JP2011239065A - Repeating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a repeating device which is capable of relaying scan transmission data with high communication efficiency and certainty even if transmission cycle lengths of scan transmission between networks which are connected are different.SOLUTION: A repeating device relays scan transmission data transmitted from devices consisting of a network for process control by means of a scan transmission scheme between a plurality of networks which use mutually different communication standards. The repeating device comprises: relay control means for converting scan transmission data received from a first network to data in accordance with a communication standard of a second network; storage means for storing a transmission cycle length of the scan transmission data in the second network; and first transmission control means for transmitting the scan transmission data converted by the relay control means to the second network with the transmission cycle length of the second network and with the scan transmission scheme.

Description

  The present invention relates to a relay device that relays scan transmission data transmitted using a scan transmission method between devices constituting a process control network between a plurality of networks having different communication standards, and in particular, reliable and efficient in communication. The present invention relates to a relay device that relays scan transmission data.

  Specifically, it relays scan transmission between networks in distributed control systems and safety instrumentation systems used for plant operation control and safety assurance in a wide range of fields such as petrochemical, steel, pulp and paper, food, medicine, and electric power. The present invention relates to a relay device.

  Conventionally, in a distributed control system and a safety instrumented system, a plurality of field devices and a plurality of control devices that control these field devices are connected via connection lines and telecommunication lines, and a network such as a LAN (Local Area Network) It transmits and receives measurement data, control data for process control, and the like.

  Here, data communication such as valve operation values and flow meter flow values is performed between the control devices. Such a system is described in, for example, Japanese Patent Application Laid-Open No. 2005-176161.

  Note that field devices include various field devices such as a differential pressure gauge, a flow meter, a thermometer, a monitoring camera, an actuator, and a controller.

  In data sharing used for plant control, in general, control devices, repeaters such as network switches, and field devices (hereinafter collectively referred to as communication stations) are connected to a plurality of control devices inside and outside the network to which the device is connected. In many cases, “scan transmission” is used to send a broadcast notification to a communication station such as a network switch or field device in a cyclic manner.

  Here, the scan transmission is a method in which the control device transmits the information of the own device to a plurality of control devices or communication stations in the network or outside by applying broadcast transmission.

  A plurality of control devices constituting the network each include a memory for storing scan transmission data transmitted by scan transmission, and all control devices perform cyclic transmission of data transmitted from each control device at high speed. The data in the memory is updated to the same content.

  Here, the scan transmission is a one-to-many broadcast notification, and the number of transmissions can be reduced compared with the one-to-many unicast communication, so that the bandwidth can be saved and a control network that requires real-time performance Is an effective communication method.

  For example, a relay apparatus that relays scan transmission between different networks has been invented as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2005-094289).

FIG. 3 is a configuration diagram illustrating an example of a conventional relay device.
In FIG. 3, the relay device 1 is connected to the network N1 and the network N2, transfers the scan transmission data from the network N1 to the network N2, and transfers the scan transmission data from the network N2 to the network N1.

Specifically, the relay apparatus 1 receives the scan transmission data from the network N1 and transmits the scan transmission data from the network N2, and the N1 communication unit 11 stores the scan transmission data from the network N2. A transmission buffer 12, an N2 communication means 13 for receiving scan transmission data from the network N2 and transmitting scan transmission data from the network N1, an N2 transmission buffer 14 for storing scan transmission data from the network N1, Relay control means 15 for converting data of the network N1 (or N2) into a protocol for the network N2 (or N1).
The relay device 1 includes an arithmetic control unit 16 that controls functions of a relay device such as a CPU (Central Processing Unit), and mainly includes functional blocks of the relay control means 15.

  Hereinafter, the networks N1 and N2 have different communication standards (protocols), and due to the difference in design concept and available resources, the transmission cycle of scan transmission is different in each network. The transmission cycle of N1 is higher than that of N2. Is described as short.

  With such a configuration, the relay device 1 performs the following operations (1-1) to (1-4) and (2-1) to (2-4).

When the relay device 1 relays scan transmission data from the network N1 to the network N2, the following operation is performed.
(1-1) The N1 communication unit 11 receives scan transmission data from any of the control devices in the network N1.
(1-2) The arithmetic control unit 16 stores the scan transmission data from the N1 communication unit 11 in the N2 buffer 14.
(1-3) The relay control means 15 reads the scan transmission data from the N2 buffer 14, converts (processes) it into the protocol of the network N2, and outputs it to the N2 communication means 13.
(1-4) The N2 communication means 13 transmits the scan transmission data converted for the protocol of the network N2 to the network N2.
At this time, the transmission cycle of the scan transmission that the relay apparatus 1 transmits to the network N2 is equal to the scan transmission transmission cycle in the network N1.

