SCADA Web HMI System

Abstract

In the present invention, a SCADA web HMI client apparatus comprises a plurality of PLCs, a plurality of HMI client devices, and a SCADA device. A SCADA server device comprises a communication driver and a client management unit connected to the plurality of HMI client devices. The client management unit transmits, to the communication driver, in-use screen information indicating a screen currently used by an HMI client device. For each screen displayed by the HMI client device, the communication driver: acquires a screen-specific device list in which parts and PLC numbers and memory addresses for storing signal data corresponding to the parts are respectively determined; selects signal data determined in the screen-specific device list corresponding to the currently used screen indicated by the in-use screen information; further adds a screen identifier to the selected signal data; and transmits the resulting data to the client management unit for each data type.

Description

[Technical Field]

[0001] The present invention relates to a SCADA web HMI system, and more particularly to a technique for improving the efficiency of signal processing in a large-scale SCADA web HMI system. [Background technology]

[0002] SCADA (Supervisory Control And Data Acquisition) is known as a system for monitoring and controlling social infrastructure systems. Examples of social infrastructure systems include steel rolling systems, power transmission and transformation systems, water and sewerage treatment systems, building management systems, and road systems. SCADA is a type of industrial control system that uses computers to monitor systems, control processes, and collect data. SCADA requires responsiveness (real-time performance) that matches the system's processing performance.

[0003] SCADA has subsystems such as HMI (Human Machine Interface), PLC (Programmable Logic Controller), and communication infrastructure. HMI is a mechanism that presents data from monitored devices to operators, allowing them to monitor and control the monitored devices. PLC receives (collects) data from monitored devices and sends control commands to the monitored devices.

[0004] As an example of a SCADA HMI subsystem, Patent Document 1 discloses a system including an HMI client device and a server device. In a conventional SCADA such as that disclosed in Patent Document 1, the server device transmits data received from a PLC (PLC signals such as input / output signals and alarm signals) to the HMI client device. The input / output signals are signals related to the monitored devices (field devices that make up an industrial plant), and include, for example, actuator control signals and sensor detection signals.

[0005] In large-scale systems, the HMI subsystem may connect hundreds of thousands of signals to the PLC. Conventional server devices that handle both supervisory control and data collection require high-performance processors and large-capacity memory to process a large number of signals in real time, which increases costs.

[0006] To reduce the cost of SCADA HMI subsystems, the inventors of this application have developed a browser-based SCADA HMI subsystem. This allows the HMI screen to be implemented as a web application that runs on a web browser. One of the advantages of implementing an HMI screen on a web browser is that data can be easily obtained from different web servers by switching URLs (including port numbers). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2017-27211 [Patent Document 2] Japanese Patent Application Publication No. 11-120104 Summary of the Invention [Problem to be solved by the invention]

[0008] In a large-scale SCADA web HMI system, it is expected that a large number of HMI client devices (e.g., 128 devices) will be connected to a single SCADA server. For example, in a steel hot rolling plant, a large number of sensors and actuators are installed on the rolling line, and signal data, including sensor detection signals and actuator control signals, is transmitted to a PLC via a control network. The signals collected by the PLC must be transmitted to each HMI client device in real time. Therefore, by consolidating the functions of a communication driver and a client management unit in the SCADA server, a single SCADA server is required to manage a large number of HMI client devices (e.g., 128 devices). At the same time, high-speed response is required, such as a display response time of 200 msec or less and an operation response time of 500 msec or less. To meet these requirements, it is necessary to improve the efficiency of signal processing in the SCADA server.

[0009] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a SCADA web HMI system that can improve the efficiency of signal processing in a SCADA server device. [Means for solving the problem]

[0010] The first aspect relates to a SCADA web HMI system. The SCADA web HMI system includes multiple programmable logic controllers (hereinafter referred to as "PLCs"), multiple HMI (Human Machine Interface) client devices, and a SCADA (Supervisory Control and Data Acquisition) server device, all connected via a computer network. The PLC has multiple memory addresses for storing signal data related to a group of field devices constituting an industrial plant, and periodically transmits block data including a collection of signal data to the computer network. The HMI client devices execute a web browser that displays multiple HMI screens (hereinafter referred to as "screens") on which multiple parts are arranged. The SCADA server device includes a communication driver and a client management unit connected to the multiple HMI client devices. The communication driver receives block data transmitted from the PLC, divides the received block data into signal data for each data type, adds signal identifiers to the divided signal data, and transmits the data to the client management unit for each data type. The client management unit receives the signal data transmitted from the communication driver and transmits the received signal data to the HMI client device corresponding to the signal identifier. The client management unit acquires in-use screen information indicating the screen currently in use on the HMI client device and transmits the acquired in-use screen information to the communication driver. The communication driver acquires a screen-specific device list that defines, for each screen displayed on the HMI client device, parts and the PLC numbers and memory addresses where the signal data corresponding to the parts are stored, selects signal data defined in the screen-specific device list that corresponds to the currently-used screen indicated by the in-use screen information, and transmits the selected signal data by data type to the client management unit.

