JP6865600B2 - Communication relay device - Google Patents

Description

The present invention relates to a communication relay device that intervenes between two devices that transfer data and relays data transfer from another device.

An HMI (Human Machine Interface) device such as a programmable display is connected to a control device such as a PLC (Programmable Logic Controller) and communicates with the control device for data transfer. For example, Patent Document 1 discloses a programmable display that performs serial communication with a PLC.

Japanese Unexamined Patent Publication No. 2016-126487 (published on July 11, 2016)

In the above system, when you want to acquire data from PLC for the purpose of data collection, data analysis, etc., for example, connect a device such as a data logger to the spare communication port of PLC and acquire the data by the data logger. It is conceivable to do. However, if the PLC does not have a spare communication port, the data cannot be acquired by the data logger.

One aspect of the present invention is to obtain data from a control device that does not have a spare communication port.

In order to solve the above problems, the communication relay device according to one aspect of the present invention performs serial communication between a host device and a control device that reads and writes data in response to a request from the host device. A communication relay device that transmits a request from a data management device that manages data to the control device, and the host through a data transmission path for transmitting data and a first communication path via the data transmission path. A relay processing unit that relays communication between the device and the control device and relays communication between the data management device and the control device through a second communication path via the data transmission line, and the relay processing unit. Is operating, the host device and the control device are connected to the first communication path, while the relay processing unit is not operating, the host device and the control device are connected to each other. It is equipped with a communication path switching unit.

According to the above configuration, in the state where the relay processing unit is operating, the host device and the control device communicate via the first communication path, and the data management device and the control device communicate via the second communication path. To communicate. Therefore, it is possible to communicate between the host device and the data management device while communicating between the host device and the control device. Therefore, even if the control device does not have a spare communication port, it is possible to communicate with the data management device.

Further, when the relay control unit is not operating, communication between the host device and the control device is maintained by connecting the host device and the control device to each other. Therefore, it is possible to avoid the inconvenience that communication between the host device and the control device is not performed when the operation of the relay control unit is not operating.

The communication relay device includes a communication monitoring unit that monitors the presence or absence of communication between the host device and the control device, and when the communication monitoring unit determines that there is no communication, the communication relay device connects to the first communication path. It further includes a switching control unit that controls the communication path switching unit so as to perform an operation of switching between the connection of the host device and the control device and the interconnection of the host device and the control device.

According to the above configuration, the switching operation by the signal path switching unit is performed in a state where communication is not performed between the host device and the control device. As a result, it is possible to prevent data during communication from being lost due to the switching operation.

The communication relay device further includes a priority setting unit that sets a priority for a request from the data management device to the control device and a request from the host device to the control device, and the relay processing unit includes a priority setting unit. , The request from the data management device is transmitted to the control device according to the set priority.

According to the above configuration, the request from the data management device can be efficiently transmitted to the control device by setting the priority according to the amount of communication between the host device and the control device.

The communication relay device further includes a baud rate setting unit that sets the baud rate of communication with the control device to a high-speed baud rate higher than the standard baud rate, and the relay processing unit performs communication with the control device. This is performed at the set high-speed baud rate.

According to the above configuration, communication can be performed at a high speed baud rate between the communication relay device and the control device corresponding to the high speed baud rate. As a result, the communication time between the communication relay device and the control device can be shortened.

In the communication relay device, the relay processing unit individually performs communication processing for the host device and communication processing for the control device.

According to the above configuration, the relay processing unit can send another request to the control device while communicating with the host device. In this way, the communication time can be shortened by performing the two communications at the same time. Therefore, the processing capacity of the communication relay device can be improved.

The communication relay device further includes a request dividing unit that divides the request into a predetermined size when the size of the request from the data management device to the control device exceeds a predetermined value, and the relay processing unit includes a request dividing unit. A divided request from the data management device is transmitted to the control device during a period in which a series of processes of the request from the host device and the response of the control device to the host device in response to the request are not performed. To do.

According to the above configuration, since the individual size of the divided request is reduced, it is possible to suppress waiting for the transmission of the request from the host device to the control device in order to process the request from the data management device. As a result, it is possible to suppress a decrease in communication efficiency between the host device and the control device.

In the communication relay device, the relay processing unit gives priority to a request for writing from the host device to the control device over a request from the data management device to the control device regardless of the priority. , Transmit to the control device.

Writing data from the host device to the control device is often an important request such as an instruction to the control device. Therefore, according to the above configuration, the request for writing from the host device to the control device can be executed with the highest priority.

The communication relay device further includes an error detection unit that detects that an error has occurred in the operation of the relay processing unit, and the communication path switching unit is the host when an error is detected by the error detection unit. The device and the control device are interconnected.

According to the above configuration, when an error occurs in the operation of the relay processing unit, the communication between the host device and the control device is maintained by the interconnection of the host device and the control device. As a result, it is possible to avoid the inconvenience that communication between the host device and the control device becomes impossible due to an error in the operation of the relay processing unit.

According to one aspect of the present invention, there is an effect that data can be easily acquired from a control device that does not have a spare communication port.

It is a block diagram which shows the structure of the control system which concerns on each embodiment of this invention. It is a block diagram which shows the structure of the main part of the communication relay device in the said control system which concerns on Embodiment 1 of this invention. (A) is a diagram showing a state in which the relay control unit of the communication relay device is not operating, and (b) is a diagram showing a state in which the relay control unit of the communication relay device is operating. It is a flowchart which shows the processing procedure at the time of starting the said communication relay device. It is a flowchart which shows the processing procedure by the relay control unit when the communication relay device goes into an offline state. It is a flowchart which shows the processing procedure by the said relay control part when an exception error occurs. (A) is a flowchart showing a processing procedure by the relay control unit during normal operation of the communication relay device, and (b) is a flowchart showing a processing procedure by the relay control unit during abnormal operation of the communication relay device. is there. It is a block diagram which shows the structure of the main part of the communication relay device in the said control system which concerns on Embodiment 2 of this invention. FIG. 5 is a diagram showing a state of communication between a host device and a control device in the control system via the communication relay device shown in FIG. It is a block diagram which shows the structure of the main part of the communication relay device in the said control system which concerns on Embodiment 3 of this invention. It is a figure which shows the concept of communication through a common memory in the communication relay device shown in FIG. (A) is a diagram showing a state of communication between the host device and the control device via the communication relay device shown in FIG. 10, and (b) is a diagram showing the state of communication between the host device and the control device via the communication relay device shown in FIG. And other states of communication between the control devices. It is a figure which shows the other state of the communication between the said host device and the said control device through the communication relay device shown in FIG.

