JP7745241B2 - Slave device, communication system, and control method and program for slave device - Google Patents

Description

The present invention relates to a slave device, a communication system, a control method for a slave device, and a program.

Modbus (registered trademark) TCP is a master-slave communication protocol developed by Modicon for programmable logic controllers (PLCs) that allows the serial communication protocol to be used on TCP/IP.

Patent Document 1 discloses technology for exchanging data between a master device and a slave device in accordance with this type of communication protocol. Specifically, in Patent Document 1, the master device transmits a request signal to the slave device, and the slave device transmits data stored in its memory unit to the master device in response to the request signal from the master device. As a result, the master device stores the data from the slave device in its memory unit.

JP 2017-46250 A

However, with the above-mentioned communication protocol, if the data storage methods used by the master device and slave device differ, data cannot be exchanged properly.

The present invention was made in consideration of these issues, and its purpose is to provide a slave device, a communication system, a control method for a slave device, and a program that enable appropriate data exchange between a master device and a slave device.

To achieve the above object, one aspect of the present invention provides a slave device that communicates with a master device and a machine in accordance with a master-slave communication protocol, and includes an acquisition unit that acquires first data related to the machine from the machine, a control unit that stores the first data acquired by the acquisition unit in a memory unit based on a predetermined data storage method that is set commonly between the master device and the slave device, and a communication unit that transmits the first data stored in the memory unit to the master device in response to a request from the master device.

According to this aspect, the control unit stores the first data acquired by the acquisition unit in the memory unit based on a predetermined data storage method that is set in common between the master device and the slave device. This allows the master device and the slave device to share the predetermined data storage method, allowing the first data to be exchanged appropriately between the master device and the slave device.

For example, if only the slave device, of the master device and the slave device, has previously acquired second data indicating the specified data storage method, the communication unit may be configured to transmit the second data to the master device before transmitting the first data.

According to this aspect, even if only the slave device of the master and slave devices has previously acquired the second data, the slave device can transmit the second data to the master device, allowing the master and slave devices to share a predetermined data storage method.

For example, if only the master device of the master device and the slave device has previously acquired second data indicating the specified data storage method, the communication unit may be configured to receive the second data from the master device before the control unit stores the first data in the memory unit.

According to this aspect, even if only the master device has previously acquired the second data, the master device can transmit the second data to the slave device, allowing the master device and slave device to share a predetermined data storage method.

For example, the specified data storage method may be configured to include at least one of the following for the first data: (i) the position of the decimal point, (ii) the maximum number of characters, and (iii) the type of endianness.

According to this aspect, when the first data is a decimal number, a character, or the like, the first data can be appropriately exchanged between the master device and the slave device.

For example, the communication protocol may be configured to be Modbus (registered trademark) TCP.

According to this aspect, Modbus TCP can be applied as a master-slave communication protocol.

Furthermore, one aspect of the present invention provides a communication system comprising a master device, a machine, and a slave device that communicates with the master device and the machine in accordance with a master-slave communication protocol, wherein the slave device has an acquisition unit that acquires data related to the machine from the machine, a first control unit that stores the data acquired by the acquisition unit in a first memory unit based on a predetermined data storage method commonly set between the master device and the slave device, and a first communication unit that transmits the data stored in the first memory unit to the master device in response to a request from the master device, and the master device has a second communication unit that receives the data from the slave device and a second control unit that stores the data received by the second communication unit in a second memory unit based on the predetermined data storage method.

According to this aspect, the first control unit stores the data acquired by the acquisition unit in the first memory unit based on a predetermined data storage method that is set in common between the master device and the slave device. This allows the master device and the slave device to share the predetermined data storage method, enabling appropriate data exchange between the master device and the slave device.

Furthermore, a control method for a slave device according to one aspect of the present invention is a control method for a slave device that communicates with each of a master device and a machine in accordance with a master-slave communication protocol, and includes the steps of: (a) acquiring data related to the machine from the machine; (b) storing the data acquired in (a) in a memory unit based on a predetermined data storage method commonly set between the master device and the slave device; and (c) transmitting the data stored in the memory unit to the master device in response to a request from the master device.

According to this aspect, acquired data is stored in the memory unit based on a predetermined data storage method that is set in common between the master device and the slave device. This allows the master device and the slave device to share the predetermined data storage method, enabling appropriate data exchange between the master device and the slave device.

Furthermore, a program according to one aspect of the present invention causes a computer to execute the above-described slave device control method.

