Control device
The control device addresses the challenges of managing tag variables across distributed control systems by automating the writing of tag variables in other control devices, reducing the need for manual updates and minimizing data communication, thus enhancing operational efficiency and preventing incompatibility issues.
Patent Information
- Application Number
- JP2023198567
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-11-22
- Publication Date
- 2025-06-03
AI Technical Summary
In distributed control systems, managing tag variables across different control devices is laborious and prone to incompatibility issues due to the need for frequent updates when equipment is added, deleted, or modified. Additionally, the constant communication between control devices leads to a significant amount of data transmission.
A control device that includes a user program execution unit to generate write information for tag variables in other control devices, a transmission information registration unit to register this information, and a synchronization processing unit to transmit it at predetermined timings, allowing for efficient writing to tag variables without requiring explicit management of physical addresses or dedicated communication spaces.
This solution reduces the burden of constructing user programs and managing communication spaces, minimizes data communication, and prevents incompatibility issues by automating the transmission of write information and eliminating the need for manual updates of management materials.
Smart Images
Figure 2025084571000001_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present invention relate to a control device.
Background Art
[0002] In a control device used in a distributed control system (also referred to as a DCS: Distributed Control System), a user program is constructed using tag variables with arbitrarily assigned names, and control operations such as PID control are performed.
[0003] It is easy when performing a control operation using tag variables within its own control device, but there are cases where tag variables of other control devices are referred to or written to.
[0004] When writing, the user creates a user program for both the control device on the side where writing is performed (hereinafter also referred to as the transmission side) and the side where writing is done (hereinafter also referred to as the reception side), and causes regular communication between the control device on the transmission side and the control device on the reception side.
Summary of the Invention
Problems to be Solved by the Invention
[0005] When performing the above-described regular communication, the user constructs a user program by organizing the relationship between the transmission side and the reception side using management materials and the like. However, after the start of operation of the distributed control system, when equipment is added, deleted, or modified, etc., the management materials are not updated, and as a result, the user program may be constructed with incorrect information, leading to incompatibility. Also, the user needs to update the management materials every time equipment is added, deleted, or modified, etc., which is a very laborious and burdensome task in terms of construction.
[0006] In addition, since data transmission and reception are constantly performed between the control device on the transmission side and the control device on the reception side, a large amount of communication occurs.
[0007] Therefore, an embodiment of the present invention provides a control device that can write to tag variables, similar to its own control device, even in other control devices.
Means for Solving the Problems
[0008] According to one embodiment, a control device includes a user program execution unit that executes a user program for generating write information including a physical address and a write value in another control device serving as a write destination based on tag information indicating an element name of a tag variable structure specified by a user. The control device further includes a transmission information registration unit that accepts registration of the write information based on execution of the user program. The control device further includes a synchronization processing unit that transmits the write information accepted for registration by the transmission information registration unit to the other control device at a predetermined first timing.
Brief Description of the Drawings
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Modes for Carrying Out the Invention
[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. These embodiments do not limit the present invention. The drawings are schematic or conceptual, and the ratios of each part are not necessarily the same as those in reality. In the specification and the drawings, the same reference numerals are given to the same elements as those described above with respect to the previous drawings, and detailed descriptions thereof are omitted as appropriate.
[0011] FIG. 1 is an example of an overall configuration diagram of the distributed control system 10 in this embodiment.
[0012] The distributed control system 10 is, for example, a system that realizes process automation or factory automation in a plant. The distributed control system 10 includes a control device 1, a monitoring device 2, a tool 3, an Ethernet hub 4, and an I / O device 5. In this example, for the sake of explanation, unless there is a need for particular distinction, the control device 1 on the transmission side is represented as the control device 1a, and the control device 1 on the reception side is represented as the control device 1b. Also, hereinafter, for the explanation of specific examples, the name of the control device 1a may also be represented as Stn1, and the name of the control device 2a may also be represented as Stn2.
[0013] Also, in this example, the distributed control system 10 shows a configuration with two control devices 1, but the configuration of the distributed control system 10 is not limited to this. The distributed control system 10 may be provided with any number of control devices 1. Also, each control device 1 may be in a relationship of a master station and a slave station, or each control device may not have a master station and slave station relationship and may operate at the same level in cooperation.