[Embodiment 1]
The first embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 is a block diagram showing a configuration of a control system 100 according to each embodiment including the present embodiment. FIG. 2 is a block diagram showing a configuration of a main part of the communication relay device 20 in the control system 100 according to the first embodiment.

First, the outline of the control system 100 will be described.

As shown in FIG. 1, the control system 100 includes a communication relay device 20, a host device 30, a control device 40, a device 50, a LAN (Local Area Network) 60, and a data management device 70. ..

The communication relay device 20 has a hardware communication path for connecting the host device 30 and the control device 40 by hardware, and a software communication path for connecting the host device 30 and the control device 40 with software. Further, the communication relay device 20 relays the communication between the data management device 70 and the control device 40 in response to a request from the data management device 70 via the software communication path.

The communication relay device 20 and the host device 30 are connected to each other via a serial communication cable so that serial communication can be performed. Similarly, the communication relay device 20 and the control device 40 are connected to each other via a serial communication cable so that serial communication can be performed. The communication relay device 20 includes a serial port COM1 as a communication port for communication with the control device 40. Further, the communication relay device 20 includes a serial port COM2 as a communication port for communication with the host device 30.

The communication relay device 20 and the data management device 70 are connected to each other via a LAN cable, a router, or the like so that communication can be performed via a LAN (Local Area Network) 60.

The control device 40 is a device having a control function, and is composed of, for example, a PLC (Programmable Logic Controller). The control device 40 exchanges data with and from the device 50. As the device 50, input devices such as sensors and switches, and output devices such as actuators, relays, solenoid valves, and indicators are used. Further, the control device 40 may be composed of devices such as a temperature controller and an inverter.

The host device 30 is an HMI device such as a programmable display, and has a display device and a touch panel. The host device 30 transmits data such as a control instruction to the control device 40 by an input operation using the touch panel on the screen displayed on the display device, and receives data such as data related to the device 50 of the control device 40. .. The host device 30 requests the control device 40 to read the data or write the data in order to send and receive such data.

The data management device 70 is a device that performs processing for managing various types of data such as data collection, data analysis, and data writing. The data management device 70 is composed of a personal computer, a dedicated device, and the like.

Next, the hardware configuration of the communication relay device 20 will be described.

As shown in FIG. 1, the communication relay device 20 includes a CPU (Central Processing Unit) 1, a main memory 2, a ROM (Read Only Memory) 3, a first driver / receiver 4, and a second driver / receiver 5. The first UART (Universal Asynchronous Receiver Transmitter) 6, the second UART 7, the first relay 8 (communication path switching unit), the second relay 9 (communication path switching unit), the LAN interface unit 10, and the power supply circuit 11. And a data bus 12 (data transmission line).

The CPU 1 is a processing device that executes a system program for operating the communication relay device 20. Specifically, when executing the system program, the CPU 1 receives data from the main memory 2, the first driver / receiver 4, the second driver / receiver 5, the LAN interface unit 10, and the like, and calculates or calculates the data. After processing, the data is output to the main memory 2, the first driver / receiver 4, the second driver / receiver 5, the LAN interface unit 10, and the like.

Further, the CPU 1 has a built-in watchdog timer 1a. The watchdog timer 1a monitors the operation of the relay control unit 13 by measuring the time interval of the reaction from the relay control unit 13 described later and determining whether or not the measured value exceeds the specified time. The watchdog timer 1a updates the timer when the response from the relay control unit 13 can be acquired within the specified time, and as a timeout error process when the response from the relay control unit 13 cannot be acquired within the specified time. Reset the system. The watchdog timer 1a may be provided outside the CPU 1.

The main memory 2 is a memory constituting the main storage device in the communication relay device 20, and is composed of a DRAM (Dynamic Random Access Memory).

The ROM 3 stores programs (including the above-mentioned system programs) that are indispensable for the operation of the communication relay device 20, such as a BIOS (Basic Input Output System) that is executed when the communication relay device 20 is started up or reset.

The first driver / receiver 4 is a receiving circuit that receives received data RxD from the host device 30, and is a transmitting circuit that transmits transmission data TxD to the host device 30.

The second driver / receiver 5 is a receiving circuit that receives received data RxD from the control device 40, and is a transmitting circuit that transmits transmission data TxD to the control device 40.

The first driver / receiver 4 and the second driver / receiver 5 correspond to general serial communication standards (RS-232C, RS-422, RS-485, etc.).

The first UART 6 is a circuit that converts a pacing-synchronized serial signal output from the first driver / receiver 4 into a parallel signal and outputs the serial signal to the data bus 12. Further, the first UART 6 is a circuit that converts a parallel signal input from the data bus 12 to the first driver / receiver 4 into a serial signal of the pace synchronization method. Further, the first UART 6 has a built-in buffer for transmission and a buffer for reception.

The second UART 7 is a circuit that converts a pacing-synchronized serial signal output from the second driver / receiver 5 into a parallel signal and outputs the serial signal to the data bus 12. Further, the second UART 7 is a circuit that converts a parallel signal input from the data bus 12 to the second driver / receiver 5 into a serial signal of the pace synchronization method. Further, the second UART 7 has a built-in buffer for transmission and a buffer for reception.

The first relay 8 is interposed between the serial port COM2 and the first driver / receiver 4. The first relay 8 connects the host device 30 and the control device 40 to each other and transmits communication data from the control device 40 to the host device 30 between the host device 30 and the first driver / receiver 4. It is a circuit that switches between the communication path and the communication path of. Therefore, the first relay 8 has an output terminal 8a, a first input contact 8b, and a second input contact 8c. The output terminal 8a is connected to the serial port COM2. The first input contact 8b is connected to the output terminal of the first driver / receiver 4. The second input contact 8c is connected to a communication path between the serial port COM1 and the input terminal of the second driver / receiver 5 to which communication data from the control device 40 is transmitted.