When the relay device 1 relays scan transmission data from the network N2 to the network N1, the following operation is performed.
(2-1) The N2 communication means 13 receives scan transmission data from any control device in the network N2.
(2-2) The arithmetic control unit 16 stores the scan transmission data from the N2 communication means 13 in the N1 buffer 12.
(2-3) The relay control means 15 reads the scan transmission data from the N1 buffer 12, converts (processes) it into the protocol of the network N1 and outputs it to the N1 communication means 11.
(2-4) The communication means 11 for N1 transmits the scan transmission data converted for the protocol of the network N2 to the network N1.
At this time, the transmission cycle of the scan transmission that the relay apparatus 1 transmits to the network N1 is equal to the scan transmission transmission cycle in the network N2.

  As a result, the conventional relay device can relay scan transmission between two networks having different protocols.

  As a document describing such a conventional relay device, there is Patent Document 1 or the like.

JP 2005-094289 A

  However, when relaying from a network with a short transmission cycle to a network with a long transmission cycle, the conventional relay device relays scan transmission data that is unnecessary for the relay destination network. There was a problem of doing. For this reason, there has been a problem that unnecessary scan transmission data increases the reception load of a communication station (control device, network switch, etc.) in the relay destination network, thereby reducing the real-time performance of communication.

  In addition, when a relay device relays scan transmission from a network with a long transmission cycle to a network with a short transmission cycle, if the scan transmission data is lost due to a transient error, the data is updated until the next relay timing. Since this is not performed, there is a problem in that data may not be updated within the delay time assumed by the control device or communication station (control device, network switch, etc.) of the relay destination network. For this reason, there is a problem that the latest data is not used for process control and optimal control cannot be executed.

  The present invention solves the above-described problems, and an object of the present invention is to relay scan transmission data reliably and efficiently even if the transmission cycle of scan transmission differs between connected networks. It is to realize a possible relay device.

In order to achieve such an object, the invention described in claim 1 of the present invention is:
In a relay device that relays scan transmission data transmitted using a scan transmission method between devices constituting a process control network between a plurality of networks having different communication standards,
Relay control means for converting scan transmission data received from the first network into data conforming to the communication standard of the second network;
Storage means for storing a transmission period of the scan transmission data in the second network;
First transmission control means for transmitting scan transmission data converted by the relay control means to the second network using a scan transmission method at a transmission period in scan transmission of the second network is provided. Characteristic relay device.

The invention according to claim 2 is the relay apparatus according to claim 1,
The storage means stores a transmission cycle of the scan transmission data in the first network;
The relay control means converts the scan transmission data received from the second network into data conforming to the communication standard of the first network;
Second transmission control means for transmitting scan transmission data received from the second network and converted by the relay control means to the first network using a scan transmission method at a transmission cycle of the first network. Is provided.

The invention according to claim 3 is the relay apparatus according to claim 2,
The first transmission control means transmits the scan transmission data to the second network at a transmission period of the second network, and the second transmission control means transmits the scan transmission data to the first network. Period adjustment means for transmitting to the first network at a transmission period is provided.

Invention of Claim 4 is the relay apparatus in any one of Claims 1-3,
Storing in advance a first data table storing identifiers of devices connected to the first network and a second data table storing identifiers of devices connected to the second network;
When this identifier and the identifier of the transmission source of the scan transmission data received from the first network or the second network do not match the identifier in the second data table or the first data table, the scan transmission data is relayed. A communication station information management means is provided.

Invention of Claim 5 is the relay apparatus in any one of Claims 1-4,
Timing adjustment means for causing the second transmission control means or the first transmission control means to transmit the scan transmission data at a timing different from each timing of the scan transmission of the device connected to the first network or the second network. It is provided with.

A sixth aspect of the present invention is the relay device according to any one of the first to fifth aspects,
Scan transmission in which two or more scan transmission data received from a device connected to the first network or the second network are combined and transmitted to the second network or the first network using a scan transmission method A data combination means is provided.