[0014] The control device 1 is a device that performs various controls such as state monitoring and automatic control of facilities in the plant. For example, the control device 1 corresponds to an industrial controller. The control device 1 performs control operations such as PID control according to a user program created by the user. In the present embodiment, when performing control operations, the control device 1a refers to tag variables held in its own control device 1a, refers to tag variables in the control device 1b, or writes tag variables to the control device 1b. The configuration of the control device 1 and tag variables will be described later.
[0015] The monitoring device 2 is a device for grasping the control state of facilities in the plant. The monitoring device 2, for example, displays information collected from the control device 1 on a display.
[0016] The tool 3 is a device for creating and maintaining a user program that is the control program of the control device 1. The user creates a user program via the user interface of the tool 3 and downloads it to the control device 1. Also, although details will be described later, the tool 3 has a tag information database in which the tag name of the tag variable, the name of the control device 1 in which the tag variable is included, and the physical address assigned to the tag variable are associated.
[0017] The Ethernet hub 4 is a device for connecting the control device 1, the monitoring device 2, and the tool 3 to the Ethernet 20. Descriptions of other network facilities are omitted. Also, the download of the user program from the tool 3 to the control device 1 and the communication between the control device 1a and the control device 1b are performed via the Ethernet 20. In the present embodiment, an example in which the control device 1, the monitoring device 2, and the tool 3 communicate via the Ethernet 20 will be described, but the network between these devices may be constructed using a public line such as an Internet line.
[0018] The I / O device 5 transmits the information collected from the sensors of the device to be controlled (not shown) to the control device 1, and also transmits an operation signal output from the control device 1 for operating the device to be controlled. In this example, only the I / O device 5 connected to the control device 1a is shown, and since the I / O device 5 connected to the control device 1b has the same operation, the description thereof is omitted. Further, the control device 1 and the I / O device 5 are connected by an I / O network 30, and dedicated communication corresponding to the I / O device 5 is performed.
[0019] Unlike the configuration of the present embodiment, the distributed control system 10 may have a shared memory accessible by the control device 1a and the control device 1b on the Ethernet 20. This shared memory is provided, for example, in a PC (Personal Computer). Further, the shared memory may be provided in the control device 1a, the control device 1b, or a control device 1 different from these.
[0020] FIG. 2 is a diagram for explaining an example of tag variables.
[0021] FIG. 2 shows examples of a tag variable related to an indicator (tag name = STN30_IND001) and a tag variable related to a controller (tag name = STN30_PID001).
[0022] A tag variable (also called a tag instrument) is a collection of variables having a special structure. Further, the tag variable is registered in the control device 1. For example, the tag variable includes parameter information such as a tag name, a type, and an upper limit of a range, and tag data information such as a PV value and an SV value. The parameter information is the content registered by the tool 3. For example, the tag name indicates the name of the tag variable, the type indicates what structure and specifications the tag has, and the upper limit of the range indicates the upper limit of the setting range. Further, the lower limit of the range indicates the lower limit of the setting range. The tag data information is a value that changes moment by moment. The PV value indicates a current value such as a temperature collected from the sensor of the device to be controlled, the SV value indicates a target value such as a set temperature, and the MV value indicates an operation value.
[0023] The user program refers to the information of this tag variable, mainly performs calculations using the PV value and the SV value, and controls the equipment to be controlled in the plant by performing operation outputs to the MV value.
[0024] The tag name is a unique value within the distributed control system 10. For a specific variable in the tag variable, it can be accessed by specifying the tag name and the element name of its structure. For example, in the left example of FIG. 2, if it is the PV value of the tag name = STN30_PID001, the PV value can be referred to by specifying it as STN30_PID001.PV.
[0025] When a tag variable is registered in the control device 1, the monitoring device 2 receives the information via the Ethernet 20, arranges it in an easy-to-view manner, and displays it. For example, for the tag variable with the tag name = STN30_IND001, the monitoring device 2 displays that the PV value is 25.00 according to the values of the range lower limit = 0.00 and the range upper limit = 100.00 as shown on the right side of FIG. 2. Also, for the tag variable with the tag name = STN30_PID001, the monitoring device 2 displays that the PV value is 25.00 and the SV value is 50.00 according to the values of the range lower limit = 0.00 and the range upper limit = 100.00. Also, for the MV value, the monitoring device 2 displays that it is 40.0.