[0011] However, there needs to be a one-to-one correspondence between parts displayed on a screen and the signal data associated with that part. For this reason, a part displayed on a screen may be referenced on another screen. Therefore, the second aspect has the following additional feature in addition to the first aspect: The communications driver acquires a screen reference device list that defines parts and the screens that referenced the parts for each screen displayed on the HMI client device, and transmits the signal data of the parts defined in the screen reference device list that corresponds to the currently used screen indicated by the currently used screen information to the client management unit for each data type.

[0012] The third aspect has the same features as the second aspect, but further includes the following: the SCADA web HMI system further includes a screen design device connected to the computer network and having an engineering tool for designing a screen. The screen design device designs the screen and creates a screen-specific device list and a screen-reference device list corresponding to the designed screen.

[0013] A fourth aspect of the present invention has the following characteristics in addition to any one of the first to third aspects: 、H Regardless of the type of screen displayed on the MI client device, a screen common device list is obtained that defines the warning information to be displayed on the screen, the PLC number where signal data corresponding to the warning information is stored, and the memory address, and when the value of the signal data defined in the screen common device list is updated, the updated signal data is sent to the client management unit. [Effects of the Invention]

[0014] According to a first aspect of the present disclosure, a communication driver selects signal data related to a screen currently in use on any HMI client device, and transmits only the selected signal data to a client management unit. That is, the communication driver uses the in-use screen information and the screen-specific device list to filter signal data related to a screen not currently in use on an HMI client device. This improves the efficiency of signal processing in the SCADA server device, and as a result, improves the efficiency of signal processing in the SCADA web HMI system.

[0015] According to the second aspect, by using the screen reference device list, even when none of the HMI client devices is displaying the referenced screen, it is possible to transmit only the signal data of the referenced parts from the communication driver to the client management unit. In this case, signal data of the referenced screen other than the referenced parts is not transmitted from the communication driver to the client management unit, thereby further improving the efficiency of signal processing in the SCADA server device.

[0016] According to the third aspect, the communication driver can acquire the screen-specific device list and the screen-reference device list created by the screen design device.

[0017] According to the fourth aspect, by using a screen-common device list, it is possible to display warning information regardless of what screen is displayed on the HMI client device. Since a screen-common device list does not need to be created for each screen, management is easier than when a screen-specific device list is defined for each screen. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram for explaining a configuration example of a SCADA web HMI system according to a first embodiment. [Figure 2] FIG. 10 is a schematic diagram for explaining a screen-specific device list corresponding to an HMI screen. [Figure 3]FIG. 2 is a schematic diagram for explaining the operation of the SCADA server device in the first embodiment. [Figure 4] FIG. 2 is a schematic diagram for explaining signal processing in a SCADA server device. [Figure 5] FIG. 10 is a schematic diagram for explaining an update flag. [Figure 6] FIG. 10 is a schematic diagram for explaining a screen common device list. [Figure 7] FIG. 10 is a schematic diagram for explaining a screen-specific device list corresponding to an HMI screen. [Figure 8] FIG. 10 is a schematic diagram for explaining the operation of the SCADA server device in the second embodiment. [Figure 9] 2 is a block diagram showing an example of the hardware configuration of a SCADA server device and an HMI client device. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Elements common to the various drawings will be designated by the same reference numerals, and redundant description will be omitted.

[0020] Embodiment 1 FIG. 1 is a diagram illustrating an example of the configuration of a SCADA web HMI system 1 according to the first embodiment.

[0021] The SCADA web HMI system 1 comprises multiple PLCs 2, a SCADA server device (hereinafter also referred to as "server") 3, multiple HMI client devices (hereinafter also referred to as "clients") 4, and a screen design device 5. The PLCs 2, server 3, clients 4, and screen design device 5 are interconnected via a computer network 61. The computer network 61 is, for example, Ethernet (registered trademark).

