Slave device, communication system, and control method and program for slave device

Abstract

To provide a slave device capable of appropriately exchanging data between a master device and the slave device.SOLUTION: A slave device 4 communicates with each of a master device 8 and a machine 6 according to a master-slave communication protocol. The slave device 4 comprises: an acquisition unit 16 that acquires data related to the machine 6 from the machine 6; a control unit 18 that stores the data acquired by the acquisition unit 16 in a storage unit 20 based on a predetermined data storage method which is commonly set between the master device 8 and the slave device 4; and a communication unit 22 that transmits data stored in the storage unit 20 to the master device 8 in response to a request from the master device 8.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a slave device, a communication system, a control method for a slave device, and a program. [Background technology]

[0002] Modbus (registered trademark) TCP is a master-slave communication protocol for using a serial communication protocol developed by Modicon for programmable logic controllers (PLCs) on TCP / IP.

[0003] Patent Document 1 discloses a technique for exchanging data between a master device and a slave device according to 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 a memory unit of the slave device to the master device as a 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-46250 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the above-mentioned communication protocol, if the master device and the slave device have different data storage methods, the data cannot be exchanged appropriately.

[0006] The present invention has been made in view of the above problems, 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. [Means for solving the problem]

[0007] In order to achieve the above object, a slave device according to one embodiment of the present invention is a slave device that communicates with each of 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.

[0008] According to this aspect, the control unit stores the first data acquired by the acquisition unit in the storage unit based on a predetermined data storage method that is set in common between the master device and the slave device. This allows the predetermined data storage method to be shared between the master device and the slave device, making it possible to appropriately exchange the first data between the master device and the slave device.

[0009] For example, if only the slave device out of the master device and the slave device has previously acquired second data indicating the predetermined data storage method, the communication unit may be configured to transmit the second data to the master device before transmitting the first data.

[0010] According to this aspect, even if only the slave device among the master device and the slave device has acquired the second data in advance, the slave device can transmit the second data to the master device, thereby allowing the master device and the slave device to share a predetermined data storage method.

[0011] For example, if only the master device of the master device and the slave device has previously acquired second data indicating the predetermined 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.

[0012] According to this aspect, even if only the master device among the master device and the slave device has acquired the second data in advance, the master device can transmit the second data to the slave device, thereby allowing the master device and the slave device to share a predetermined data storage method.

[0013] For example, the predetermined data storage method may be configured to include at least one of (i) the position of a decimal point, (ii) the maximum number of characters, and (iii) the type of endian of the first data.

[0014] According to this aspect, when the first data is a decimal number or a character, the first data can be appropriately exchanged between the master device and the slave device.

[0015] For example, the communication protocol may be configured to be Modbus TCP.

[0016] According to this embodiment, Modbus TCP can be applied as a master-slave communication protocol.

[0017] Moreover, 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 each of the machines 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 that is set in common 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.

[0018] According to this aspect, the first control unit stores the data acquired by the acquisition unit in the first storage unit based on a predetermined data storage method that is set in common between the master device and the slave device. This allows the predetermined data storage method to be shared between the master device and the slave device, thereby enabling appropriate data exchange between the master device and the slave device.

[0019] 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 that is set in common 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.

[0020] According to this aspect, the acquired data is stored in the storage unit based on a predetermined data storage method that is set in common between the master device and the slave device. This allows the predetermined data storage method to be shared between the master device and the slave device, enabling appropriate data exchange between the master device and the slave device.

[0021] A program according to one aspect of the present invention causes a computer to execute the above-described slave device control method. [Effects of the Invention]

[0022] According to the slave device and the like according to one aspect of the present invention, data can be exchanged appropriately between the master device and the slave device. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a block diagram showing an overview of a communication system according to an embodiment; [Figure 2] FIG. 2 is a block diagram showing a functional configuration of a slave device according to an embodiment. [Figure 3] FIG. 10 is a diagram illustrating an example of machine data stored in a storage unit of a slave device according to an embodiment. [Figure 4] FIG. 2 is a block diagram showing a functional configuration of a master device according to an embodiment. [Figure 5] 10 is a flowchart showing the flow of operations of the slave device according to the embodiment. [Figure 6] 10 is a flowchart illustrating a flow of operations of the master device according to the embodiment. [Figure 7] 10 is a flowchart showing the flow of operations of a slave device according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of the present invention will be described in detail 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 forms, steps, step order, etc. 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 not recited in independent claims will be described as optional components.

[0025] (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.

[0026] 1, the communication system 2 includes a slave device 4, a machine 6, and a master device 8. In this embodiment, the communication system 2 is a communication system established in a factory, for example.

[0027] 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.