According to one aspect of the present invention, a slave device can properly exchange data between a master device and a slave device.

1 is a block diagram showing an overview of a communication system according to an embodiment; FIG. 2 is a block diagram showing a functional configuration of a slave device according to an embodiment. FIG. 10 is a diagram illustrating an example of machine data stored in a storage unit of a slave device according to an embodiment. FIG. 2 is a block diagram showing a functional configuration of a master device according to an embodiment. 10 is a flowchart showing the flow of operations of the slave device according to the embodiment. 10 is a flowchart illustrating a flow of operations of the master device according to the embodiment. 10 is a flowchart showing the flow of operations of a slave device according to a modified example of the embodiment.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, components that are not recited in the independent claims will be described as optional components.

(Embodiment)
[1. Overview of the communication system]
First, an overview of a communication system 2 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a block diagram showing an overview of a communication system 2 according to an embodiment.

As shown in FIG. 1, communication system 2 includes a slave device 4, a machine 6, and a master device 8. In this embodiment, communication system 2 is a communication system established, for example, within a factory.

In this embodiment, the communication system 2 includes one machine 6, but is not limited to this and may include multiple machines 6. In this embodiment, the communication system 2 includes one master device 8, but is not limited to this and may include multiple master devices 8.

The slave device 4 and the machine 6 are connected via a communication line 10. The communication line 10 is capable of communication using a communication protocol such as Ethernet (registered trademark), IP (Internet Protocol), or RS-232C (serial communication). The communication realized by the communication line 10 may be wired communication or wireless communication. Specifically, the communication line 10 is constructed using, for example, a wired network consisting of a wired LAN (Local Area Network), a wireless network conforming to the IEEE 802.11 standard, or a wired cable for local connection.

The slave device 4 and master device 8 are connected via a network 12. Communication realized over the network 12 may be wired or wireless. Specifically, the network 12 is constructed, for example, as a wired network built using a wired LAN, or as a wireless network conforming to the IEEE 802.11 standard.

Slave device 4 is a server device that communicates with each of machine 6 and master device 8 according to a master-slave communication protocol. More specifically, slave device 4 is a relay device that relays various data between machine 6 and master device 8 according to the master-slave communication protocol. An example of a master-slave communication protocol is Modbus TCP.

Machine 6 is, for example, a lathe, drill press, milling machine, laser processing machine, welding machine, or other machine tool used to perform predetermined processing on a workpiece. Note that machine 6 is not limited to machine tools, and may also be various types of industrial machinery, such as an industrial robot or measuring machine.

The machine 6 has sensors (not shown) for detecting the state of the machine 6. The sensors include, for example, a temperature sensor for detecting the temperature of the machine 6 and a camera sensor for detecting damage to parts of the machine 6. Based on the detection results of the sensors, the machine 6 transmits data about the machine 6 (hereinafter referred to as "machine data") (an example of first data) to the slave device 4 via the communication line 10. Note that the machine data is not limited to data based on the detection results of the sensors, and may be, for example, data indicating letters and/or numbers for identifying each part of the machine 6.

The master device 8 is a client device that communicates with the slave devices 4 according to the master-slave communication protocol described above, and is, for example, a terminal device such as a personal computer operated by the user 14. The master device 8 acquires machine data from the slave devices 4 via the network 12 and presents the acquired machine data to the user 14. Note that the master device 8 is not limited to being operated by the user 14, and may also be operated by, for example, an administrator of the communication system 2. More specifically, the administrator of the communication system 2 may remotely operate the master device 8 within the factory, for example, from outside the factory using an external network.

2. Functional configuration of slave device
The functional configuration of the slave unit 4 according to the embodiment will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a block diagram showing the functional configuration of the slave unit 4 according to the embodiment. Fig. 3 is a diagram showing an example of machine data stored in the storage unit 20 of the slave unit 4 according to the embodiment.

As shown in FIG. 2, the slave device 4 includes an acquisition unit 16, a control unit 18 (an example of a first control unit), a memory unit 20 (an example of a first memory unit), and a communication unit 22 (an example of a first communication unit).

The acquisition unit 16 acquires machine data from the machine 6 via the communication line 10 (see Figure 1), for example, at a predetermined interval. The acquisition unit 16 outputs the acquired machine data to the control unit 18. Note that the predetermined interval is set as appropriate, for example, by an administrator of the communication system 2 using a setting tool (not shown) or the like.