The second relay 9 is interposed between the serial port COM1 and the second driver / receiver 5. The second relay 9 connects the host device 30 and the control device 40 to each other and transmits communication data from the host device 30 to the control device 40, and between the control device 40 and the second driver / receiver 5. It is a circuit that switches between the communication path and the communication path of. Therefore, the second relay 9 has an output terminal 9a, a first input contact 9b, and a second input contact 9c. The output terminal 9a is connected to the serial port COM1. The first input contact 9b is connected to the output terminal of the second driver / receiver 5. The second input contact 9c is connected to a communication path between the serial port COM2 and the input terminal of the first driver / receiver 4 to which communication data from the host device 30 is transmitted.

Switching between the first relay 8 and the second relay 9 is controlled by the CPU 1 (switching control unit 18 described later).

In this embodiment, the first relay 8 is used to switch the connection between the first driver / receiver 4 to the host device 30 and the control device 40, and the second driver / receiver 5 to the control device 40 and the host device 30 are connected to each other. The second relay 9 is used for switching the connection. For such connection switching, not only the first relay 8 and the second relay 9 but also an electronically controlled semiconductor switch or the like capable of switching control by the switching control unit 18 can be used.

In the following description, the state in which the first relay 8 connects the output terminal 8a and the second input contact 8c and the state in which the second relay 9 connects the output terminal 9a and the second input contact 9c are referred to as a bypass connection state. Refer to. Further, a state in which the first relay 8 connects the output terminal 8a and the first input contact 8b and a state in which the second relay 9 connects the output terminal 9a and the first input contact 9b are referred to as a relay connection state.

The LAN interface unit 10 is an interface for connecting an external device such as the data management device 70 to the communication relay device 20 so as to enable LAN communication. The LAN interface unit 10 is connected to the LAN 60.

The power supply circuit 11 is a circuit that supplies electric power to each part (main memory 2, ROM3, first driver / receiver 4, second driver / receiver 5, first UART6, second UART7, LAN interface part 10, etc.) of the communication relay device 20. Is. The power supply circuit 11 is turned on when the communication relay device 20 is started, and the power supply circuit 11 is turned off when the communication relay device 20 is stopped.

Subsequently, the system configuration of the communication relay device 20 will be described with reference to FIG. In FIG. 2, for convenience, the first driver / receiver 4, the second driver / receiver 5, the first UART6, and the second UART7 are omitted.

As shown in FIG. 2, the communication relay device 20 includes a relay control unit 13 in order to realize the communication relay function. The relay control unit 13 is a part having a communication relay function realized by executing the communication relay program by the CPU 1. The communication relay function includes a function of switching between the hardware communication path and the software communication path described above, and a function of relaying communication between the data management device 70 and the control device 40 via the software communication path.

The relay control unit 13 relays the start / stop control unit 14, the reception data monitoring unit 15 (communication monitoring unit), the offline setting unit 16, the error processing unit 17 (error detection unit), the switching control unit 18, and the relay. It has a processing unit 19.

The start / stop control unit 14 initializes each unit (for example, initialization of the communication driver) from the time when the power supply circuit 11 is turned on until the relay control unit 13 becomes operable. Further, the start / stop control unit 14 performs termination processing of each unit from when the power supply circuit 11 is turned off until the relay control unit 13 stops operating. Further, the start / stop control unit 14 gives a pre-start notification to the switching control unit 18, which will be described later, during the period before the start from when the power supply circuit 11 is turned on until the relay control unit 13 becomes operable. Further, the start / stop control unit 14 gives an operable notification to the switching control unit 18, which will be described later, that the relay control unit 13 has become operable after the power supply circuit 11 is turned on. Further, the start / stop control unit 14 gives an operation stop notification to the switching control unit 18 that the relay control unit 13 stops the operation when the power supply circuit 11 is turned off.

The reception data monitoring unit 15 monitors the presence / absence of communication between the host device 30 and the control device 40 by monitoring the received data RxD received from the host device 30 and the control device 40. Specifically, the reception data monitoring unit 15 monitors the state of the packets included in the reception data RxD, and when the interval between the transmitted packets is equal to or greater than a predetermined interval, the switchable notification is switched and controlled. Give to part 18. The above-mentioned predetermined interval is the shortest time during which it can be determined that packet communication is not being performed.

The offline setting unit 16 is provided to make various settings (offline setting) during a period (offline period) in which the relay processing unit 19 described later does not perform relay processing. Examples of the settings performed by the offline setting unit 16 include communication settings such as baud rate and IP address settings. The setting for the offline setting unit 16 is performed from a setting device 80 (personal computer or the like) (not shown) connected to the LAN 60, but a communication relay device including a display unit for displaying the setting screen and an input unit for inputting the setting. It may be done by 20. Further, the offline setting unit 16 notifies the switching control unit 18 that the offline setting is started and the offline setting is finished.

When the error processing unit 17 detects that an exception error has occurred at the time of starting or operating the relay control unit 13, the error processing unit 17 notifies the switching control unit 18 of the occurrence of the exception error. Further, when the error processing unit 17 detects the time-out of the watchdog timer 1a, the error processing unit 17 notifies the switching control unit 18 of the occurrence of a time-out error.

The switching control unit 18 controls to switch the connection state of the first relay 8 and the second relay 9 between the bypass connection state and the relay connection state. Specifically, the switching control unit 18 outputs a switching control signal for controlling switching between the first relay 8 and the second relay 9 to the first relay 8 and the second relay 9 as follows.

When the switching control unit 18 receives the pre-start notification and the operation stop notification from the start / stop control unit 14, the switching control unit 18 connects the output terminal 8a of the first relay 8 and the second input contact 8c, and the second relay 9 Outputs a switching control signal that connects the output terminal 9a of the above and the second input contact 9c. Further, when the switching control unit 18 receives the operation enablement notification from the start / stop control unit 14, the switching control unit 18 connects the output terminal 8a of the first relay 8 and the first input contact 8b, and outputs the second relay 9. A switching control signal for connecting the terminal 9a and the first input contact 9b is output.

When the switching control unit 18 receives the switchable notification from the received data monitoring unit 15, the switching control unit 18 switches the current connection state of the first relay 8 and the second relay 9 between the bypass connection state and the relay connection state. Outputs a switching control signal to.

The switching control unit 18 switches from the relay connection state to the bypass connection state when the switching control unit 18 further receives the switchable notification from the reception data monitoring unit 15 in the state of receiving the notification from the offline setting unit 16 to start the offline setting. Output the control signal. Further, when the switching control unit 18 receives a notification from the offline setting unit 16 to end the offline setting and further receives a switchable notification from the received data monitoring unit 15, the switching control unit 18 changes from the bypass connection state to the relay connection state. Outputs a switching control signal for switching.