[0022] The PLC 2 is connected to a group of field devices constituting an industrial plant via a control network 62. The industrial plant is, for example, a steel rolling plant having a rolling line RL. The rolling line RL is equipped with a group of field devices, including multiple sensors and actuators. The sensors and actuators are connected to the PLC 2 via the network 62. The PLC 2 has an internal address table that defines memory addresses for storing signal data (hereinafter also referred to as "PLC signals") related to the multiple sensors and actuators. The PLC 2 periodically transmits packets containing block data, which is a collection of multiple PLC signals, to the computer network 61 via multicast or broadcast. The transmission period is set, for example, within a range from several msec to several hundred msec. One block data contains tens to several hundred PLC signals. The PLC signals include, for example, input / output signals (including actuator control signals and sensor detection signals) and alarm signals. The block data includes at least one of a collection of input / output signals and a collection of alarm signals. The block data is periodically transmitted to the server 3 regardless of whether the value of the PLC signal has changed from the previous value.

[0023] The server 3 includes a communication driver 31 and a client management unit 32 connected to a plurality of clients 4. The server 3 includes a processor 301, a memory 302, and a network interface 303, which are shown in FIG. 9 and will be described later. The processor 301 is configured to execute various processes and functions of the server 3 by executing programs stored in the memory 302.

[0024] The communication driver 31 performs a reception process to receive block data from the PLC 2 at regular intervals and an unpacking process to break down the received block data into multiple PLC signals of each data type. Examples of data types for PLC signals include "BIT (data size 1 bit)," "SHORT (data size 2 bytes)," and "FLOAT (data size 4 bytes)," but other data types can also be used. Furthermore, the communication driver 31 performs packet processing (transmission processing) to generate packets for each data type by adding a signal identifier corresponding to each PLC signal, and transmit the generated packets to the client management unit 32. In other words, the data transmitted from the communication driver 31 to the client management unit 32 is a pair of a signal identifier and a PLC signal value.

[0025] The signal identifier corresponds to a character string written by the application designer and is a unique binary ID for each data type. The data size of the signal identifier is, for example, 23 bits. This allows the signal identifier to represent approximately 8 million PLC signals for each data type, making it fully compatible with large-scale SCADA web HMI systems 1. For BIT-type data, the signal identifier is 23 bits and the PLC signal (data) value is 1 bit, so the data size per signal is 24 bits (= 3 bytes). For float-type data, the signal identifier is 23 bits and the data value is 4 bytes, so with 1 bit of padding added, the data size per signal is 7 bytes.

[0026] The client management unit 32 receives packets (PLC signals for each data type) from the communication driver 31, uses the signal identifier as an index to store the PLC signals for each data type, sorts the stored PLC signals for each HMI screen 41, and refers to the conversion table CT2 described later to add a screen identifier corresponding to the signal identifier to the PLC signal (packet) and transmits it to the client 4.

[0027] The client 4 includes a processor 401, a memory 402, and a monitor 403, which are shown in FIG. 9 and will be described later. The processor 401 is configured to execute a program stored in the memory 402, thereby executing a web browser 40 that displays an HMI screen 41 on which display parts (hereinafter referred to as "parts") 42 are arranged. The parts 42 are also referred to as "products." The monitor 403 displays the HMI screen 41 of the web browser 40.

[0028] The web browser 40 can obtain various information in HTML documents related to the HMI screen 41 from a web server (not shown) specified by a URL. The web server is built in the server 3. The HMI screen 41 includes a monitoring screen that requires real-time performance.

[0029] When the currently used HMI screen 41 is a monitoring screen, the web browser 40 changes the display state of the part 42 in response to the PLC signal sent from the server 3, i.e., the PLC signal from the sensor or actuator. The change in the display state is, for example, a change in numerical value, character, color, or shape. The part 42 is dynamically displayed in response to the change in the PLC signal. For this reason, the part 42 and the PLC signal are linked.

[0030] Incidentally, it is common to send all of the PLC signals resolved by the communication driver 31 to the client management unit 32, but this may increase the processing load on the client management unit 32. The PLC signals sent to the client management unit 32 include PLC signals for parts 42 of an HMI screen 41 that are not being used (displayed) by any of the clients 4, and such PLC signals do not need to be sent to the client management unit 32.

[0031] Therefore, in this embodiment, the communication driver 31 is provided with a filtering function. The filtering function of the communication driver 31 will be described with reference to Figs. 2 to 4. Fig. 2 is a schematic diagram for explaining a screen-specific device list corresponding to an HMI screen. Fig. 3 is a schematic diagram for explaining the operation of the server 3 in the first embodiment. Fig. 4 is a schematic diagram for explaining signal processing in the server 3.

