to the lower repeat control unit 415. To send.

  When the lower repeat control unit 415 determines that it is not necessary to perform relay, a repeat start signal is not generated and the received data is not relayed.

  Similarly, a case where a frame is transmitted from the lower port 417 side will be described below. The frame (received data) sent to the lower port 417 via the bidirectional serial bus is sent to the start code detector 418. The received data is accumulated in the data buffering unit 419 from the start code detection unit 418 and later sent to the repeat frame generation unit 422. At this time, the received data is sent to the data buffering unit 419, and the received data and the start code detection signal are also sent to the frame type identifying unit 420. Next, when a start code detection signal is sent to the frame type identification unit 420, the type of the frame is identified, and the identification result is sent to the upper repeat control unit 421 as a frame type information signal. The upper repeat control unit 421 determines whether or not to perform further relay processing (repeat) via the upper port 411 according to the frame type defined by the frame type information signal.

  The determination method in the upper repeat control unit 421 is the same as that at the time of reception from the upper port 411 described above, but in this case, since the determination is for the frame received on the lower port 417 side, it has been transmitted from the downstream in the network. It becomes a frame. Therefore, if the received data is a frame addressed from the slave station to the master station, it is determined that the frame is to be transmitted from the downstream side of the network and is to be relayed further upstream via the upper port. On the other hand, if the received data is a frame addressed to the slave station from the master station, the slave station is located downstream from the relay station, so the relay process (repeat) to the master station located upstream via the upper port is It is determined that the frame does not need to be performed.

  When it is determined that it is necessary to perform relaying through such determination processing, a repeat start signal is transmitted to the repeat frame generation unit 422. The repeat frame generation unit 422 that has received this repeat start signal transmits the reception data stored in the data buffering unit 419 to the network via the upper port 411 as repeat transmission frame data. The upper repeat control unit 421 transmits a repeat start signal to the repeat frame generation unit 422 and also transmits a suppression signal to the lower repeat control unit 415. In the relay station, the frame transmitted by itself may be received by itself. To prevent this, when transmitting frame data from the upper port 411, a signal for suppressing reception at the lower port 417 via the lower repeat control unit 415 is sent to the upper repeat control unit 421. To send.

  If the upper repeat control unit 421 determines that it is not necessary to perform relay, a repeat start signal is not generated and received data is not relayed.

  The processing performed at the relay station is shown in the flowchart of FIG. As shown in the figure, the host port side first starts in a standby state waiting for frame reception (step 1501). After receiving the frame, the start code of the received frame is detected (step 1502). When the start code of the frame is detected, header identification (frame type identification) is performed based on the frame identification header included in the frame described above with reference to FIG. 9, and whether or not the frame type is a repeat target frame. Is determined (step 1503). If the target frame is a repeat target frame (step 1503, repeat target frame), a reception / repeat stop signal is transmitted to the lower port (step 1504), and then repeat processing to the lower port is started (step 1505). On the other hand, if the target frame is a non-repeatable frame (step 1503, non-repeatable frame), the process returns to step 1501 and waits for the next received frame.

  Similarly, the lower port side starts in a standby state waiting for frame reception (step 1506). After receiving the frame, the start code of the received frame is detected (step 1507). When the start code of the frame is detected, header identification (frame type identification) is performed based on the frame identification header included in the frame, and it is determined whether or not the frame type is a repeat target frame (step 1508). ). If the target frame is a repeat target frame (step 1508, repeat target frame), a reception / repeat stop signal is transmitted to the upper port (step 1509), and then repeat processing to the upper port is started (step 1510). On the other hand, if the target frame is a non-repeatable frame (step 1508, non-repeatable frame), the process returns to step 1506 and waits for the next received frame.

  With such a configuration, each relay station can determine the type of received frame and relay only frames that need to be relayed. In the above embodiment, the network configuration is described as two relay stations and five slave stations. However, the same effect can be obtained by performing the same processing in different networks.

  In addition, the relay station having such a function is set to distinguish whether to relay or not relay each of the various communication frames, and any of the various communication frames can be changed by changing the setting. It is also possible to switch the result of the determination process of whether the frame is to be relayed or not to be relayed. Similarly, it is also possible to provide a period (time) during which no relay process is performed by setting.

  Furthermore, in the above configuration, the relay operation itself of an arbitrary relay station can be stopped. As a result, an independent network separated by relay stations whose relay operation has been stopped can exist.