When the switching control unit 18 receives a notification of the occurrence of an exception error or a notification of the occurrence of a watchdog timeout error from the error processing unit 17, it outputs a switching control signal for switching from the relay connection state to the bypass connection state.

The relay processing unit 19 transmits the received data RxD from the host device 30 input from the serial port COM2 via the data bus 12 during the period when the first relay 8 and the second relay 9 are switched to the relay connection state. Output to the first input contact 9b of the second relay 9. Further, the relay processing unit 19 transfers the received data RxD from the control device 40 input from the serial port COM1 to the data bus 12 during the period when the first relay 8 and the second relay 9 are switched to the relay connection state. The data is output to the first input contact 8b of the first relay 8 via the above.

Further, the relay processing unit 19 has a priority changing unit 191 (priority setting unit). The priority change unit 191 changes the priority for a request for reading or writing data from the data management device 70. There are three priority levels: low level, medium level, and high level.

The low level (default) is a level that gives the highest priority to the main communication between the host device 30 and the control device 40. At a low level, interrupt communication for an interrupt request from the data management device 70 is not performed except in a situation where the request command from the host device 30 is not transmitted.

The medium level is a level at which main communication (twice) between the host device 30 and the control device 40 and interrupt communication for an interrupt request are alternately performed. At the medium level, specifically, one interrupt communication is performed for two transmissions of the request command from the host device 30.

The high level is a level that gives priority to interrupt communication to the extent that it does not interfere with the main communication (to the extent that a timeout does not occur).

The number of interrupt communications for one main communication at the medium level and the high level can be set as appropriate. In addition, the priority level can be changed by the user.

The process of communication relay by the communication relay device 20 configured as described above will be described. FIG. 3A is a diagram showing a state in which the relay control unit 13 is not operating, and FIG. 3B is a diagram showing a state in which the relay control unit 13 is operating. FIG. 4 is a flowchart showing a processing procedure at the time of starting the communication relay device 20. FIG. 5 is a flowchart showing a processing procedure by the relay control unit 13 when the communication relay device 20 goes into the offline state. FIG. 6 is a flowchart showing a processing procedure by the relay control unit 13 when an exception error occurs. FIG. 7A is a flowchart showing a processing procedure by the relay control unit 13 during normal operation of the communication relay device 20. FIG. 7B is a flowchart showing a processing procedure by the relay control unit 13 at the time of abnormal operation of the communication relay device 20.

First, a communication relay process at the time of starting the relay control unit 13 will be described.

When the power of the communication relay device 20 is turned off, the first relay 8 and the second relay 9 are in the bypass connection state. Therefore, as shown in FIG. 3A, the host device 30 and the control device 40 do not go through the relay control unit 13, but the bypass communication path 25 by the first relay 8 and the second relay 9 (the hardware described above). Communication is in a state of being connected to each other via a communication path). In this state, as shown in FIG. 2, in the first relay 8, the output terminal 8a is connected to the second input contact 8c, and in the second relay 9, the output terminal 9a is connected to the second input contact 9c. ..

Specifically, data is transmitted and received as follows. As shown in FIG. 1, the data transmitted from the host device 30 is output from the serial port COM1 as transmission data TxD via the second input contact 9c and the output terminal 9a of the second relay 9 through the serial port COM2. Received by the control device 40. Further, the data transmitted from the control device 40 is output from the serial port COM2 as transmission data TxD via the second input contact 8c and the output terminal 8a of the first relay 8 through the serial port COM1 and received by the host device 30. Will be done.

As shown in FIG. 4, when the power of the communication relay device 20 is turned on and power is supplied from the power supply circuit 11 to each part of the communication relay device 20, the start / stop control unit 14 processes at the time of startup. Is started (step S1).

The start / stop control unit 14 initializes a communication driver that controls communication via the first driver / receiver 4 and the second driver / receiver 5 as a process at the time of startup (step S2). The start / stop control unit 14 determines whether or not the predetermined initialization process has been completed (step S3), and if not (NO), continues the initialization process. When the predetermined initialization process by the start / stop control unit 14 is completed (YES in step S3), the reception data monitoring unit 15 monitors the reception data RxD from the host device 30 and the control device 40 (step S4).

The reception data monitoring unit 15 determines whether or not the packet transmission between the host device 30 and the control device 40 is completed as a result of monitoring the received data RxD (step S5). When the reception data monitoring unit 15 determines that the packet transmission is not completed (NO in step S5), it subsequently determines whether or not the packet transmission is completed. Further, when the reception data monitoring unit 15 determines that the packet transmission is completed (YES in step S5), the reception data monitoring unit 15 determines whether or not there is any data from the host device 30 or the control device 40 (step S6). When the reception data monitoring unit 15 determines in step S6 that there is some data (YES), the reception data monitoring unit 15 performs the process of step S5.

When the reception data monitoring unit 15 determines in step S6 that there is no data (NO), it determines whether or not 10 ms has elapsed after confirming that there is no data (step S7). If it is determined in step S7 that 10 ms has not elapsed since the reception data monitoring unit 15 confirmed that there is no data (NO), the received data monitoring unit 15 performs the process of step S5.

When it is determined (YES) that 10 ms has elapsed since the received data monitoring unit 15 confirmed that there is no data in step S7, the first relay 8 and the second relay 9 are switched and controlled by the switching control unit 18. The relay connection state is switched by the signal (step S8). In this state, the bypass connection is broken.

The interval between packets exchanged between the host device 30 and the control device 40 is 10 ms. Therefore, the received data monitoring unit 15 can determine that there is no packet communication when the period during which the packet cannot be confirmed exceeds 10 ms. The packet interval is not limited to 10 ms and can be set arbitrarily.

In this state, the relay processing unit 19 performs a process of relaying each communication between the host device 30 and the control device 40 and between the data management device 70 and the control device 40 (step S9). The relay processing unit 19 determines whether or not a data transmission request (interrupt request) from the data management device 70 has been received (step S10). If the relay processing unit 19 determines in step S10 that the data transmission request has not been received (NO), the relay processing unit 19 continues the processing of step S9. Further, when the relay processing unit 19 determines that the data transmission request has been received in step S10 (YES), the relay processing unit 19 generates a packet based on the data transmission request and sends the packet to the serial port COM1 (step S11).