  According to the relay device of the present invention, the relay control means for converting the scan transmission data received from the first network into the data conforming to the communication standard of the second network, and the transmission of the scan transmission data in the second network A storage unit for storing a cycle; and a first transmission control unit for transmitting the scan transmission data converted by the relay control unit to the second network using the scan transmission method in the transmission cycle of the second network. Thus, even if the transmission cycle of scan transmission differs between connected networks, the relay device is effective in absorbing the difference and relaying scan transmission data with high communication efficiency.

Further, according to the relay device according to the present invention, the following effects A, B, and C can be expected by adopting the above-described configuration.
A: When a relay device relays scan transmission from a network with a short transmission cycle to a network with a long transmission cycle, frames unnecessary for the relay destination network (scan transmission data) are not relayed to prevent the use of extra bandwidth. Can do.
B: Since only necessary frames (scan transmission data) are relayed, an increase in reception load of a communication station (control device, network switch, etc.) in the relay destination network is minimized, and deterioration of real-time performance is prevented. it can.
C: When a relay device relays scan transmission from a network with a long transmission cycle to a network with a short transmission cycle, even if the scan transmission data is lost due to a transient error, the communication station (control device, network switch, etc.) of the relay destination network This is effective in that data is updated within the delay time that is assumed by.

  Further, according to the present invention, only when the scan transmission data received by the communication station information management means is normal, it is transmitted to the relay destination network, and when it is abnormal data, it is discarded without being transmitted to the relay destination network. As a result, abnormal data is transmitted to the relay destination network, so that it is possible to prevent the use of an extra communication band and the consumption of processor power and memory of the communication station. Therefore, this is effective in that the scan transmission data can be relayed efficiently and reliably.

  In addition, according to the present invention, the timing adjustment means can preliminarily allocate a timing that can be transmitted to all communication stations including the own device (relay device 2), thereby avoiding a situation where communication rushes at one time, The real-time property of the network can be improved. Therefore, this is effective in that the scan transmission data can be relayed efficiently and reliably.

It is a block diagram of one Example of the relay apparatus based on this invention. It is a block diagram of the other Example of the relay apparatus which concerns on this invention. It is the block diagram which showed an example of the conventional relay apparatus.

<First embodiment>
FIG. 1 is a configuration diagram of an embodiment of a relay device according to the present invention, and parts common to FIG.
The main difference from FIG. 3 is that, in FIG. 1, it has a storage means for storing each transmission cycle of each scan transmission data in each network, and the relay control means converts it into a data format conforming to the communication standard of the second network. The difference is that a first transmission control unit is provided for transmitting the scanned transmission data to the second network using the scan transmission method at the transmission cycle of the second network.

(Description of configuration)
In FIG. 1, a relay apparatus 2 according to the present invention is connected to a network N1 which is an example of a first network and a network N2 which is an example of a second network, and scan transmission data from the network N1 is transmitted to the network N2. The scan transmission data from the network N2 is transferred to the network N1.

  The networks N1 and N2 are configured by connecting a plurality of field devices and a plurality of control devices that control these field devices via connection lines and telecommunication lines.

In the networks N1 and N2, transmission / reception of measurement data and control data for process control by field devices and control devices is performed via a communication station such as a network switch.
In addition, a controller connected to the networks N1 and N2, a repeater such as a network switch, and a field device (hereinafter collectively referred to as a communication station) include a plurality of communication stations inside and outside the network as data sharing used for plant control. Executes a scan transmission that sends a broadcast notification to the user.

  The relay apparatus 2 receives scan transmission data (hereinafter referred to as first scan transmission data) from the network N1, and scans the network N1 for scan transmission data (hereinafter referred to as second scan transmission data) from the network N2. Stores N1 communication means 21 which is an example of first transmission control means for transmitting based on the scan transmission method in a data format conforming to the communication standard of network N1 in the transmission data transmission cycle, and scan transmission data from network N2. The N1 transmission buffer 22 as an example of the first buffer to be received and the second scan transmission data are received, and the first scan transmission data conforms to the communication standard of the network N2 at the transmission cycle of the scan transmission data of the network N2. Second transmission control for transmitting data based on scan transmission method And N2 for the communication unit 23 is an example of a stage, a second N2 transmission buffer 24 which is an example of a buffer for storing scanned data transmitted from the network N1, provided.