  An example of the independent network is shown in FIG. In this figure, the basic configuration is the same as that of FIG. 10 and FIG. 11 described above, so the same reference numerals are given to the same components and the description thereof is omitted. 16 differs from the network configurations of FIGS. 10 and 11 in that a submaster (submaster) station 60 is installed on the network branch line 32. In such a network configuration, by setting so as to stop the relay operation in the relay station 50a on the network branch line 32, it is possible to configure an independent network separated by the relay station 50a in which the relay operation is stopped. Become. More specifically, in the network of FIG. 3, the network branch line 32 divided by the relay station 50a, the slave station 40d, the slave station 40e installed on the network branch line 32, and the newly installed submaster. Station 60 is configured as an independent network. Then, by connecting the sub master station 60 to this independent network, high-speed communication within the independent network becomes possible.

  When this independent network is incorporated into the same network again, a return instruction frame is transmitted from the sub-master station 60 to the relay station 50a. When receiving the return instruction frame, the relay station 50a returns the return status to the master station 30 and restarts the relay operation. This restores the network.

  In the case of the above-described return method, it may take time to return. In this case, it may be set such that the relay operation is stopped only for a predetermined time from the reception of a specific frame at the upper port of the target relay station (the relay station 50a in this example) for which the relay operation is stopped. At the same time, it is possible to set the sub-master 60 to operate only during that period, so that it is possible to suppress the overall frame occupancy rate of the network.

  Next, an operation model of a communication frame in a network to which the present invention is applied will be described with reference to FIGS. FIG. 17 is a system configuration diagram of the network used in the description of the prior art. The case where the present invention is used in the same system configuration will be described below. Needless to say, since the configuration of FIG. 17 has already been described in detail in the description of the prior art, description thereof is omitted here.

  The operation of the master station in the network system having such a configuration will be described with reference to the flowchart shown in FIG. As shown in the figure, the master station transmits a BF (Beacon frame) (step 1101). As described above, this BF is transmitted simultaneously to all slave stations. Subsequently, a trigger frame is transmitted (step 1102). In response to the transmission of the BF and the trigger frame, it is confirmed whether a CN frame is returned from each slave station (step 1103). If a CN frame has been returned (step 1103, YES), the slave join process is performed. As the joining process, a slave information reading process (Step 1104) by StatusRead is performed. This reading process includes reading of the number of relay station passing stages by a CN frame. Then, as another process of the subscription process, a process of writing information to the slave by StatusWrite (step 1105) is performed. This writing process includes time domain writing based on the network configuration obtained by reading the slave information. When these processes are completed, the process returns to Step 1101 again.

  Next, the operation on the slave station side will be described with reference to FIG. Based on the BF from the master station, the frame transmission rate and the number of repeater passing stages are ascertained using the method described above (step 1201). When this grasping process is completed, the state transitions to a state where a trigger frame from the master station can be received (step 1202). Whether or not a trigger frame is received from the master station is confirmed (step 1203). At this time, if the reception of the trigger frame cannot be confirmed (step 1203, NO), the process waits until the trigger frame is received. If the reception of the trigger frame from the master station can be confirmed (step 1203, YES), it is next determined whether or not it is a CN response corresponding node (step 1204). At this time, if the node is not a CN response corresponding node (step 1204, NO), the process returns to 1203 and waits for the next trigger frame. If the node is a CN response corresponding node (step 1204, YES), the CN frame is returned to the master station (step 1205). Subsequently, it waits for the reception of StatusRead from the master station (step 1206 and step 1206, NO). If StatusRead from the master station is received (step 1206, YES), the received StatusRead response is returned to the master station (step 1207). Subsequently, it waits for reception of StatusWrite from the master station (step 1208 and step 1208, NO). When the StatusWrite from the master station is received (step 1208, YES), the state is changed to the subscription state with the parameter of StatusWrite (step 1209).

  FIG. 20 shows an operation model showing the trigger frame transmitted by the master station and the response frames responded by the slave stations in time series at the four observation points A to D shown in FIG. As shown in the figure, at the observation point A, in addition to the trigger frame from the master station, the response frame from each slave station is known, but at the other observation points B, C, and D, Only the trigger frame from the master station and the response frame from the slave station located downstream from each observation point in the network configuration are known, and unnecessary frames are not relayed as in the conventional example shown in FIG. Is clear.

  In this embodiment, each relay station is set to relay the response frame only from the downstream to the upstream, and each response frame passes so that the interval between the response frames can be minimized at the observation point A. It is set to respond quickly by the repeater delay time corresponding to the number of relay stations. With this setting, the interval between the response frames at the observation point A can be minimized, and as shown in FIG. 20, a reduction in repeater delay is realized in each response frame.