The relay processing unit 19 transmits the packet to the control device 40 according to the priority as described above. Depending on the usage status of the control system 100, the host device 30 may be used as a monitor with almost no operation. In such a situation, real-time performance is not required so much for the main communication between the host device 30 and the control device 40. In such a case, the priority changing unit 191 can change the priority of the interrupt communication to a high level according to the instruction of the user, and the interrupt communication can be performed frequently. In addition, it may be desirable to refrain from interrupt communication in a specific time zone. In such a case, the priority changing unit 191 changes the priority of the interrupt communication to a low level according to the instruction of the user. As a result, the communication relay device 20 can reduce the frequency of interrupt communication and give priority to main communication.

In this way, the priority changing unit 191 sets the priority so that the priority can be changed according to the circumstances of the control system 100. However, it is desirable that the writing of data from the host device 30 to the control device 40 has the highest priority. Therefore, when the read request from the data management device 70 and the write command from the host device 30 conflict with each other, the write command has priority. For example, in the production line, when the product type of the manufactured product is changed, the recipe data may be simultaneously transmitted from the host device 30 to the control device 40 during a lunch break or the like. In such a case, even if the interrupt priority is set, the write process from the host device 30 is prioritized.

When the control device 40 receives the packet transmitted from the communication relay device 20, the control device 40 reads and transmits the data in response to the data transmission request from the data management device 70.

When the relay processing unit 19 receives the data from the control device 40, it converts the packet into response data and returns it to the data management device 70 via the LAN interface unit 10 (step S12).

As described above, in the state where the relay processing unit 19 is operating, as shown in FIG. 3B, the host device 30 and the control device 40 relay including the first relay 8 and the second relay 9. Communication is performed through the first relay communication path 26 (the software communication path described above, the first communication path) formed by the processing unit 19 via the data bus 12. Further, the data management device 70 and the control device 40 communicate with each other through the second relay communication path 27 (second communication path) formed by the relay processing unit 19 via the data bus 12. Therefore, while communicating between the host device 30 and the control device 40, it is possible to communicate between the host device 30 and the data management device 70 in the meantime. Therefore, even if the control device 40 does not have a spare communication port, it is possible to communicate with the data management device 70.

Further, the bypass connection state is secured before the relay control unit 13 is activated, and when the relay control unit 13 is activated, the bypass connection state is switched to the relay connection state. As a result, as shown in FIG. 3A, communication between the host device 30 and the control device 40 is performed via the first relay 8 and the second relay 9 even if the operation of the relay control unit 13 is stopped. It is maintained via the bypass communication path 25. Therefore, there is no inconvenience that communication between the host device 30 and the control device 40 is not performed when the operation of the relay control unit 13 is stopped.

Further, when the bypass connection state is switched to the relay connection state, the switching operation of the first relay 8 and the second relay 9 is performed in a state where communication is not performed between the host device 30 and the control device 40. Even when the relay connection state is switched to the bypass connection state, the switching operation of the first relay 8 and the second relay 9 is performed in a state where communication is not performed between the host device 30 and the control device 40. As a result, it is possible to prevent data during communication from being lost due to the switching operation of the first relay 8 and the second relay 9.

When the power is cut off, the power supply of the communication relay device 20 is forcibly turned off, so that the switching control unit 18 cannot control the switching of the first relay 8 and the second relay 9. For such inconvenience, the contact type between the output terminal 8a and the second input contact 8c in the first relay 8 and between the output terminal 9a and the second input contact 9c in the second relay 9 is changed to b. Set as a contact (normally closed). As a result, when the switching control signal from the switching control unit 18 becomes no signal (low level) at the time of power interruption, the first relay 8 and the second relay 9 are forcibly switched to the bypass connection state. Alternatively, the communication relay device 20 may separately include a circuit for forcibly switching the first relay 8 and the second relay 9 to the bypass connection state when the power supply circuit 11 is turned off. As a result, even if the switching control unit 18 does not function at the time of power failure, the first relay 8 and the second relay 9 are switched to the bypass connection state by the above circuit.

Further, as a semiconductor switch that can be switched to the bypass connection state at the time of power failure and replaces the first relay 8, a normally-off type first transistor is arranged between the output terminal 8a and the first input contact 8b, and the output terminal. A switch in which a normalion type second transistor is arranged between the 8a and the second input contact 8c can be considered. Similarly, as a semiconductor switch that replaces the second relay 9, a normally-off type first transistor is arranged between the output terminal 9a and the first input contact 9b, and between the output terminal 9a and the second input contact 9c. A switch in which a normalion type second transistor is arranged is conceivable. In such a switch, when the gate voltage is not applied, the first transistor is turned off while the second transistor is turned on, and when the gate voltage is applied, the first transistor is turned on while the second transistor is turned off. .. As a result, when the power supply circuit 11 of the communication relay device 20 is turned off at the time of power failure, the gate voltage is not applied to the switch, so that the first transistor is turned off, while the second transistor is turned on, so that the bypass connection state is set. can get.

Subsequently, the processing of communication relay at the time of offline setting by the offline setting unit 16 will be described.

First, when the offline setting unit 16 receives an instruction for offline setting from the setting device 80 connected to the LAN 60, the relay processing unit 19 shifts to the offline state. When the offline state is entered, the relay processing unit 19 completes the transmission / reception processing between the host device 30 and the control device 40 (step S21). When the transmission / reception process is completed, the reception data monitoring unit 15 determines whether or not there is any data from the host device 30 or the control device 40 (step S22). When the reception data monitoring unit 15 determines in step S22 that there is some data (YES), the process returns to step S21.

When the reception data monitoring unit 15 determines in step S22 that there is no data (NO), it determines whether or not 10 ms has elapsed after confirming that there is no data (step S23). When the reception data monitoring unit 15 determines in step S23 that 10 ms has not elapsed since confirming that there is no data (NO), the process returns to step S21.

When it is determined (YES) that 10 ms has elapsed since the received data monitoring unit 15 confirmed that there is no data in step S23, the first relay 8 and the second relay 9 are switched and controlled by the switching control unit 18. It switches to the bypass connection state by the signal (step S24).