[0026] FIG. 3 is an example of a block diagram of the control device 1 in the present embodiment.
[0027] Since the block diagrams of the control devices 1a and 1b are the same, in the present embodiment, unless otherwise specified, the block diagram will be described as the control device 1. In the following operations, the control device 1a will be described as the transmitting control device 1, and the control device 1b will be described as the receiving control device 1. However, the same operations will be achieved even if the control device 1a and the control device 1b are interchanged.
[0028] The control device 1 includes a user program execution unit 11, a tag variable storage unit 12, a transmission information registration unit 13, a reception information registration unit 14, and a synchronization processing unit 15. When the CPU (Central Processing Unit) in the control device 1 executes the program of the control device 1, the functions of the user program execution unit 11, the tag variable storage unit 12, the transmission information registration unit 13, the reception information registration unit 14, and the synchronization processing unit 15 are realized. The transmission information registration unit 13 and the reception information registration unit 14 are constructed on a main storage device such as a RAM (Random Access Memory), for example. Similarly, the tag variable storage unit 12 is also constructed on the main storage device.
[0029] The tag variable storage unit 12 stores the tag variables used in the control device 1. Each tag variable is assigned and stored at a physical address in the control device 1.
[0030] The user program execution unit 11 executes the above-described user program. In the present embodiment, the control device 1a writes a value to the tag variable of the control device 1b based on the execution of the user program in the user program execution unit 11. The control device 1a has a special instruction word for writing a value to the tag variable of the control device 1b as a user program. When the execution condition of this special instruction word becomes ON and the write value changes, the write information is registered in the transmission information registration unit 13. Also, in this example, the special instruction word is created by the user for each element name of the structure of the tag variable to be written to the control device 1b and is executed in the scan process.
[0031] The transmission information registration unit 13 accepts the registration of the write information based on the execution of the above-described special instruction word. The write information is transmitted to the control device 1b at a predetermined first timing. It is desirable that the write information be transmitted collectively after the execution of all the user programs of the control device 1a has ended. Therefore, the first timing may be, for example, the end of the scan process. Also, the first timing may be, for example, the start of the scan process or during the scan process.
[0032] The reception information registration unit 14 receives the registration of the writing information received from the control device 1a. Also, the writing information is written to the corresponding tag variable at a predetermined second timing. It is desirable that the writing information be written collectively before the user program in the control device 1b is executed. Therefore, the second timing may be, for example, the start time of the scan process. Also, the second timing may be, for example, the end time of the scan process or during the scan process.
[0033] The synchronization processing unit 15 performs the above-described scan process. The writing information registered in the transmission information registration unit 13 is transmitted from the control device 1a to the control device 1b at the first timing by the synchronization processing unit 15 taking synchronization. Also, the writing information registered in the reception information registration unit 14 is written to the corresponding tag variable at the second timing by the synchronization processing unit 15 taking synchronization.
[0034] FIG. 4 is a diagram for explaining the flow at the time of execution of the user program in the present embodiment.
[0035] In FIG. 4, as an example of the user program of the control device 1a, an example is taken and explained in which a special instruction word (TS_REAL) operates to specify a tag variable having the tag name = PID2001 in the control device 1b and write PV value = 12. Also, the special instruction word (TS_REAL) explained in this example is assumed to have been created in advance by the user and downloaded to the control device 1a. Also, in this example, in order to mainly explain the data flow, some functional blocks in the block diagram explained in FIG. 3 are taken and explained.
[0036] In this embodiment, when a special instruction word (TS_REAL) satisfies a predetermined execution condition (EN) and there is a change in the write value (VAL), it generates write information including the name of the control device 1 containing the tag variable to be written (simply referred to as the destination), tag information (TAG) indicating the element name of the structure of the tag variable to be written, the write value (VAL), and the physical address within the control device 1 to be written, and registers it in the transmission queue in the transmission information registration unit 13. In this example, when the execution condition (EN) of the special instruction word (TS_REAL) becomes ON and there is a change in the value of the write value (VAL), in order to write the write value to the tag information (TAG), the write information is registered in the transmission queue. In this example, the special instruction word (TS_REAL) designates the PV value of the tag variable having the tag name = PID2001 as the tag information.