  Further, the relay device 2 includes a relay control unit 25 that converts data of the network N1 (or N2) into a protocol for the network N2 (or N1), and each transmission cycle (hereinafter referred to as “scan transmission data”) in the network N1 and the network N2. Storage means 26 for storing the first transmission cycle and the second transmission cycle), and the N1 communication means 21 causes the second scan transmission data to be transmitted to the network N1 in the first transmission cycle, thereby communicating the N2 communication means. 23 also includes period adjusting means 27 for transmitting the first scan transmission data to the network N2 in the second transmission period.

  In addition, the relay device includes a calculation control unit 29 such as a CPU (Central Processing Unit), and mainly includes functional blocks of a relay control unit 25 and a cycle adjustment unit 27. Each of these means may be composed of independent devices connected to each other by a bus.

  Specifically, the arithmetic control unit 29 starts mainly the OS stored in the storage unit 26, reads out and executes the program stored in the storage unit on the OS, thereby mainly performing the relay control unit. 25, the functions such as the period adjusting means 27 are controlled in an integrated manner, and the entire relay apparatus is controlled to relay scan transmission between two networks having different protocols.

  The storage means 26 is a hard disk, a RAM (Random Access Memory), a ROM (Read Only Memory), or the like. Protocol information necessary for processing each transmission cycle and scan transmission data so as to conform to each network protocol, and Stores network path information indicating a path to a transmission destination when relaying scan transmission data between the networks N1 and N2, an OS for operating as a relay apparatus, a program, an application, and the like.

The relay control unit 25 converts the scan transmission data from the network N2 stored in the N1 transmission buffer 22 into data conforming to the protocol for the network N1 based on the protocol information stored in the storage unit 26. .
Further, the relay control means 25 converts the scan transmission data from the network N1 stored in the N2 transmission buffer 24 into data conforming to the protocol for the network N2 based on the protocol information stored in the storage means 26. .

Although not particularly illustrated, the relay device 2 sets the cycle in which the N1 communication unit 21 and the N2 communication unit 23 transmit the scan transmission data to any one of the transmission cycles stored in the storage unit 26. There is also display control means for displaying a display screen capable of setting the above on display means such as a monitor.
Here, the transmission cycle for relaying the scan transmission data to the network N1 and the network N2 is set in advance by the user via an input means, a display screen, etc. (not shown).

  Hereinafter, the networks N1 and N2 have different communication standards (protocols), and due to differences in design philosophy, available resources, etc., the transmission cycle of scan transmission differs in each network. N1 transmits more than N2 The description will be made assuming that the cycle is short.

(Description of operation)
With such a configuration, the relay device 2 performs the following operations (3-1) to (3-5) and (4-1) to (4-5).

When the relay device 1 relays scan transmission data from the network N1 to the network N2, the following operation is performed.
(3-1) The N1 communication means 21 receives scan transmission data from any control device in the network N1.
(3-2) The arithmetic control unit 29 stores the scan transmission data from the N1 communication means 21 in the N2 buffer 24.
(3-3) The cycle adjusting unit 27 reads out the second transmission cycle in which the scan transmission data is transmitted in the network N2 from the storage unit 26, and sends the relay control unit 25 a transmission timing that matches the second transmission cycle. Is transmitted to the relay control means 25 and the N2 communication means 23.
(3-4) Based on the received timing information, the relay control means 25 reads the scan transmission data from the N2 buffer 24 a predetermined time before the timing, and converts (processes) it into the protocol of the network N2. And output to the communication means 23 for N2.
(3-5) The N2 communication unit 23 transmits the scan transmission data converted for the protocol of the network N2 to the network N2 at a timing that matches the second transmission cycle.

  For this reason, the transmission cycle of scan transmission in which the relay device 2 transmits the scan transmission data received from the network N1 to the network N2 is equal to the scan transmission transmission cycle in the network N2.

When the relay device 1 relays scan transmission data from the network N2 to the network N1, the following operation is performed.
(4-1) The N2 communication means 23 receives scan transmission data from any control device in the network N2.
(4-2) The arithmetic control unit 29 stores the scan transmission data from the N2 communication means 23 in the N1 buffer 22.
(4-3) The cycle adjusting unit 27 reads out the first transmission cycle in which the scan transmission data is transmitted in the network N1 from the storage unit 26, and sends the relay control unit 25 a transmission timing that matches the first transmission cycle. Is transmitted to the relay control means 25 and the communication means 21 for N1.
(4-4) Based on the received timing information, the relay control means 25 reads the scan transmission data from the N1 buffer 22 by a predetermined time before the timing, and converts (processes) it into the protocol of the network N1. And output to the communication means 21 for N1.
(4-5) The N1 communication means 21 transmits the scan transmission data converted for the protocol of the network N2 to the network N1 at a timing that matches the first transmission cycle.