When the state shifts to the bypass connection state, the offline setting unit 16 executes the offline setting process in response to the operation from the setting device 80 (step S25).

The offline setting unit 16 has a function like a Web server, and provides a screen for offline setting to the setting device 80 in HTML (Hyper Text Markup Language) format or the like. The screen is provided with items for setting communication settings such as baud rate and setting an IP address for LAN60. As a result, the setting device 80 can be set by the Web browser when the communication relay device 20 is accessed via the LAN 60.

When the offline setting unit 16 finishes the offline setting (step S26), the received data monitoring unit 15 monitors the received data RxD from the host device 30 and the control device 40 (step S27).

After that, the received data monitoring unit 15 performs the same processing as in steps S5 to S7 described above (steps S28 to S30). Further, the first relay 8 and the second relay 9 perform the same processing as in step S8 described above after step S30 (step S31). As a result, the relay processing unit 19 shifts to the online state (step S32). In this state, the relay processing unit 19 performs a process of relaying each communication between the host device 30 and the control device 40 and between the data management device 70 and the control device 40 (step S33).
In this way, when the offline setting is performed, the relay connection state can be switched to the bypass connection state. As a result, even if the relay operation by the relay processing unit 19 is stopped, the communication between the host device 30 and the control device 40 is maintained by the bypass connection state via the first relay 8 and the second relay 9. Further, when shifting from the online state to the offline state, and when shifting from the offline state to the online state, the first relay 8 and the second relay 9 are in a state where communication is not performed between the host device 30 and the control device 40. Switching operation is performed. As a result, it is possible to prevent data during communication from being lost due to the switching operation of the first relay 8 and the second relay 9.

Subsequently, the processing of communication relay when an exception error occurs and a watchdog timeout error occurs will be described.

When an exception error occurs, as shown in FIG. 6, first, the relay processing unit 19 communicates between the host device 30 and the control device 40 and between the data management device 70 and the control device 40, respectively. The relay process is performed (step S41). When the error processing unit 17 detects that an exception error has occurred, it notifies the switching control unit 18 that interrupt processing due to the exception error is required (step S42). The first relay 8 and the second relay 9 are switched to the bypass connection state by the switching control signal from the switching control unit 18 (step S43). When the bypass connection state is switched, the relay processing by the relay processing unit 19 ends (step S44).

When the relay control unit 13 is operating normally, as shown in FIG. 7A, the relay processing unit 19 is between the host device 30 and the control device 40, and between the data management device 70 and the control device 40. A process of relaying each communication is performed between the two (step S51). Since the watchdog timer 1a monitors the entire operation of the system of the communication relay device 20, that is, the relay control unit 13, communication between the data management device 70 and the host device 30 and the control device 40 by the relay control unit 13 is normal. If so, the timer is updated (step S52).

The relay processing unit 19 determines whether or not a data transmission request from the data management device 70 has been received (step S53). When the relay processing unit 19 determines that the data transmission request has been received in step S53 (YES), the relay processing unit 19 acquires the data requested from the control device 40 by performing the processes of steps S11 and S12 described above, and the data management device 70. The process of transmitting to is performed (step S54).

Next, the watchdog timer 1a updates the timer when communication is normal (step S55), as in step S52. If the relay processing unit 19 determines in step S53 that the data transmission request has not been received (NO), the watchdog timer 1a processes step S55. After that, the process returns to step S51.

When an abnormality occurs in the operation of the relay control unit 13, the communication path is switched as shown in FIG. 7B. First, the relay processing unit 19 performs a process of relaying each communication between the host device 30 and the control device 40 and between the data management device 70 and the control device 40 (step S61).

The watchdog timer 1a monitors the operation of the relay control unit 13, and times out because the response from the relay control unit 13 could not be acquired within the specified time from the previous timer update. When the error processing unit 17 detects the timeout of the watchdog timer 1a, it notifies the switching control unit 18 that interrupt processing due to the timeout error is required (step S62).

The first relay 8 and the second relay 9 are switched to the bypass connection state by the switching control signal from the switching control unit 18 (step S63). When the bypass connection state is switched, the relay processing by the relay processing unit 19 ends (step S64).

In this way, when an exception error and a watchdog timeout error occur in the relay control unit 13, the connection state between the host device 30 and the control device 40 is switched to the bypass connection state. This avoids the inconvenience that communication between the host device 30 and the control device becomes impossible when some problem occurs in the relay control unit 13 and the operation of the relay processing unit 19 falls into an abnormal state. Can be done.

When a watchdog timeout error occurs, the first relay 8 and the second relay 9 may be switched to the bypass connection state by direct control from the error processing unit 17.

If there is no function to switch to the bypass connection state as described above, and if an abnormality occurs in the relay control unit 13 while the power of the communication relay device 20 is on, the relay connection state by the relay processing unit 19 cannot be maintained. , It interferes with communication.

[Embodiment 2]
The second embodiment of the present invention will be described below with reference to FIGS. 1, 8 and 9. In the present embodiment, the same reference numerals will be added to the components having the same functions as the components in the first embodiment, and the description thereof will be omitted.

FIG. 8 is a block diagram showing a configuration of a main part of the communication relay device 21 in the control system 100 according to the second embodiment. FIG. 9 is a diagram showing a state of communication between the host device 30 and the control device 40 in the control system 100 via the communication relay device 21. In FIG. 9, the vertical axis represents time.

As shown in FIG. 1, the control system 100 includes a communication relay device 21, a host device 30, a control device 40, a device 50, a LAN 60, and a data management device 70.

As shown in FIG. 8, the communication relay device 21 includes a relay control unit 13A in order to realize the communication relay function. The relay control unit 13A is a part having the above-mentioned communication relay function, which is realized by executing the communication relay program by the CPU 1.

Like the relay control unit 13 in the communication relay device 20 of the first embodiment, the relay control unit 13A switches between the start / stop control unit 14, the reception data monitoring unit 15, the offline setting unit 16, and the error processing unit 17. It has a control unit 18. Further, the relay control unit 13A has a relay processing unit 19A. The relay processing unit 19A has a priority changing unit 191 like the relay processing unit 19 of the relay control unit 13, but also has a baud rate changing unit 192 (baud rate setting unit).

The baud rate changing unit 192 changes the baud rate of communication with the control device 40 between a standard baud rate (standard baud rate) and a high-speed baud rate faster than the standard baud rate.