The control unit 18 stores (memorizes) the machine data acquired by the acquisition unit 16 in the memory unit 20 based on a predetermined data storage method set in common between the master device 8 and the slave device 4. Here, the predetermined data storage method includes at least one of the following for the machine data acquired by the acquisition unit 16: (i) the decimal point position, (ii) the maximum number of characters, and (iii) the endian type (big endian or little endian).

The storage unit 20 is a memory for storing various types of data. Specifically, the control unit 18 stores machine data such as that shown in FIG. 3 in the storage unit 20. In the example shown in FIG. 3, addresses (e.g., Modbus addresses) are stored in the storage unit 20 in association with the machine data. For example, address "40001" stores machine data "ab" consisting of characters. Address "40002" stores machine data "c" consisting of characters. Address "40003" stores machine data "0x1000" consisting of a hexadecimal integer. Address "40004" stores machine data "123.456" consisting of a decimal fraction.

In addition, data indicating the above-mentioned specified data storage method (hereinafter referred to as "storage method data") (an example of second data) is pre-stored in the storage unit 20. Note that the storage method data is stored in the storage unit 20, for example, by an administrator of the communication system 2 setting it on a specified website or by importing a CSV file.

The communication unit 22 transmits and receives various data to and from the master device 8 via the network 12 (see Figure 1). Specifically, the communication unit 22 receives a request signal from the master device 8. In addition, the communication unit 22 transmits machine data stored in the memory unit 20 to the master device 8 as a response to the received request signal. In addition, the communication unit 22 transmits storage method data stored in the memory unit 20 to the master device 8.

3. Functional configuration of the master device
The functional configuration of the master device 8 according to the embodiment will be described with reference to Fig. 4. Fig. 4 is a block diagram showing the functional configuration of the master device 8 according to the embodiment.

As shown in FIG. 4, the master device 8 includes a communication unit 24 (an example of a second communication unit), a control unit 26 (an example of a second control unit), and a memory unit 28 (an example of a second memory unit).

The communication unit 24 transmits and receives various data to and from the slave device 4 via the network 12 (see Figure 1). Specifically, the communication unit 24 transmits a request signal to the slave device 4 to request that the slave device 4 transmit machine data. The communication unit 24 also receives machine data transmitted from the slave device 4 in response to the request signal. The communication unit 24 also receives storage method data from the slave device 4.

The control unit 26 retains (stores) the machine data received by the communication unit 24 in the memory unit 28 based on the above-mentioned predetermined data storage method commonly set between the master device 8 and the slave device 4. The control unit 26 also retains the storage method data received by the communication unit 24 in the memory unit 28.

The storage unit 28 is a memory for storing various data. Specifically, the storage unit 28 stores machine data and storage method data stored by the control unit 26.

4. Operation of the communication system
[4-1. Operation of Slave Device]
Next, the operation of the slave device 4 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the flow of the operation of the slave device 4 according to the embodiment.

The following describes a case where only the slave device 4, out of the master device 8 and the slave device 4, has acquired storage method data in advance.

As shown in FIG. 5, the acquisition unit 16 acquires machine data from the machine 6 via the communication line 10 (S101). The control unit 18 stores the machine data acquired by the acquisition unit 16 in the memory unit 20 based on the above-mentioned predetermined data storage method commonly set between the master device 8 and the slave device 4, as follows:

First, the control unit 18 determines whether the machine data is a decimal based on the data storage method stored in the memory unit 20 (S102). If the machine data is not a decimal (NO in S102), the process proceeds to step S104, described below. On the other hand, if the machine data is a decimal (YES in S102), the control unit 18 adjusts the position of the decimal point in the machine data (S103). For example, if the machine data is a decimal "123.456," the control unit 18 adjusts the position of the decimal point in the machine data by separating the machine data into data indicating the integer "123456" excluding the decimal point, and data indicating the position of the decimal point. Note that this position of the decimal point is the same as the position of the decimal point indicated by the storage method data stored in the memory unit 20, for example, "the third position from the lowest digit."

After step S103, or if step S102 is NO, the control unit 18 determines whether the machine data is text based on the data storage method stored in the memory unit 20 (S104). If the machine data is not text (NO in S104), the process proceeds to step S107, described below. On the other hand, if the machine data is text (YES in S104), the control unit 18 determines whether the number of characters in the machine data exceeds the maximum number of characters based on the storage method data stored in the memory unit 20 (S105). The maximum number of characters is the maximum number of characters indicated by the storage method data stored in the memory unit 20, and is, for example, "3."