[0028] The slave device 4 and the machine 6 are connected via a communication line 10. The communication line 10 is a communication line capable of communicating 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 configured by a wired LAN (Local Area Network), a wireless network conforming to the IEEE802.11 standard, or a wired cable for local connection.

[0029] The slave device 4 and the master device 8 are connected via a network 12. Communication realized through the network 12 may be wired communication or wireless communication. Specifically, the network 12 is constructed as a wired network based on, for example, a wired LAN, or as a wireless network conforming to the IEEE802.11 standard.

[0030] The slave device 4 is a server device for communicating with each of the machine 6 and the master device 8 in accordance with a master-slave communication protocol. More specifically, the slave device 4 is a relay device for relaying various data between the machine 6 and the master device 8 in accordance with the master-slave communication protocol. The master-slave communication protocol is, for example, Modbus TCP.

[0031] The machine 6 is, for example, a lathe, a drill press, a milling machine, a laser processing machine, a welding machine, or any other machine tool for performing predetermined processing on a workpiece. Note that the machine 6 is not limited to a machine tool, and may be, for example, an industrial robot, a measuring machine, or any other industrial machine.

[0032] 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.

[0033] The master device 8 is a client device for communicating with the slave devices 4 in accordance with the above-described master-slave communication protocol, and may be, for example, any of various terminal devices such as a personal computer operated by a 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, for example, by an administrator of the communication system 2. More specifically, the administrator of the communication system 2 may remotely operate the master device 8 in the factory from outside the factory, for example, by using an external network.

[0034] [2. Functional configuration of slave device] The functional configuration of the slave device 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 device 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 device 4 according to the embodiment.

[0035] 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).

[0036] The acquisition unit 16 acquires machine data from the machine 6 via the communication line 10 (see FIG. 1), for example, at a predetermined cycle. The acquisition unit 16 outputs the acquired machine data to the control unit 18. Note that the predetermined cycle is appropriately set, for example, by an administrator of the communication system 2 or the like using a setting tool (not shown) or the like.

[0037] The control unit 18 stores (memorizes) the mechanical 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 (i) the decimal point position, (ii) the maximum number of characters, and (iii) the endian type (big endian or little endian) of the mechanical data acquired by the acquisition unit 16.

[0038] The storage unit 20 is a memory for storing various data. Specifically, the control unit 18 stores, for example, mechanical data as shown in FIG. 3 in the storage unit 20. In the example shown in FIG. 3, addresses (e.g., Modbus addresses) and mechanical data are stored in association with each other in the storage unit 20. For example, mechanical data "ab" consisting of characters is stored in address "40001." Furthermore, mechanical data "c" consisting of characters is stored in address "40002." Furthermore, mechanical data "0x1000" consisting of a hexadecimal integer is stored in address "40003." Furthermore, mechanical data "123.456" consisting of a decimal fraction is stored in address "40004."

[0039] Furthermore, data indicating the predetermined 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 by, for example, an administrator of the communication system 2 setting it on a predetermined website or importing a CSV file.

[0040] The communication unit 22 transmits and receives various data to and from the master device 8 via the network 12 (see FIG. 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 storage 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 storage unit 20 to the master device 8.

[0041] [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.

[0042] 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 storage unit 28 (an example of a second storage unit).

[0043] The communication unit 24 transmits and receives various data to and from the slave device 4 via the network 12 (see FIG. 1). Specifically, the communication unit 24 transmits a request signal to the slave device 4 to request the slave device 4 to transmit machine data. The communication unit 24 also receives the 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.

[0044] The control unit 26 holds (stores) the machine data received by the communication unit 24 in the storage unit 28 based on the above-mentioned predetermined data storage method set in common between the master device 8 and the slave device 4. The control unit 26 also holds the storage method data received by the communication unit 24 in the storage unit 28.

[0045] The storage unit 28 is a memory for storing various data. Specifically, the control unit 26 stores machine data and storage method data in the storage unit 28.

[0046] [4. Operation of communication system] [4-1. Operation of the 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.

[0047] Below, a case will be described in which, of the master device 8 and the slave device 4, only the slave device 4 has acquired the storage method data in advance.

[0048] 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 storage unit 20 based on the above-mentioned predetermined data storage method set in common between the master device 8 and the slave device 4, as follows.

[0049] First, the control unit 18 determines whether the machine data is a decimal number based on the data storage method stored in the memory unit 20 (S102). If the machine data is not a decimal number (NO in S102), the process proceeds to step S104, which will be described later. On the other hand, if the machine data is a decimal number (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 number such as "123.456," the control unit 18 adjusts the position of the decimal point in the machine data by dividing 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, such as "the third position from the lowest digit."