Some PLCs constituting the control device 40 can be changed to a high-speed baud rate by a command. Therefore, the baud rate changing unit 192 sends the above command to the PLC in order to increase the communication speed with such a PLC, and changes the baud rate from the standard baud rate to the high speed baud rate.

As a result, as shown in FIG. 9, the communication relay device 21 communicates with the host device 30 at the standard baud rate in relaying the communication between the host device 30 whose baud rate cannot be changed and the control device 40 whose baud rate has been changed to the high speed baud rate. , Communicate with the control device 40 at a high speed baud rate. Therefore, the total communication time can be shortened.

For example, in the communication relay device 20 of the first embodiment, it is assumed that communication with the host device 30 takes 10 ms and communication with the control device 40 takes 10 ms. On the other hand, when the baud rate of the control device 40 can be increased five times, the communication relay device 21 communicates with the control device 40 in 2 ms, so that the total communication time is 8 ms as compared with the communication relay device 20. Can be shortened. As a result, the processing capacity of the communication relay device 21 can be improved. Further, by using this shortened time for communication of the data management device 70, for example, the interrupt communication by the data management device 70 is processed without delaying the communication between the host device 30 and the control device 40. be able to.

[Embodiment 3]
The third embodiment of the present invention will be described below with reference to FIGS. 1, 10 to 13. In the present embodiment, the same reference numerals will be added to the components having the same functions as the components in the first embodiment, and the description thereof will be omitted.

FIG. 10 is a block diagram showing a configuration of a main part of the communication relay device 22 in the control system 100 according to the third embodiment. FIG. 11 is a diagram showing the concept of communication via the first common memory 28 and the second common memory 29 in the communication relay device 22. FIG. 12A is a diagram showing a state of communication between the host device 30 and the control device 40 via the communication relay device 22. FIG. 12B is a diagram showing another state of communication between the host device 30 and the control device 40 via the communication relay device 22. FIG. 13 is a diagram showing still another state of communication between the host device 30 and the control device 40 via the communication relay device 22.

As shown in FIG. 1, the control system 100 includes a communication relay device 22, a host device 30, a control device 40, a device 50, a LAN 60, and a data management device 70. However, in addition to the first driver / receiver 4 and the second driver / receiver 5 shown in FIG. 1, the communication relay device 22 includes the first common memory 28 and the second common memory 29 shown in FIG. I have.

The first common memory 28 is a memory commonly used for communication between the host device 30 and the control device 40. The first common memory 28 has a reception memory 28a for transmitting the reception data RxD and a transmission memory 28b for transmitting the transmission data TxD.

The second common memory 29 is a memory commonly used for communication between the control device 40 and the LAN 60. The second common memory 29 has a reception memory 29a for transmitting the reception data RxD and a transmission memory 29b for transmitting the transmission data TxD.

As shown in FIG. 10, the communication relay device 22 includes a relay control unit 13B in order to realize the communication relay function. The relay control unit 13B is a part having the above-mentioned communication relay function, which is realized by executing the communication relay program by the CPU 1.

Like the relay control unit 13 in the communication relay device 20 of the first embodiment, the relay control unit 13B switches between the start / stop control unit 14, the reception data monitoring unit 15, the offline setting unit 16, and the error processing unit 17. It has a control unit 18. Further, the relay control unit 13B has a relay processing unit 19B. The relay processing unit 19B has a priority changing unit 191 like the relay processing unit 19 of the relay control unit 13, but further has a relay adjusting unit 193 (request dividing unit).

Further, as shown in FIG. 11, the relay processing unit 19 processes the communication of the serial port COM1 with the control device 40 by the COM1 thread on the serial port COM1 side. Further, the relay processing unit 19 processes the communication of the serial port COM2 with the host device 30 by the COM2 thread on the serial port COM2 side. Further, the relay processing unit 19 processes the communication with the data management device 70 for the LAN 60 by the LAN thread.

The relay adjustment unit 193 divides the interrupt request when the size of the interrupt request from the data management device 70 exceeds a predetermined value. The size for dividing the interrupt request is set in advance, but it may be set by the user. The relay processing unit 19 issues a divided data transmission request between the communication relay device 22 and the control device 40 during a period in which the request of the host device 30 and the response of the control device 40 to the request are not made. It is transmitted to the control device 40. However, the above request and response are performed as a series of processes.

In the control system 100 configured as described above, as shown in FIG. 11, the request from the host device 30 is received via the serial port COM2, then processed by the COM2 thread and processed via the reception memory 28a. It is sent to the COM1 thread. The request is processed by the COM1 thread and then transmitted to the control device 40 via the serial port COM1.

On the other hand, the response from the control device 40 is received via the serial port COM1, processed by the COM1 thread, and sent to the COM2 thread via the transmission memory 28b. The response is processed by the COM2 thread and then transmitted to the host device 30 via the serial port COM2.

Further, the request from the data management device 70 is received via the LAN 60, then processed by the LAN thread and sent to the COM1 thread via the reception memory 29a. The request is processed by the COM1 thread and then transmitted to the control device 40 via the serial port COM1.

On the other hand, the response from the control device 40 is received via the serial port COM1, processed by the COM1 thread, and sent to the LAN thread via the transmission memory 29b. The response is processed by the LAN thread and then transmitted to the data management device 70 via the LAN 60.

In this way, the relay processing unit 19 individually multitasks the communication processing on the control device 40 side and the communication processing on the host device 30 side in the COM1 thread and the COM2 thread, respectively. Further, when an interrupt request is generated from the data management device 70, the relay processing unit 19 uses the COM1 thread and the LAN thread as the COM1 thread and the LAN thread, respectively, for communication processing and the data management device on the control device 40 side, as shown by the broken line in FIG. Communication processing on the 70 side is performed individually by multitasking. Moreover, the COM1 thread processes the request of the host device 30 and the request of the interrupt from the data management device 70, but does not process the other request while processing one request (exclusive processing).

As a result, the communication relay device 22 can transmit another request to the control device 40 while communicating with the host device 30. When this process is executed serially, one communication is performed and then the other communication is performed, so that the other communication is awaited. On the other hand, the communication time can be shortened by performing the two communications at the same time. Therefore, the processing capacity of the communication relay device 22 can be improved by separating the processing between the host device 30 side and the control device 40 side.