If the number of characters in the machine data does not exceed the maximum number of characters (NO in S105), the process proceeds to step S107, which will be described later. On the other hand, if the number of characters in the machine data exceeds the maximum number of characters (YES in S105), the control unit 18 adjusts the number of characters in the machine data (S106). For example, if the maximum number of characters is "3" and the machine data acquired by the acquisition unit 16 is "abcde," which has five characters, the control unit 18 adjusts the number of characters in the machine data by adjusting the machine data to "abc," which has three characters.

After step S106, or if the answer is NO in steps S104 and S105, the control unit 18 determines the type of endian indicated by the storage method data stored in the memory unit 20 (S107).

If the endian type is big endian ("big endian" in S107), the control unit 18 stores the machine data in the memory unit 20 as big endian (S108). For example, if the machine data is the characters "abc" and the endian type is big endian, the control unit 18 stores the machine data in the memory unit 20 as "abc".

On the other hand, if the endian type is little endian ("little endian" in S107), the control unit 18 stores the machine data in the memory unit 20 as little endian (S109). For example, if the machine data is the characters "abc" and the endian type is little endian, the control unit 18 stores the machine data in the memory unit 20 as "cba".

[4-2. Operation of the Master Device]
Next, the operation of the master device 8 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing the flow of the operation of the master device 8 according to the embodiment.

The following describes a case where only the slave device 4, out of the master device 8 and the slave device 4, has acquired the storage method data in advance. The communication unit 22 of the slave device 4 transmits the storage method data to the master device 8 in advance before transmitting the machine data to the master device 8.

The communication unit 24 receives the storage method data from the slave device 4 (S201), and the control unit 26 stores the received storage method data in the memory unit 28. As a result, the storage method data indicating the specified data storage method is shared between the master device 8 and the slave device 4.

The communication unit 24 transmits a request signal to the slave device 4 to request that the slave device 4 transmit machine data (S202). The communication unit 24 then receives the machine data transmitted from the slave device 4 in response to the request signal (S203).

The control unit 26 converts the endianness preset in the master device 8 according to the type of endianness indicated by the storage method data held in the memory unit 28 (S204). For example, if the type of endianness indicated by the storage method data is big endianness and the type of endianness preset in the master device 8 is little endianness, the control unit 26 converts the little endianness preset in the master device 8 to big endianness.

The control unit 26 determines whether the machine data is text (S205). If the machine data is text (YES in S205), the control unit 26 stores the machine data in the memory unit 28 (S207). On the other hand, if the machine data is not text (NO in S205), the control unit 26 determines whether the machine data includes the position of a decimal point (S206).

If the machine data does not include the position of a decimal point (NO in S206), the control unit 26 stores the machine data in the memory unit 28 (S207). On the other hand, if the machine data includes the position of a decimal point (YES in S206), the control unit 26 stores the machine data in the memory unit 28 as an integer excluding the decimal point (S208). At this time, the control unit 26 can confirm the position of the decimal point based on the storage method data stored in the memory unit 28.

In this way, the master device 8 can analyze the machine data stored in the memory unit 28 based on the storage method data shared with the slave device 4.

5. Effects
In conventional communication systems, the master device and slave devices have different data storage methods, which makes it difficult to exchange data properly. For example, if a slave device stores the characters "abc" in its memory as machine data, the master device may store the machine data from the slave device as "cba" in its memory because the master device does not share the same endian type with the slave device.

In contrast, in this embodiment, storage method data indicating a predetermined data storage method is shared between the master device 8 and slave device 4. As a result, if, for example, slave device 4 stores the characters "abc" as machine data in memory unit 20, the master device 8 can appropriately store the machine data from slave device 4 as "abc" in memory unit 28 because the endian type is shared between master device 8 and slave device 4. As a result, machine data can be exchanged appropriately between master device 8 and slave device 4.

6. Modifications
Next, the operation of the slave device 4 according to the modified embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the flow of the operation of the slave device 4 according to the modified embodiment. Note that in the flowchart of Fig. 7, the same steps as those in the flowchart of Fig. 5 are assigned the same step numbers, and their description will be omitted.

In this modified example, it is assumed that, of the master device 8 and the slave device 4, only the master device 8 has acquired storage method data in advance. If the communication unit 22 receives storage method data from the master device 8 (YES in S301), the control unit 18 stores the received storage method data in the memory unit 20. Note that, if the communication unit 22 does not receive storage method data from the master device 8 (NO in S301), the process returns to step S301.

