JP7277206B2 - Communication control device and method - Google Patents

Description

The present invention relates to a communication control device and method.

For example, in some cases, a control system is used for monitoring control of each facility attached to a building and control of a plant, and a device management device is used (see Patent Document 1). In a control system, control is performed by exchanging signals between field devices such as process devices and various sensors installed on-site, which are connected via a network such as a fieldbus.

In addition, since many field devices are subject to control in this type of control, the control system is divided into blocks, each block is provided with a controller that performs control, and multiple controllers are used to perform distributed control. I have to. For example, a controller provided for each block is connected to the control device, and a plurality of field devices are connected to each of the plurality of controllers. A plurality of controllers are connected to the control device via a network, and a plurality of field devices are connected to each controller.

The connection between the controller and the field device generally uses serial communication with the controller as the master node and the field device as the slave node. Protocols that implement this type of serial communication include, for example, "Modbus (registered trademark)." In this kind of serial communication protocol, only the master node can issue a request, which includes the station address of the slave node receiving the request and the data address to be processed. Only the slave node whose station address is included in the request will execute the request, and other slave nodes will do nothing upon receiving this request.

In the control system described above, a compact setting device that is excellent in portability and portability is used when performing maintenance and inspection of the field device at the site where the field device is installed. In the field device maintenance/inspection using this setting device, the setting device is set as a master node and connected to the network to which the field device to be maintained/inspected is connected. However, in this network, the number of master nodes is limited to one, so in order to directly connect the setting device to the network, the operation of the controller must be stopped and the control must be interrupted. In addition, wiring is required to connect to the network, which impairs the portability and portability of small setting devices.

On the other hand, a relay device having a wireless communication function is connected to the above-mentioned network, the setting device and the relay device are connected by wireless communication, and a request is sent from the setting device serving as a master node to the target field device. A transmission technique has been proposed (see Patent Document 1). According to this technology, it is possible to maintain and inspect field devices using setting devices without interrupting control by the controller.

JP 2017-098762 A

By the way, in the control system described above, a request with a large amount of data composed of a plurality of data addresses to be processed is transmitted from the controller or the setting device. For this reason, the request communication from the controller may be delayed due to the request communication from the setting device during maintenance/inspection, which is a problem. If the number of field devices to be controlled increases and requests are being communicated all the time, the above-described problems will become more pronounced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to enable maintenance and inspection to be performed without greatly affecting control.

A communication control apparatus according to the present invention includes a communication unit configured to receive a first request transmitted from a first master device via a wired network to a slave device as a destination, and a second master device connected by wireless communication. a wireless communication unit configured to receive a second request transmitted from a device to a slave device as a destination; and a relay control unit configured to transmit the first request to the slave device with priority over the second request. Prepare.

In one configuration example of the communication control device, the relay control unit divides the second request for each data address and transmits the second request to the slave device, thereby giving priority to transmission of the first request.

In one configuration example of the communication control device, the relay control unit prioritizes transmission of the first request by reducing the frequency of transmission of the second request.

In one configuration example of the communication control device, the relay control unit sets the transmission cycle of the second request to be twice or more the transmission cycle of the first request.

Further, a communication control method according to the present invention includes: a first step of accepting a first request transmitted from a first master device via a wired network with a slave device as a destination; The method includes a second step of receiving a second request transmitted with the slave device as a destination, and a third step of transmitting the first request to the slave device with priority over the second request.

In one configuration example of the communication control method, the third step divides the second request for each data address and transmits the second request to the slave device, thereby giving priority to the transmission of the first request.

In one configuration example of the above communication control method, the third step prioritizes transmission of the first request by reducing the frequency of transmission of the second request.

In one configuration example of the above communication control method, the third step sets the transmission cycle of the second request to be twice or more the transmission cycle of the first request.

As described above, according to the present invention, the first request transmitted from the first main device via the wired network is prioritized over the second request transmitted from the second main device connected by wireless communication. Since the information is sent to the slave device as a result, maintenance and inspection can be performed without greatly affecting the control.

FIG. 1 is a configuration diagram showing the configuration of communication control apparatus 100 according to an embodiment of the present invention. FIG. 2 is a flow chart for explaining the communication control method according to the embodiment of the invention. FIG. 3 is a flow chart for explaining an operation example (communication control method) of the communication control device 100 according to the first embodiment of the present invention. FIG. 4 is a flow chart for explaining an operation example (communication control method) of the communication control apparatus 100 according to the second embodiment of the present invention. FIG. 5 is a configuration diagram showing the hardware configuration of the communication control device according to the present invention.

A communication control apparatus 100 according to an embodiment of the present invention will be described below with reference to FIG. The communication control device 100 includes a communication section 101 , a wireless communication section 102 and a relay control section 103 .