  For this reason, the transmission cycle of the scan transmission in which the relay device 2 transmits the scan transmission data received from the network N2 to the network N1 is equal to the scan transmission transmission cycle in the network N1.

  As a result, the relay apparatus according to the present invention includes a relay control unit that converts the scan transmission data received from the first network into data conforming to the communication standard of the second network, and the scan transmission data of the second network. Storage means for storing the transmission cycle, and first transmission control means for transmitting the scan transmission data converted by the relay control means to the second network using the scan transmission method at the transmission cycle of the second network. Therefore, even if the transmission cycle of scan transmission differs between connected networks, it is effective in that the scan transmission data can be relayed efficiently and reliably.

Further, the relay device according to the present invention has the above-described configuration, so that when the transmission cycle of scan transmission is different between two networks having different protocols to which the relay device is connected, the relay device absorbs the difference. In addition, it is possible to relay scan transmission at a period appropriate for each network.
As a result, the following effects A, B, and C can be expected.
A: When a relay device relays scan transmission from a network with a short transmission cycle to a network with a long transmission cycle, frames unnecessary for the relay destination network (scan transmission data) are not relayed to prevent the use of extra bandwidth. Can do.
B: Since only necessary frames (scan transmission data) are relayed, an increase in reception load of a communication station (control device, network switch, etc.) in the relay destination network is minimized, and deterioration of real-time performance is prevented. it can.
C: When a relay device relays scan transmission from a network with a long transmission cycle to a network with a short transmission cycle, even if the scan transmission data is lost due to a transient error, the communication station (control device, network switch, etc.) of the relay destination network This is effective in that data is updated within the delay time that is assumed by.

Note that the relay apparatus according to the present invention is not limited to the transmission period set by the user, and the transmission period in the scan transmission for relaying to two connected networks is preset in the relay apparatus 2. It may be (incorporated).
In this case, it is effective in that the risk caused by the user's engineering error can be reduced.

<Second embodiment>
In addition to the configuration described in the first embodiment, the relay apparatus according to the present invention may include a communication station information management unit that manages addresses of communication stations existing in a connected network. Hereinafter, the configuration will be specifically described with reference to FIG.

  FIG. 2 is a configuration diagram of another embodiment of the relay device according to the present invention, and the configuration in the second to fifth embodiments will be described. In FIG. 2, the same reference numerals are given to the parts common to FIG.

  2, in the relay device 2 according to the present invention, the storage means 26 stores an identifier such as a network address of a communication station (control device, network switch, field device, etc.) connected to the connected network N1. And a second data table in which identifiers such as network addresses of communication stations connected to the network N2 are stored.

  Further, the relay device 2 is a function block or the like provided in the arithmetic control unit 29, based on each data table stored in the storage unit 26, and a transmission source communication station (control device) of scan transmission data received from the network N1 or the network N2. The communication station information management means 30 relays the scan transmission data when the identifier does not match the identifier in the second data table or the first data table, and discards it as abnormal data when they match.

With such a configuration, the relay device 2 performs the following operation when relaying scan transmission.
Hereinafter, a case where the scan transmission data from the network N1 is relayed to the network N2 will be described as an example. The case where the scan transmission data from the network N2 is relayed to the network N1 is almost the same as this, and the description thereof is omitted.

The communication station information management means 30 extracts the identifier (address, etc.) of the transmission source communication station based on the scan transmission data from any control device in the network N1 received by the N1 communication means 21.
Further, the communication station information management means 30 compares the extracted identifier (source address) with the identifier in the second data table.
Then, when the communication station information management means 30 determines that there is a mismatch as a result of the comparison (in other words, when the transmission source communication station does not overlap with the network N2 as the relay destination), the relay device 2 Assuming that the scan transmission data is normal data, the relay control means 25 and the cycle adjustment means 27 relay the scan transmission data to the relay destination network N2.
On the other hand, when the communication station information management unit 30 determines that the two match as a result of the comparison (that is, when the transmission source communication station is duplicated in the relay destination network), the relay device 2 performs the scan. Discard transmission data as abnormal data.