After step S301, steps S101 to S109 are executed, similar to the flowchart shown in Figure 5 above.

Therefore, in this modified example, even if only the master device 8 of the master device 8 and the slave device 4 has acquired the storage method data in advance, the master device 8 can transmit the storage method data to the slave device 4, thereby allowing the storage method data to be shared between the master device 8 and the slave device 4. In this case, the communication unit 22 of the slave device 4 receives the storage method data from the master device 8 before storing the machine data in the memory unit 20.

In this modified example, for example, when a new slave device 4 is added (introduced) to the communication system 2, the slave device 4 can obtain storage method data from the master device 8, eliminating the need for the administrator to store storage method data in the newly added slave device 4, improving convenience for the administrator.

(Other variations, etc.)
Although the slave device of the present invention has been described above based on the above embodiment, the present invention is not limited to the above embodiment. The present invention also includes modifications that can be made to the above embodiment by those skilled in the art, and other modifications that can be realized by arbitrarily combining the components of the above embodiment.

In the above embodiment, the master-slave communication protocol was Modbus TCP, but this is not limited to this and any other master-slave communication protocol may be used.

In the above embodiment, the specified data storage method includes at least one of the following: (i) decimal point position, (ii) maximum number of characters, and (iii) endian type of machine data. However, this is not limited to this and may include any other data storage method.

In the above embodiments, each component may be configured with dedicated hardware, or may be realized by executing a software program appropriate for that component. Each component may also be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

The present invention can be applied to, for example, a slave device that communicates with a machine and a master device according to a master-slave communication protocol.

2 Communication system 4 Slave device 6 Machine 8 Master device 10 Communication line 12 Network 14 User 16 Acquisition unit 18, 26 Control unit 20, 28 Storage unit 22, 24 Communication unit

Claims (6)

A slave device that communicates with each of a master device and a machine according to a master-slave communication protocol,
an acquisition unit that acquires first data related to the machine from the machine;
a control unit that stores the first data acquired by the acquisition unit in a storage unit based on second data indicating a predetermined data storage method that is set in common between the master device and the slave device;
a communication unit that transmits the first data stored in the storage unit to the master device in response to a request from the master device ,
when the slave device of the master device and the slave device has previously acquired the second data and the master device has not previously acquired the second data, the communication unit transmits the second data to the master device before transmitting the first data;
When the master device of the master device and the slave device has previously acquired the second data and the slave device has not previously acquired the second data, the communication unit receives the second data from the master device before the control unit stores the first data in the storage unit.
Slave device. The slave device according to claim 1 , wherein the predetermined data storage method includes at least one of (i) a decimal point position, (ii) a maximum number of characters, and (iii) an endian type of the first data. The slave device according to claim 1 or 2 , wherein the communication protocol is Modbus (registered trademark) TCP. A communication system comprising a master device, a machine, and a slave device that communicates with the master device and the machine according to a master-slave communication protocol,
The slave device
an acquisition unit that acquires first data related to the machine from the machine;
a first control unit that stores the first data acquired by the acquisition unit in a first storage unit based on second data indicating a predetermined data storage method that is set in common between the master device and the slave device;
a first communication unit that transmits the first data stored in the first storage unit to the master device in response to a request from the master device;
The master device
a second communication unit that receives the first data from the slave device;
a second control unit that stores the first data received by the second communication unit in a second storage unit based on the predetermined data storage method ,
when the slave device of the master device and the slave device has previously acquired the second data and the master device has not previously acquired the second data, the first communication unit transmits the second data to the master device before transmitting the first data;
When the master device of the master device and the slave device has previously acquired the second data and the slave device has not previously acquired the second data, the first communication unit receives the second data from the master device before the first control unit stores the first data in the first storage unit.
Communication system. A control method for a slave device that communicates with a master device and a machine according to a master-slave communication protocol, comprising:
(a) obtaining first data relating to the machine from the machine;
(b) storing the first data acquired in (a) in a storage unit based on second data indicating a predetermined data storage method commonly set between the master device and the slave device;
(c) transmitting the first data stored in the storage unit to the master device in response to a request from the master device;
(d) (i) if the slave device of the master device and the slave device has acquired the second data in advance and the master device has not acquired the second data in advance, transmitting the second data to the master device before transmitting the first data in (c); and (ii) if the master device of the master device and the slave device has acquired the second data in advance and the slave device has not acquired the second data in advance, receiving the second data from the master device before storing the first data in the memory unit in (b) . A program that causes a computer to execute the slave device control method according to claim 5 .