The communication unit 101 receives a first request transmitted from the first master device 131 via the wired network 151 with the slave device 132 as the destination. The wired network 151 is, for example, a serial network based on "Modbus", the first master device 131 is a master node, and the slave device 132 is a slave node. A plurality of slave devices 132 can be connected to one first master device 131 . The first master device 131 is, for example, a controller, and the slave device 132 is a field device. The controller and field devices constitute a control system for controlling the controlled object.

The wireless communication unit 102 receives a second request transmitted from the second master device 133 connected by wireless communication with the slave device 132 as the destination. The wireless communication unit 102 realizes wireless communication by, for example, the well-known “Bluetooth (registered trademark)” or “ZigBee (registered trademark)”. Also, the wireless communication unit 102 can be configured to realize wireless communication by “Wi-Fi (registered trademark)”. The wireless communication unit 102 also converts the second request into the protocol of the wired network 151, and converts the response to the second request sent from the slave device 132 to the second main device 133 into the protocol of wireless communication. The second main device 133 is, for example, a small setting device for performing maintenance and inspection of field devices.

The relay control unit 103 transmits (relays) the received first request and second request to the slave device 132 . The relay control unit 103 transmits the first request to the slave device 132 with priority over the second request. Therefore, maintenance and inspection of the slave device 132 using the second master device 133 can be performed without greatly affecting the control operation by the first master device 131 and slave device 132 .

Next, the communication control method according to the embodiment of the present invention will be explained using the flowchart of FIG. First, in a first step S101, the communication unit 101 receives a first request transmitted from the first master device 131 via the wired network 151 to the slave device 132 as a destination. Next, in a second step S102, the wireless communication unit 102 receives a second request transmitted from the second master device 133 connected by wireless communication with the slave device 132 as the destination. Next, in a third step S103, the relay control unit 103 transmits the first request to the slave device 132 prior to the second request.

Hereinafter, it will be described in more detail using examples.

[Example 1]
First, Example 1 will be described with reference to FIG. In the first embodiment, in step S<b>111 , the communication unit 101 receives a first request addressed to the slave device 132 from the first master device 131 connected via the wired network 151 . For example, the communication unit 101 has a temporary storage unit (not shown). When the first request addressed to the slave device 132 is received from the first master device 131, it is stored in the temporary storage unit.

Next, in step S112, the wireless communication unit 102 receives a second request transmitted from the second master device 133 connected by wireless communication with the slave device 132 as the destination. For example, the wireless communication unit 102 has a temporary storage unit (not shown). When the second request addressed to the slave device 132 is received from the second master device 133, it is stored in the temporary storage unit.

Next, in step S113, the communication unit 101 determines whether or not the first request is received. The communication unit 101 determines that the first request is accepted based on the fact that the first request is stored in the temporary storage unit of the communication unit 101 .

When communication unit 101 determines acceptance of the first request (Yes in step S113), in step S114, relay control unit 103 retrieves the first request from the temporary storage unit of communication unit 101 and stores the first request in the slave device. 132 and returns to step S111.

If the communication unit 101 does not determine that the first request has been accepted (no in step S113), in step S115, the wireless communication unit 102 transmits the signal from the second master device 133, which is connected by wireless communication, to the slave device 132. It is determined whether or not the second request transmitted with the destination of is accepted. The wireless communication unit 102 determines that the second request is accepted based on the fact that the second request is stored in the temporary storage unit of the wireless communication unit 102 .

If the first request has not been received and the wireless communication unit 102 determines that the second request has been received (Yes in step S115), the relay control unit 103 causes the temporary storage unit of the wireless communication unit 102 to Among the second requests stored in , a second request composed of a plurality of data addresses to be processed is taken out from the temporary storage unit and divided for each data address. A second request composed of the divided single data addresses is stored in the temporary memory. Through the process of step S116, the second request saved in the temporary storage unit is only the second request composed of the single data address. Next, in step S114, relay control section 103 extracts one second request held in the temporary storage section, transmits it to slave device 132, and returns to step S111.

After returning to step S111, if the first request has been accepted, the first request is transmitted to the slave device 132 regardless of whether or not the second request has been accepted. Even if there is a second request received earlier, the first request is sent first and has priority.

[Example 2]
Next, Example 2 will be described with reference to FIG. In the second embodiment, in step S<b>201 , the communication unit 101 receives a first request addressed to the slave device 132 from the first master device 131 connected via the wired network 151 . For example, the communication unit 101 has a temporary storage unit (not shown). When the first request addressed to the slave device 132 is received from the first master device 131, it is stored in the temporary storage unit.

Next, in step S202, the wireless communication unit 102 receives a second request transmitted from the second master device 133 connected by wireless communication with the slave device 132 as the destination. For example, the wireless communication unit 102 has a temporary storage unit (not shown). When the second request addressed to the slave device 132 is received from the second master device 133, it is stored in the temporary storage unit.