[0037] In this example, the special instruction word (TS_REAL) is created for each tag information (TAG). That is, the special instruction word (TS_REAL) is created for each element name of the structure of the tag variable. Also, the special instruction word (TS_REAL) may be configured to write to a plurality of data information included in one tag variable based on changes in a plurality of write values.
[0038] When creating the special instruction word (TS_REAL), the user does not need to be aware of which physical address the tag variable is assigned to. When the tag information (TAG) is specified by the user, the tool 3 refers to the tag information database and associates which physical address of which control device 1 the tag variable in the tag information (TAG) corresponds to. In this example, the destination and the offset address are associated with the tag name, and this information is stored in the variable of the special instruction word (TS_REAL).
[0039] Based on the operation of the special instruction word (TS_REAL), the write information is registered in the transmission queue. In this example, in the transmission queue, the destination Stn2, the tag information (TAG) PID2001.SV, the write value 12, and the offset address +BBB are registered.
[0040] In this example, the write information registered in the transmission queue is transmitted by the synchronization processing unit 15 via the Ethernet 20 at the end of the scan process of the control device 1a. When transmitting the write information, the control device 1 may use either the unicast or multicast method. In unicast, the control device 1 transmits the write information to the destination registered in the transmission queue (in this case, Stn2). Also, the receiving control device 1 registers the received write information in the reception queue. In multicast, the control device 1 transmits the write information to all other control devices 1 within the distributed control system 10. The received control device 1 checks the destination, and if the write information is addressed to its own control device 1, it registers the write information in the reception queue, and if it is not addressed to its own control device 1, it discards the write information.
[0041] In this example, the write information registered in the reception queue is written into the tag variable at the start of the scan process of the control device 1b by the synchronization processing unit 15. The synchronization processing unit 15 writes to the corresponding write destination from the registered physical address. Since the write information registered in the reception queue is written into the tag variable when performing the synchronization process, in the control device 1b, it is not necessary to construct a user program for writing.
[0042] In this example, the tool 3 refers to the tag information database and associates which physical address of which control device 1 the tag variable in the tag information (TAG) corresponds to. However, as described above, if a configuration using shared memory is adopted, a configuration may be used in which the tag variable in the tag information (TAG) is associated with the physical address in the shared memory serving as the write destination.
[0043] Also, in the case of a configuration using shared memory, the receiving control device 1 may be configured to receive the write information transmitted from a PC or the like having the shared memory and register it in the reception queue.
[0044] FIG. 5 is a diagram showing a configuration example of the tag information database in the present embodiment.
[0045] In this example, in the tag information database, the tag name, Stn number, and offset address are stored in association with each other. The tag names are centrally registered with the tag names used in the control device 1 within the distributed control system 10. The Stn numbers are registered with the names of the respective control devices 1 as numbers like Stn1 and Stn2 described above, and indicate the control device 1 that includes the tag name. Also, in this example, the physical address is registered as the offset address of the tag variable.
[0046] When the number of tags managed within the system increases or decreases due to addition, modification, or removal of controlled devices within the distributed control system 10, the user edits this tag information database. For example, the user edits the tag information database using the software installed in tool 3.
[0047] FIG. 6 is an example of a block diagram of the control device 1 in the comparative example.
[0048] Since the overall configuration diagram of the distributed control system 10 is the same as that in FIG. 1, the description thereof is omitted.
[0049] For the sake of explanation, in the comparative example, the control device 1 on the transmission side is represented as control device 1a', and the control device 1 on the reception side is represented as control device 1b'. Also, hereinafter, for the sake of explanation of specific examples, the name of control device 1a may also be represented as Stn1', and the name of control device 2a may also be represented as Stn2'.
[0050] The control device 1 in the comparative example includes a transmission area 16 and a reception area 17 that perform data transmission between the control device 1a' and the control device 1b', in addition to a user program execution unit 11, a tag variable storage unit 12, and a synchronization processing unit 15. Different from this embodiment, in the comparative example, the transmission area 16 and the reception area 17 are secured as dedicated areas accessible by the user program. Also, the user can freely register variables in the transmission area.