The transmission timing of the response frame in each slave station is
Response time of corresponding slave station response frame transmission after receiving trigger frame = Position of response frame of corresponding slave station at observation point A
-Trigger frame arrival delay
-Time until the corresponding slave station response frame arrives at observation point A = position of the corresponding slave station response frame at observation point A
-Repeater delay x number of repeater (relay station) stages to the corresponding slave x 2
It becomes.

At this time, the communication cycle is
Communication cycle =
Trigger frame time + repeater delay x maximum number of repeater stages
+ (Response frame time) x number of slaves.

  Therefore, compared with the conventional example, the communication cycle becomes faster by the amount of “repeater delay × maximum repeater stage number × (2 × number of slaves−1)”.

  When the network having the above configuration is applied, the relay station clearly defines two communication ports on the upper side (master side) and the lower side (slave side), and each communication port corresponds to a role. Need to connect to the network. More specifically, the upper port of the relay station is connected to the upstream side (master side) of the network, and the lower port is connected to the downstream side (slave side) of the network. However, if the upper / lower sides of this port are connected in reverse, a problem will occur.

  The normal connection state and the reverse connection state of the upper port and the lower port in the relay station are shown in FIGS. 21A and 21B, respectively. As shown in FIG. 21A, at the time of normal connection, the upper port of the relay station is connected to the upstream side (master side), and the lower port is connected to the downstream side (slave side). Then, the frame addressed to the master station is received at the lower port of the relay station, and is transmitted from the upper port to the master station via the relay process. On the contrary, the frame addressed to the slave station is received by the upper port of the relay station, and is transmitted from the lower port to the slave station via the relay process.

  On the other hand, as shown in FIG. 5B, at the time of reverse connection, the lower port of the relay station is connected to the upstream side (master side), and the upper port is connected to the downstream side (slave side). Then, the frame addressed to the master station is received by the upper port of the relay station, and is transmitted from the lower port to the master station via the relay process. However, as described above, each relay station has a function of determining whether or not the received communication frame is a relay target frame, and relays only the relay target frame. In such a communication network, the master station is not installed on the downstream side of the network due to its nature. Therefore, the frame addressed to the master station should be received by the lower port of the relay station, and if received by the upper port, it is not identified as the relay target frame.

  Similarly, the frame addressed to the slave station is received at the lower port of the relay station, and is transmitted from the upper port to the slave station via the relay process. Also in this case, the frame addressed to the slave station should be received at the upper port of the relay station, and if received at the lower port, it is not identified as the relay target frame.

  The fact that the communication frame that should be relayed is not identified as the relay target frame because the relay station is reversely connected means that various communication frames from the master station are not relayed by the relay station. It becomes. In such a case, not only the efficiency of the network mentioned above cannot be achieved, but also the serious problem that the network itself does not operate. Therefore, when a relay station is reversely connected, it is important for the operation of the network to enable the relay station to detect the reverse connection state.

  In such a communication network, a master station that plays a role in managing the network is installed in the uppermost stream of the network due to its nature. And the communication frame addressed to each slave station transmitted from the master station should be received at the upper port side at the relay station, and received at the lower port if the relay station is normally connected. impossible. For this reason, for example, as shown in FIG. 21B, when a frame addressed to a slave station is received from a master station at a lower port of the relay station, the relay station is reversely connected. In such a case, a warning or the like can be issued to the user.

  Further, when the reverse connection detection of the relay station described above is detected, the user can automatically switch between the upper port and the lower port within the relay station, so that the user is not aware of the upper port or the lower port of the relay station. Can be operated. FIG. 22 shows a schematic configuration diagram of a relay station provided with an automatic return means for reverse connection that automatically returns to a normal state when reverse connection is detected by the relay station. Here, since the part engaged in the relay process in the relay station has already been described, in FIG. As shown in the figure, selectors 71 and 72 are provided in two connection portions where the relay station connects to the network, respectively, and the upper port is connected to the two selectors 71 and 72 at both ends, and further relayed. Connected to function 70. Similarly, both ends of the lower port are connected to the two selectors 71 and 72 and further connected to the relay function 70. With such a configuration, the upper port and the lower port can be switched by the two selectors 71 and 72 to be connected to the network in the upper part or to the network in the lower part. For example, when the upper port is connected to the network via the selector 71 side, the lower port is connected to the network via the selector 72 side.