[0050] After step S103, or if step S102 is NO, control unit 18 determines whether the machine data is text based on the data storage method stored in memory unit 20 (S104). If the machine data is not text (NO in S104), the process proceeds to step S107, which will be described later. On the other hand, if the machine data is text (YES in S104), 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 memory unit 20 (S105). The maximum number of characters is the maximum number of characters indicated by the storage method data stored in memory unit 20, and is, for example, "3."

[0051] 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.

[0052] 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 storage unit 20 (S107).

[0053] If the endian type is big endian ("big endian" in S107), the control unit 18 stores the mechanical data in the storage unit 20 as big endian (S108). For example, if the mechanical data is the characters "abc" and the endian type is big endian, the control unit 18 stores the mechanical data in the storage unit 20 as "abc".

[0054] On the other hand, if the endian type is little endian ("little endian" in S107), the control unit 18 stores the mechanical data in little endian format in the storage unit 20 (S109). For example, if the mechanical data is the characters "abc" and the endian type is little endian, the control unit 18 stores the mechanical data in the storage unit 20 as "cba".

[0055] [4-2. Master device operation] 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.

[0056] 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.

[0057] 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 predetermined data storage method is shared between the master device 8 and the slave device 4.

[0058] The communication unit 24 transmits a request signal to the slave device 4 to request the slave device 4 to transmit mechanical data (S202). Then, the communication unit 24 receives the mechanical data transmitted from the slave device 4 in response to the request signal (S203).

[0059] The control unit 26 converts the endian that is preset in the master device 8 in accordance with the type of endian indicated by the storage method data held in the storage unit 28 (S204). For example, if the type of endian indicated by the storage method data is big endian and the type of endian that is preset in the master device 8 is little endian, the control unit 26 converts the little endian that is preset in the master device 8 to big endian.

[0060] Control unit 26 determines whether the machine data is text (S205). If the machine data is text (YES in S205), control unit 26 stores the machine data in storage unit 28 (S207). On the other hand, if the machine data is not text (NO in S205), control unit 26 determines whether the machine data includes a decimal point position (S206).

[0061] 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 storage 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 as an integer excluding the decimal point in the storage unit 28 (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 storage unit 28.

[0062] In this way, the master device 8 can analyze the machine data stored in the storage unit 28 based on the storage method data shared with the slave device 4.

[0063] [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.

[0064] In contrast to this, in this embodiment, storage method data indicating a predetermined data storage method is shared in advance between the master device 8 and the slave device 4. As a result, if, for example, the slave device 4 stores the characters "abc" as mechanical data in the storage unit 20, the master device 8 can appropriately store the mechanical data from the slave device 4 as "abc" in the storage unit 28 because the endian type is shared between the master device 8 and the slave device 4. As a result, mechanical data can be exchanged appropriately between the master device 8 and the slave device 4.

[0065] [6. Modifications] Next, the operation of the slave device 4 according to the modified example of the 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 example of the 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.

[0066] In this modification, 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. When the communication unit 22 receives the 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. When the communication unit 22 does not receive the storage method data from the master device 8 (NO in S301), the process returns to step S301.

[0067] After step S301, steps S101 to S109 are executed in the same manner as in the flowchart shown in FIG.

[0068] Therefore, in this modification, 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.

[0069] 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 the storage method data from the master device 8, so the administrator does not need to store the storage method data in the newly added slave device 4, thereby improving the convenience for the administrator.

[0070] (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.

[0071] In the above embodiment, the master-slave communication protocol is Modbus TCP, but the present invention is not limited to this and any other master-slave communication protocol may be used.

[0072] In the above embodiment, the specified data storage method includes at least one of (i) the decimal point position, (ii) the maximum number of characters, and (iii) the endian type of the machine data, but is not limited to this and may include any other data storage method.

[0073] In the above-described embodiments, each component may be configured with dedicated hardware, or may be realized by executing a software program suitable for each 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. [Industrial Applicability]

[0074] 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. [Explanation of symbols]

[0075] 2. Communication Systems 4 Slave Devices 6 machines 8 Master Device 10 Communication lines 12 Network 14 users 16 Acquisition Department 18,26 Control unit 20,28 Storage part 22,24 Communications Department

Claims

1. 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.

2. The predetermined data storage method includes at least one of (i) the position of a decimal point, (ii) the maximum number of characters, and (iii) the type of endian of the first data. The slave device according to claim 1 .

3. The communication protocol is Modbus TCP.

3. The slave device according to claim 1 or 2.

4. 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.

5. 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 storage unit in (b). A method for controlling a slave device.

6. A method for controlling a slave device according to claim 5 is executed by a computer. program.

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