[0051] Also, unlike the present embodiment, in the comparative example, the tool 3 does not have a tag information database. Therefore, in addition to information such as tag variables existing in the distributed control system 10, which control device 1 the tag variables are included in, and the physical addresses assigned to the tag variables, variables for managing the tag variables described later are managed in management documents and the like.
[0052] FIG. 7 is a diagram for explaining the flow during the execution of the user program in the comparative example.
[0053] As described above, in the comparative example, the user can freely register variables in the transmission area 16. In this example, the user declares two variables, PID2001_SV which is a variable for communication and TRG_CNT which is a variable for incrementing the trigger count, via the tool 3. Also, in the reception area 17, the two variables, PID2001_SV and TRG_CNT, defined in the transmission area 16 are accessible.
[0054] When the execution condition is satisfied, the user program of the control device 1a' substitutes the write value (12 in this example) into PID2001_SV in the transmission area. Also, in order to indicate that the writing has been done, the user program increments TRG_CNT in the transmission area.
[0055] The variables in the transmission area 16 are transmitted at a fixed period and received in the reception area 17 of the control device 1b'.
[0056] On the other hand, the control device 1b' operates the user program and constantly monitors the writing in the control device 1a'. When the value of TRG_CNT changes, the user program of the control device 1b' writes the value of PID2001_SV to its corresponding tag variable. In this example, the value 12 is written to the SV value of the tag name PID2001.
[0057] Thus, in the comparative example, dedicated transmission area 16 and reception area 17 are secured for control devices 1a’ and 1b’. Also, in the comparative example, control devices 1a’ and 1b’ require a scan transmission space (in this example, PID2001_SV which is a variable for communication and TRG_CNT which is a variable for trigger count increment) that is constantly transmitted from control device 1a’ to control device 1b’, which is a factor contributing to an increase in the number of transmission packets.
[0058] Also, since only declared variables can be accessed in transmission area 16 and reception area 17, the user needs to define variables corresponding to tag variables (in this example, PID2001_SV which is a variable for communication) and variables indicating the writing timing (in this example, TRG_CNT which is a variable for trigger count increment).
[0059] If the number of tag variables to be written increases, the user will need to add variables to transmission area 16 and reception area 17 accordingly. If the maintenance of these transmission variables cannot be done correctly, it may become a factor for unexpected incompatibility.
[0060] Also, in control device 1b’, it is necessary to construct a user program that monitors reception area 17 and performs writing, which takes a lot of effort in system construction.
[0061] FIG. 8 is an example of a flowchart of the transmission flow of control device 1a in this embodiment.
[0062] In this flowchart, the main flow regarding the writing of tag variables of control device 1 in this embodiment will be described. The description of flows such as periodic mode control processing and self-diagnosis processing during scan processing will be omitted.
[0063] In step S1, the control device 1 is activated by the user turning on the power of the control device 1. After the power is turned on, the CPU in the control device 1 executes the program of the control device 1, thereby realizing the functions of the user program execution unit 11, the tag variable storage unit 12, the transmission information registration unit 13, the reception information registration unit 14, and the synchronization processing unit 15. In step S2, the control device 1 performs initialization processing. In the initialization processing, the control device 1 performs hardware initial diagnosis, hardware initialization, control program diagnosis, variable initialization, and the like.
[0064] Steps S3 to S5 are the flow performed in the scan processing. In step S3, the synchronization processing unit 15 checks whether there is write information registered in the reception queue of the reception information registration unit 14. If there is write information registered in the reception queue, the synchronization processing unit 15 performs writing to the corresponding tag variable as synchronization processing. In step S4, the user program execution unit 11 executes the user program. The above-mentioned special instruction word (TS_REAL) is also executed in this step. In this flow, when the execution condition (EN) is ON and there is a change in the write value (VAL) due to the execution of the special instruction word (TS_REAL), the write value, physical address, etc. are registered as write information in the transmission queue in the transmission information registration unit 13.
[0065] In step S5, the synchronization processing unit 15 checks whether there is write information registered in the transmission queue of the transmission information registration unit 13. If there is write information registered in the transmission queue, the synchronization processing unit 15 transmits the write information. Also, after the end of step S5, it returns to step S3, and steps S3 to S5 are repeated during the next scan processing.
[0066] FIG. 9 is a hardware configuration diagram of the control device 1 in the present embodiment.