  Here, it is assumed that the connection state of the relay station is a state in which the upper port is connected to the network on the selector 71 side and the lower port is connected to the network on the selector 72 side. In this state, when a frame addressed to the slave is received from the master station on the lower port side, that is, the selector 72 side, the relay station recognizes that the relay station is reversely connected. Therefore, if the upper port and the lower port are switched by the switching function of the selectors 71 and 72, the connection state returns to normal.

  Further, with such a configuration, even when reverse connection of the relay station is detected, the relay station is provided with means for automatically returning to the normal state, so that the user can save time for reconnection. In addition, even when the network is connected, it can be incorporated into the network without being aware of the connection state between the upper port and the lower port of the relay station, thereby improving work efficiency.

  As is clear from the above description, according to the present invention, the relay station installed on the network identifies the communication frame to be relayed and does not perform unnecessary frame relay, so that the network efficiency is improved, and the relay station Even if the network is connected in the reverse direction to the network, the reverse connection is detected and automatically returned to the normal state, so that the work efficiency is improved without bothering the user.

It is a block diagram of a PLC system including a communication master station, a communication slave station, and a relay station. It is a hardware block diagram of a communication master station. It is a hardware block diagram of a communication slave station. It is a hardware block diagram of a relay station. It is a frame block diagram of a BEACON frame. It is a schematic diagram of transmission / reception of a frame. It is a process flowchart at the time of BF reception of a relay station. It is a process flowchart at the time of BF reception of a slave station. It is a frame block diagram of a frame. It is a figure explaining frame transmission from a master station to a slave station. It is a figure explaining the frame transmission from a slave station to a master station. It is a figure explaining the network occupation rate of a prior art. It is a figure explaining the network occupation rate in this invention. It is a functional block diagram for demonstrating operation | movement of a relay station. It is a flowchart which shows the process of a relay station. It is a figure explaining the structure of the independent network using a submaster station. FIG. 2 is a system configuration diagram of a network configured with two relay station stages. It is an operation | movement flowchart of a master station. It is an operation | movement flowchart of a slave station. It is a frame operation model (the present invention) in a relay station two-stage configuration. It is a figure explaining the time of normal connection of a relay station, and the time of reverse connection. It is a schematic block diagram of the relay station provided with the automatic return means of reverse connection. It is a frame operation model (conventional example) in a relay station two-stage configuration.

Explanation of symbols

1 PLC
2 Slave station 3 PC
4 relay station 5 terminator 6 field bus 7 I / O device 10 communication master unit 20 CPU unit 30 master station 31 network trunk line 32 network branch line 1
33 Network branch line 2
40a to 40e Slave station 50a, b Relay station 60 Sub master station

Claims (8)

A master station, which is a programmable controller having a communication function, and one or more slave stations, which are I / O terminal devices having a communication function, are connected by a bus type network and are on the bus type network. In a communication system in which a relay station functioning as a repeater is interposed over one or more stages on a path connecting a station and a predetermined slave station,
Various communication frames transmitted by the master station and the slave station include identification information for identifying the type of the frame,
The relay station has means for determining the type of the communication frame based on the identification information of the received communication frame, and performing a relay process only for the communication frame that needs the relay process. .   The communication system according to claim 1, wherein the relay station includes a setting unit that switches between various communication frames to be a communication frame for relay processing or a communication frame for which relay processing is not performed.   The communication system according to claim 1, wherein the relay station includes setting means capable of providing a period during which no relay processing is performed. A master station, which is a programmable controller having a communication function, and one or more slave stations, which are I / O terminal devices having a communication function, are connected by a bus type network and are on the bus type network. In a communication system in which a relay station functioning as a repeater is interposed over one or more stages on a path connecting a station and a predetermined slave station,
Means for identifying the type of communication frame to be received;
Means for determining whether to perform relay processing on the communication frame according to the type of the identified communication frame;
Means for performing relay processing on a communication frame determined to be relayed;
A relay device comprising:   The relay apparatus according to claim 4, further comprising a switching unit that switches a setting between a communication frame for performing the relay process and a communication frame for which the relay process is not performed.   The relay apparatus according to claim 4, wherein the relay apparatus can be set not to perform relay processing for a predetermined period.   The relay device has an upper port connected to the upstream side of the network and a lower port connected to the downstream side, and detects when the upper port and the lower port are connected to the network in reverse. The relay device according to claim 5, wherein In the relay device, each of the upper port and the lower port is connected to the upstream and downstream of the network via two common selectors,
When it is detected that the upper port and the lower port are connected to the network in reverse, the function between the upper port and the lower port can be switched by two selectors. The relay apparatus according to claim 7, wherein the relay apparatus can automatically return to a normal connection state.

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