Next, in step S203, it is determined whether or not the wireless communication unit 102 has received a second request transmitted from the second master device 133 connected by wireless communication with the slave device 132 as the destination. The wireless communication unit 102 determines that the second request is accepted based on the fact that the second request is stored in the temporary storage unit of the wireless communication unit 102 .

When the wireless communication unit 102 determines that the second request has been accepted (Yes in step S203), in step S204, the relay control unit 103 sets the frequency of transmission of the first request to be less than the frequency of transmission of the first request. First, determine whether the second request can be sent. For example, the relay control unit 103 sets a transmission condition such that the period of transmission of the second request is twice or more the period of transmission of the first request. It is determined whether or not the second request transmitted from the second master device 133 connected by wireless communication with the slave device 132 as the destination is accepted. For example, the wireless communication unit 102 has a temporary storage unit (not shown). When the second request addressed to the slave device 132 is received from the second master device 133, it is stored in the temporary storage unit. The wireless communication unit 102 determines that the second request has been accepted by storing the second request in the temporary storage unit.

When relay control unit 103 determines that the second request can be transmitted (yes in step S204), relay control unit 103 transmits the second request stored in the temporary storage unit of wireless communication unit 102 in step S205. Send to device 132 .

If the wireless communication unit 102 does not determine that the second request has been accepted (no in step S203), in step S206, the communication unit 101 causes the first main device 131 connected via the wired network 151 to It is determined whether or not the first request transmitted with the slave device 132 as the destination is accepted. When communication unit 101 determines that the first request has been accepted (yes in step S206), relay control unit 103 transmits the first request to slave device 132 in step S205. On the other hand, if the communication unit 101 does not determine acceptance of the first request (no in step S206), the process returns to step S201.

Further, when the relay control unit 103 determines that the second request cannot be transmitted after receiving the second request (no in step S204), the communication unit 101 connects via the wired network 151 in step S206. It is determined whether or not the first request transmitted from the first main device 131 addressed to the slave device 132 is accepted. When communication unit 101 determines that the first request has been accepted (yes in step S206), relay control unit 103 transmits the first request to slave device 132 in step S205. On the other hand, if the communication unit 101 does not determine acceptance of the first request (no in step S206), the process returns to step S201.

[Other Examples]
The communication control device according to the embodiment described above may make a response corresponding to a request from the communication unit and the wireless communication unit. As a process at this time, when responding to the second main device in [Embodiment 1], the communication control device is linked so as to become a response to the second request composed of a plurality of data addresses to be processed. For example, if there is no response from the slave device to the request sent to the device for a certain period of time, an abnormal timeout response may be issued.

As shown in FIG. 5, the communication control device according to the above-described embodiment includes a CPU (Central Processing Unit) 301, a main storage device 302, an external storage device 303, a network connection device 304, and a wireless connection device. 305 and the like, and each function described above is realized by the operation of the CPU 301 by a program developed in the main storage device 302 . Note that the network connection device 304 connects to the wired network 306 . Also, functions may be distributed among multiple computing devices.

Further, the communication control apparatus in the above-described embodiments can also be configured by a programmable logic device (PLD: Programmable Logic Device) such as FPGA (field-programmable gate array). For example, by providing each of a communication unit, a wireless communication unit, and a relay control unit as circuits in an FPGA logic element, it can be made to function as a communication control device. Each of the communication circuit, the wireless communication circuit, and the relay control circuit connects a predetermined writing device and writes to the FPGA.

As described above, according to the present invention, the first request transmitted from the first main device via the wired network has priority over the second request transmitted from the second main device connected by wireless communication. and send it to the slave device, maintenance and inspection can be performed without greatly affecting control.

It should be noted that the present invention is not limited to the embodiments described above, and many modifications and combinations can be implemented by those skilled in the art within the technical concept of the present invention. It is clear.

DESCRIPTION OF SYMBOLS 100... Communication control apparatus, 101... Communication part, 102... Wireless communication part, 103... Relay control part, 131... First master device, 132... Slave device, 133... Second master device, 151... Wired network.

Claims (2)

a communication unit configured to receive a first request transmitted from a first master device via a wired network to a slave device as a destination;
a wireless communication unit configured to receive a second request transmitted from a second master device connected by wireless communication with the slave device as a destination;
a relay control unit configured to transmit the first request to the slave device with priority over the second request ;
The relay control unit divides the second request for each data address and transmits the second request to the slave device, thereby giving priority to transmission of the first request. a first step of receiving a first request transmitted from a first master device via a wired network to a slave device;
a second step of receiving a second request transmitted from a second master device connected by wireless communication with the slave device as a destination; and a third step of transmitting the first request to the slave device with priority over the second request. with steps and
The third step divides the second request for each data address and transmits the second request to the slave device, thereby giving priority to transmission of the first request.

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