Further, normal communication between the host device 30 and the control device 40 via the communication relay device 22 is performed as shown in FIG. 12 (a). The communication relay device 22 (relay processing unit 19B) transfers the request from the host device 30 to the control device 40, and transfers the response from the control device 40 to the request to the host device 30. As a result, the communication time T1 is settled within the timeout time, so that no timeout occurs.

Further, in the control system 100, the communication when the data transmission request is transmitted from the data management device 70 during the communication between the host device 30 and the control device 40 via the communication relay device 22 is shown in FIG. 12 (b). ) Is performed. The communication relay device 22 (relay processing unit 19B) sends an interrupt request EQU (indicated by a thick alternate long and short dash line) from the data management device 70 when communication is being performed between the host device 30 and the control device 40. receive. Then, the communication relay device 22 receives data from the data management device 70 as shown by a thin alternate long and short dash line during the period when the control device 40 does not respond to the request of the host device 30 with the control device 40. Performs interrupt communication according to the transmission request. Then, the communication relay device 22 returns the interrupt response RES (indicated by a thick alternate long and short dash line) to the data management device 70.

If the next request is transmitted from the host device 30 while the interrupt communication is being performed, the request of the host device 30 from the communication relay device 22 to the control device 40 depends on the timing at which the request is issued. Transfer may be waited until the end of interrupt communication. Even in such a case, if the communication time T2 is within the timeout time, no timeout occurs.

However, if the size of the interrupt request EQU is too large and the interrupt communication takes a long time, the waiting time waited for the request of the host device 30 to be transferred from the communication relay device 22 to the control device 40 becomes long. As a result, when the communication time T2 exceeds the timeout time, a timeout occurs.

Therefore, when the size of the interrupt request EQU exceeds a predetermined value, the relay adjustment unit 193 divides the interrupt request EQU into a predetermined division size. As a result, the individual sizes of the divided interrupt request EQUs are reduced, so that even if interrupt communication is performed as shown by a thin alternate long and short dash line in FIG. 13, the above-mentioned standby time can be suppressed or eliminated. be able to. As a result, the communication time T3 is settled within the timeout time, so that no timeout occurs.

Further, when the communication between the host device 30 and the control device 40 is not frequently performed, even if a large size data is requested to be read / written, the influence on the communication between the host device 30 and the control device 40 is not affected. small. Therefore, in such a case, the request is transmitted to the control device 40 as it is without being divided. As a result, the time required for interrupt communication can be shortened. Therefore, the processing efficiency of the data management device 70 can be improved.

[Example of realization by software]
The control blocks (particularly the relay control unit 13) of the communication relay devices 20 to 21 are realized by software using the CPU 1 as described above.

The object of the present invention is achieved by the CPU 1 reading the communication relay program from the ROM 3 and executing the communication relay devices 20 to 21. As the recording medium, in addition to the ROM 3, a “non-temporary tangible medium” such as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, the communication relay program may be supplied to the computer via an arbitrary transmission medium (communication network, broadcast wave, etc.) capable of transmitting the communication relay program. It should be noted that one aspect of the present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the above program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention.

8 1st relay (communication path switching unit)
9 Second relay (communication path switching unit)
12 Data bus (data transmission line)
15 Received data monitoring unit (communication monitoring unit)
16 Offline setting unit 17 Error processing unit (Error detection unit)
18 Switching control unit 19, 19A, 19B Relay processing unit 20-21 Communication relay device 25 Bypass communication path 26 1st relay communication path (1st communication path)
27 Second relay communication path (second communication path)
30 Host equipment 40 Control equipment 70 Data management equipment 191 Priority change unit (Priority setting unit)
192 Baud rate change section (Baud rate setting section)
193 Relay adjustment section (request division section)

Claims (6)

Communication between the host device and the control device that reads and writes data in response to the request from the host device, and also transmits the request from the data management device that manages the data to the control device. It ’s a relay device,
A data transmission line that transmits data and
The communication between the host device and the control device is relayed through the first communication path via the data transmission path, and the data management device and the control device are connected through the second communication path via the data transmission path. And the relay processing unit that relays the communication of
When the relay processing unit is operating, the host device and the control device are connected to the first communication path, while when the relay processing unit is not operating, the host device and the control device are connected. Communication path switching unit that connects to each other ,
A first transmission / reception circuit that transmits / receives data to / from the host device,
A second transmission / reception circuit for transmitting / receiving data to / from the control device is provided.
The communication path switching unit includes a first relay provided between the host device and the first transmission / reception circuit, and a second relay provided between the control device and the second transmission / reception circuit.
The first relay is connected to an output terminal connected to the host device, a first input contact connected to the first transmission / reception circuit, and a second transmission / reception circuit to input data from the control device. Has a second input contact
The second relay is connected to the output terminal connected to the control device, the first input contact connected to the second transmission / reception circuit, and the first transmission / reception circuit to input data from the host device. Has a second input contact
When the relay processing unit is operating, the output terminal and the first input contact of the first relay and the second relay are connected to each other.
A communication relay device characterized in that, when the relay processing unit is not operating, the output terminal and the second input contact of the first relay and the second relay are connected to each other. A communication monitoring unit that monitors the presence or absence of communication between the host device and the control device,
When the communication monitoring unit determines that there is no communication, the operation of switching between the connection of the host device and the control device to the first communication path and the interconnection of the host device and the control device is performed. The communication relay device according to claim 1, further comprising a switching control unit that controls the communication path switching unit. A priority setting unit for setting a priority for a request from the data management device to the control device and a request from the host device to the control device is further provided.
The communication relay device according to claim 1 or 2, wherein the relay processing unit transmits a request from the data management device to the control device according to the set priority. Further provided with a baud rate setting unit for setting the baud rate of communication with the control device to a high-speed baud rate higher than the standard baud rate.
The communication relay device according to any one of claims 1 to 3, wherein the relay processing unit performs communication with the control device at the set high-speed baud rate. The communication relay device according to any one of claims 1 to 4, wherein the relay processing unit individually performs communication processing for the host device and communication processing for the control device. When the size of the request from the data management device to the control device exceeds a predetermined value, a request dividing unit for dividing the request into a predetermined size is further provided.
The relay processing unit is divided into requests from the data management device during a period in which a series of processes of the request from the host device and the response of the control device to the host device in response to the request are not performed. The communication relay device according to claim 5, wherein the data is transmitted to the control device.

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