  As a result, the relay apparatus of the present invention transmits to the relay destination network only when the scan transmission data received by the communication station information management means is normal, and transmits to the relay destination network when the data is abnormal. By discarding them without error, it is possible to prevent abnormal data from being transmitted to the relay destination network and use of an extra communication band, processor power of the communication station, and memory consumption. Therefore, this is effective in that the scan transmission data can be relayed efficiently and reliably.

<Third embodiment>
In addition to the configuration described in the first embodiment or the second embodiment, the relay device according to the present invention is a device connected to the network N1 or the network N2, and each timing of scan transmission of the communication station. A transmission timing adjustment unit that transmits scan transmission data at different timings and a time synchronization unit that performs time synchronization with a communication station of the network N1 or N2 may be provided.

Specifically, the relay device 2 according to the present invention is configured such that the functional block and the like included in the arithmetic control unit 29 communicates for N2 at different timings from the scan transmission timings of the communication stations connected to the network N1 or the network N2. A timing adjusting unit 31 for transmitting the scan transmission data to the unit 23 or the N1 communication unit 21 and a time synchronization unit 32 for performing time synchronization with the communication station of the network N1 or N2.
The storage unit 26 stores each timing chart of scan transmission in a communication station connected to the network N1 or the network N2.

With such a configuration, the relay device 2 performs the following operation when relaying scan transmission.
Hereinafter, a case where the scan transmission data from the network N1 is relayed to the network N2 will be described as an example. The case where the scan transmission data from the network N2 is relayed to the network N1 is almost the same as this, and the description thereof is omitted.

  The time synchronization means 32 performs time synchronization by transmitting and receiving control data for performing time synchronization with the communication station of the network N1 or N2.

  The timing adjustment unit 31 assigns the timing at which the relay device 2 transmits the scan transmission data based on the timing chart of the storage unit 26. For example, the timing adjustment unit 31 extracts and assigns the timing at which the relay apparatus 2 can transmit the scan transmission data, avoiding the timing at which the communication station of the network N1 or the network N2 transmits the scan transmission data.

  The cycle adjusting unit 27 reads the first transmission cycle in which the scan transmission data is transmitted in the network N1 from the storage unit 26, and performs the first transmission to the relay control unit 25 at the timing assigned by the timing adjusting unit 31. Timing information indicating the transmission timing matching the cycle is transmitted to the relay control means 25 and the N1 communication means 21.

Based on the received timing information, the relay control means 25 reads the scan transmission data from the N1 buffer 22 by a predetermined time before the timing, converts it into a protocol for the network N1, and converts it to N1. To the communication means 21.
The N1 communication unit 21 transmits the scan transmission data converted for the protocol of the network N2 to the network N1 at the timing assigned by the timing adjustment unit 31 and the timing that matches the first transmission cycle.

  As a result, the relay apparatus of the present invention avoids a situation in which communication rushes at a time by the timing adjusting means assigning in advance timings that can be transmitted to all communication stations including the own apparatus (relay apparatus 2). And real-time performance of the network can be improved. Therefore, this is effective in that the scan transmission data can be relayed efficiently and reliably.

<Fourth embodiment>
In addition to the configuration described in any of the first to third embodiments, the relay device according to the present invention receives scan transmission data received from a communication station connected to the network N1 or the network N2. It may be provided with scan transmission data combining means for combining two or more and relaying them using a scan transmission method.

  Specifically, the relay device 2 according to the present invention combines two or more scan transmission data received from a control device or a communication station connected to the network N1 or the network N2 as a functional block or the like included in the arithmetic control unit 29. Then, the scan transmission data combining means 33 for transmitting to the network N1 or the network N2 using the scan transmission method is provided.

With such a configuration, the relay device 2 performs the following operation when relaying scan transmission.
Hereinafter, a case where the scan transmission data from the network N1 is relayed to the network N2 will be described as an example. The case where the scan transmission data from the network N2 is relayed to the network N1 is almost the same as this, and the description thereof is omitted.

The relay device 2 combines (combines) a plurality of scan transmission data in the order stored in the N1 transmission buffer 22 at a timing when the scan transmission data combining unit 33 relays the scan transmission to the network N1. , One scan transmission data (frame) is generated.
At this time, the scan transmission data combining unit 33 generates the combined scan transmission data (frame) having a frame length shorter than a predetermined maximum frame length.