[0032] The communication driver 31 acquires a screen-specific device list DL2 that defines, for each HMI screen 41 displayed on the client 4, a plurality of parts, the numbers and memory addresses of the PLC 2 where the PLC signals corresponding to each part are stored, and the signal data types. The screen-specific device list DL2 can be acquired by downloading from the screen design device 5. The screen design device 5 has an engineering tool 50. When designing each HMI screen 41 using the engineering tool 50, the screen design device 5 downloads the screen-specific device list DL2 and the device list DL2 described in the drawings (described later). 6 Screen shown in Common Device List D L1 and a screen reference device list described in the second embodiment below. D L3 and the communication driver 31 creates various device lists. D L1~ D From L3, a conversion table CT1 between PLC addresses and signal identifiers is created, as well as a conversion table CT2 between screen identifiers and signal identifiers. The created conversion table CT2 between screen identifiers and signal identifiers is transferred to and shared by the client management unit 32. The screen identifier is a unique identifier that indicates the HMI screen 41 to be displayed.

[0033] Each PLC2 has its own address book, and the PLC signals corresponding to the parts are stored in memory addresses defined in the address book. Multiple parts are arranged on the HMI screen (G001) 41 shown in FIG. 2. Parts VB1 to VB4 are bar graphs whose height changes according to the value of the PLC signal from PLC2A. Parts NI1 to NI6 change their numerical values ​​according to the value of the PLC signal from PLC2B, and part METER1 is a meter whose needle position changes according to the value of the PLC signal from PLC2B. Parts PL1 and PL2 are operation buttons that transmit instructions to the actuator via the PLC signal from PLC2C. Parts PL1 and PL2 are operated by an operator on the HMI screen 41. Parts SL1 to SL3 are animation parts whose color changes according to the PLC signal from PLC2C. Parts SL1 to SL3 are configured to change color when parts PL1 and PL2 are in a predetermined state.

[0034] In the screen-specific device list DL2, for example, the part name "VB1", the PLC number "2A" and memory address "400000" within PLC2A where the PLC signal corresponding to part VB1 is stored, and the data type of the PLC signal "FLOAT" are defined.

[0035] The client management unit 32 has a client connection management function 321. The client connection management function 321 generates in-use screen information US. The in-use screen information US is information on an HMI screen 41 that is currently being used (displayed) by any of the clients 4. The generated in-use screen information US is sent to the communication driver 31. This allows the communication driver 31 to use the in-use screen information US for the filtering function.

[0036] The communication driver 31 filters PLC signals using the in-use screen information US and the screen-specific device list DL2. That is, the communication driver 31 does not send PLC signals defined in the screen-specific device list DL2 of an HMI screen 41 that is not currently being used (displayed) to the client management unit 32. On the other hand, the communication driver 31 adds an identifier to the PLC signals defined in the screen-specific device list DL2 of the HMI screen 41 that is currently being used (displayed) and sends them to the client management unit 32.

[0037] At this time, all PLC signals defined in the screen-specific device list DL2 may be transmitted, but it is preferable to transmit only PLC signals whose values ​​have been updated. In this case, as shown in FIG. 5, the communication driver 31 can be configured to have an update bit that is turned ON when the value of a PLC signal is updated (and OFF when the value is not updated). FIG. 5 is a schematic diagram for explaining the update flag. The update bit is a 1-bit update flag. The communication driver 31 can transmit to the client management unit 32, among the PLC signals defined in the screen-specific device list DL2, those PLC signals whose update bit is ON.

[0038] In addition, regardless of the type of HMI screen 41 being displayed, it is required to display a dialog box of warning information on the HMI screen 41 in order to notify the operator of warning information indicating that the value of a specific PLC signal has changed. General The device list DL1 is used. Fig. 6 is a schematic diagram for explaining the screen-shared device list DL1. General The device list DL1 has the same format as the screen-specific device list DL2. GeneralIn the device list DL1, for example, the signal name "ARM1," the PLC number "PLC2A" where the PLC signal corresponding to the signal "ARM1" is stored, the memory address "400100" within PLC2A, and the data type of the PLC signal "FLOAT" are defined. When the value of the PLC signal corresponding to the signal "ARM1" is updated, the communication driver 31 transmits the PLC signal with the updated value to the client management unit 32. This allows a warning information dialog box to be displayed on the HMI screen 41, regardless of the HMI screen 41 being displayed, to notify the operator. Whether the value has been updated can be determined by the update bit.