[0067] The control device 1 in Fig. 9 includes a processor 52 such as a CPU, a main storage device 53 such as a RAM, an auxiliary storage device 54 such as an HDD, a network interface 55 such as a LAN (Local Area Network) board, a device interface 56 such as a memory slot or a memory port, and a bus 57 that connects these devices to each other.
[0068] In this embodiment, a program for causing a computer to execute the information processing of the control device 1 is installed in the auxiliary storage device 54. The control device 1 expands this program in the main storage device 53 and executes it by the processor 52. As a result, the functions of each block shown in Fig. 3 are realized within the control device 1, and it becomes possible to write write information to the tag variables of the other control devices 1 described in this embodiment. Further, the control device 1 is connected to the Ethernet 20 via the network interface 55.
[0069] This program can be installed, for example, by attaching an external device 58 that records this program to the device interface 56 and storing this program from the external device 58 in the auxiliary storage device 54. Examples of the external device 58 are a computer-readable recording medium and a recording device incorporating such a recording medium. Examples of the recording medium are CD-ROM (Compact Disk Read Only Memory), CD-R (Compact Disk Recordable), flexible disk, DVD-ROM (Digital Versatile Disk Read Only Memory), DVD-R (Digital Versatile Disk Recordable), and an example of the recording device is an HDD. Also, this program can be installed, for example, by downloading this program via the network interface 55. As a result, it becomes possible to realize the control device 1 by software.
[0070] According to this embodiment, the control device 1 writes write information to the tag variables of other control devices 1 using a special instruction word (TS_REAL) as a user program. As a result, the user can write write information by specifying tag variables in other control devices 1 as well as in their own control device 1. Therefore, there is no need to be aware of the physical address, the construction burden of the user program is reduced, and the occurrence of bugs can be suppressed.
[0071] Also, according to this embodiment, when transmitting write information, the control device 1 does not require a scan transmission space, and data is transmitted only when write information is registered in the transmission information registration unit 13. Therefore, data communication can be minimized.
[0072] Also, according to this embodiment, the tool 3 has a tag information database in which the tag variables are linked to the physical addresses of the respective control devices 1. Further, the tool 3 links this information when creating a user program. As a result, the user does not need to add variables to the transmission area 16 and the reception area 17, the construction burden of the program can be reduced, and the management burden of the management materials can also be reduced.
[0073] Some embodiments have been described above, but these embodiments are presented only as examples and are not intended to limit the scope of the invention. The novel control device 1 described in this specification can be implemented in various other forms. Also, various omissions, substitutions, and changes can be made to the form of the control device 1 described in this specification without departing from the gist of the invention. The scope of the appended claims and equivalents thereof are intended to include such forms and modifications within the scope and gist of the invention.
Description of Reference Numerals
[0074] 1: Control device, 1a: Control device, 1b: Control device, 1a’: Control device, 1b’: Control device, 2: Monitoring device, 3: Tool, 4: Ethernet hub, 5: I / O device, 10: Distributed control system, 11: User program execution unit, 12: Tag variable storage unit, 13: Transmission information registration unit, 14: Reception information registration unit, 15: Synchronization processing unit, 16: Transmission area, 17: Reception area, 20: Ethernet, 30: I / O network, 52: Processor, 53: Main memory device, 54: Auxiliary storage device, 55: Network interface, 56: Device interface, 57: Bus, 58: External device
Claims
1. A user program execution unit that executes a user program for generating write information including a write destination physical address and a write value based on tag information indicating an element name of a tag variable structure specified by a user; A transmission information registration unit that accepts registration of the write information based on execution of the user program; A synchronization processing unit that transmits the write information accepted for registration by the transmission information registration unit at a predetermined first timing. A control device.
2. Further comprising a reception information registration unit that accepts registration of the received write information, The synchronization processing unit writes the write value included in the write information accepted for registration by the reception information registration unit to a corresponding physical address at a predetermined second timing. The control device according to claim 1.
3. The control device according to claim 1, wherein the user program is generated by associating the tag information with the physical address of the write destination by a tag information database.
4. The control device according to claim 1, wherein the transmission information registration unit accepts registration of the write information when a predetermined execution condition is satisfied and the write value changes during execution of the user program.