  The relay control unit 25 converts (processes) data including a plurality of scan transmission data combined by the scan transmission data combining unit 33 into a protocol of the network N2, and outputs the converted data to the N2 communication unit 23.

  The N2 communication unit 23 transmits combined data composed of a plurality of scan transmission data combined by the scan transmission data combining unit 33 to the network N1 at a timing that matches the first transmission cycle.

  In this embodiment, when all communication stations existing in the relay destination network receive the combined data (frame) processed by the relay device, the data is divided and the contents of the original scan transmission data (frame) are divided. Has the function of interpreting

  As a result, the relay apparatus of the present invention combines a plurality of scan transmission data in the order stored in the N1 transmission buffer 22 when the scan transmission data combining means 33 relays the scan transmission to the network N1. (Combined) and generating as one scan transmission data (frame), the number of communication frames can be reduced.

  Further, as in the present invention, the scan transmission data combining means 33 combines a plurality of scan transmission data and transmits it as one scan transmission data, so that one scan transmission data having a long communication frame length and the frame length are combined. If there are multiple (multiple) short scan transmission data and the total data size is the same, the time required to read multiple scan transmission data one by one in the network system on the receiving side is reduced, and performance is improved. It is effective in that it can be improved.

<Fifth embodiment>
In addition to the configuration described in any of the first to fourth embodiments, the relay apparatus according to the present invention measures the transmission period of the scan transmission of the networks N1 and N2 and stores it in the storage unit 26. It may be provided with a transmission cycle measuring means.

  Specifically, the relay device 2 according to the present invention receives scan transmission data from the network N1 or N2 connected for a predetermined time as a functional block provided in the arithmetic control unit 29, and the time and A transmission interval of the scan transmission in each of the networks N1 and N2 is measured by calculating a reception interval from the number of receptions (for example, by calculating an average value), and transmission in which each transmission cycle is stored in the storage unit 26 Period measurement means 34 is provided.

  As a result, in the relay device according to the present embodiment, the transmission cycle measuring unit 34 receives the scan transmission data for a predetermined time, and the scan transmission transmission cycle in each network is determined from the time and the number of times received. By calculating, as shown in the first embodiment, scanning with an appropriate transmission cycle for the connected network without the risk of engineering errors that may occur when the user sets the transmission cycle The transmission can be relayed.

2 relay device 21 N1 communication means (first transmission control means)
23 N2 communication means (second transmission control means)
25 relay control means 26 storage means 27 period adjustment means 30 communication station information management means 31 timing adjustment means 33 scan transmission data combining means 34 transmission period measurement means

Claims (6)

In a relay device that relays scan transmission data transmitted using a scan transmission method between devices constituting a process control network between a plurality of networks having different communication standards,
Relay control means for converting scan transmission data received from the first network into data conforming to the communication standard of the second network;
Storage means for storing a transmission period of the scan transmission data in the second network;
First transmission control means for transmitting scan transmission data converted by the relay control means to the second network using a scan transmission method at a transmission period in scan transmission of the second network is provided. Characteristic relay device. The storage means stores a transmission cycle of the scan transmission data in the first network;
The relay control means converts the scan transmission data received from the second network into data conforming to the communication standard of the first network;
Scan transmission data received from the second network and converted by the relay control means is transmitted to the first network using a scan transmission method at a transmission period in the scan transmission of the first network. The relay apparatus according to claim 1, further comprising a transmission control unit.   The first transmission control means transmits the scan transmission data to the second network at a transmission period of the second network, and the second transmission control means transmits the scan transmission data to the first network. The relay apparatus according to claim 2, further comprising period adjusting means for transmitting to the first network at a transmission period. Storing in advance a first data table storing identifiers of devices connected to the first network and a second data table storing identifiers of devices connected to the second network;
When this identifier and the identifier of the transmission source of the scan transmission data received from the first network or the second network do not match the identifier in the second data table or the first data table, the scan transmission data is relayed. The relay apparatus according to claim 1, further comprising communication station information management means.   Timing adjustment means for causing the second transmission control means or the first transmission control means to transmit the scan transmission data at a timing different from each timing of the scan transmission of the device connected to the first network or the second network. The relay device according to claim 1, comprising:   Scan transmission in which two or more scan transmission data received from a device connected to the first network or the second network are combined and transmitted to the second network or the first network using a scan transmission method 6. The relay apparatus according to claim 1, further comprising a data combining unit.

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