[0039] As described above, according to this embodiment, instead of transmitting all PLC signals received by the communication driver 31 to the client management unit 32, only the PLC signals of the HMI screen 41 currently being used by any of the clients 4 are selected, and only the selected PLC signals are transmitted from the communication driver 31 to the client management unit 32. In other words, the communication driver 31 uses the currently used screen information and the screen-specific device list DL2 to filter the PLC signals of the HMI screen 41 that is not being displayed by the client 4. This makes it possible to improve the efficiency of signal processing in the server 3, and as a result, makes it possible to improve the efficiency of signal processing in the SCADA web HMI system 1.

[0040] Embodiment 2 Next, a second embodiment of the present disclosure will be described. In this embodiment, differences from the first embodiment will be mainly described. As described in the first embodiment, it is necessary to have a one-to-one correspondence between the parts 42 displayed on the HMI screen 41 and the PLC signals of the parts 42. For this reason, for example, a part placed on an HMI screen (G001) 41 may be referenced on another HMI screen (G002) 41.

[0041] Fig. 7 is a schematic diagram for explaining the screen reference device list DL3 corresponding to the HMI screen 41. Fig. 8 is a schematic diagram for explaining the operation of the server 3 in the second embodiment.

[0042] Two parts "PL1, PL2" arranged on an HMI screen (G001) 41 shown in FIG. 7 refer to parts "PL1, PL2" on another HMI screen (G002). In this case, the parts "PL1, PL2" are defined in the screen-specific device list DL2 of the HMI screen (G002), not shown, but in the screen-specific device list DL2 of the HMI screen (G002), not shown. These parts "PL1, PL2" are defined in the screen-referenced device list DL3 of the HMI screen (G001). In the screen-referenced device list DL3, for example, the part name "PL1" and the referencing screen name "G002" are defined.

[0043] The communication driver 31 filters PLC signals using the in-use screen information US, the screen-specific device list DL2, and the screen-reference device list DL3. As in the first embodiment, the communication driver 31 does not transmit to the client manager 32 PLC signals defined in the screen-specific device list DL2 of an HMI screen 41 that is not currently being used (displayed). On the other hand, the communication driver 31 transmits to the client manager 32 PLC signals defined in the screen-specific device list DL2 of an HMI screen 41 that is currently being used (displayed). Furthermore, in this embodiment, the communication driver 31 transmits to the client manager 32 PLC signals of the reference source defined in the screen-reference device list DL3 of the HMI screen 41. At this time, as in the first embodiment, all PLC signals defined in the screen-specific device list DL2 and the screen-reference device list DL3 may be transmitted, but it is preferable to transmit only PLC signals whose values ​​have been updated.

[0044] As described above, according to this embodiment, instead of transmitting all PLC signals received by the communication driver 31 to the client management unit 32, the communication driver 31 selects between the PLC signals of the HMI screen 41 currently displayed on any of the clients 4 and the PLC signals of the parts 42 referenced on the HMI screen 41 currently in use, and transmits only the selected PLC signals from the communication driver 31 to the client management unit 32. That is, the communication driver 31 filters the PLC signals of the HMI screen 41 not displayed on the client 4 using the currently used screen information, the screen-specific device list DL2, and the screen-referenced device list DL3. This improves the efficiency of signal processing in the server 3, and as a result, improves the efficiency of signal processing in the SCADA web HMI system 1. Furthermore, because the communication driver does not transmit PLC signals of the PLC signals of the referencing HMI screen 41 other than the referenced parts 42 to the client management unit, the efficiency of signal processing in the SCADA server device can be further improved.

[0045] 9 is a block diagram showing an example of the hardware configuration of the server 3 and the client 4. Each process of the server 3 described above is realized by a processing circuit. The processing circuit is configured by connecting a processor 301, a memory 302, and a network interface 303. The processor 301 realizes each filtering function of the server 3 by executing various programs stored in the memory 302. The memory 302 includes a main storage device and an auxiliary storage device. The memory 302 also includes a storage area in which PLC signals can be temporarily stored.

[0046] Each process of the client 4 described above is realized by a processing circuit. The processing circuit is configured by connecting a processor 401, a memory 402, at least one monitor 403, a network interface 404, and an input interface 405. The processor 401 realizes each function of the client 4 by executing various programs stored in the memory 402. The memory 402 includes a main storage device and an auxiliary storage device. Multiple monitors 403 may be provided. The input interface 405 is an input device such as a keyboard, a mouse, or a touch panel. An operator can use the input interface 405 to operate, for example, parts "PL1, PL2" on the HMI screen (G001) 41 shown in FIG. 2.

[0047] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be implemented in various modifications without departing from the spirit of the present invention. In the above embodiments, the various device lists DL1 to DL3 are acquired from the screen design device 5, but they may also be acquired from an external device.

[0048] Furthermore, when the number, quantity, amount, range, etc. of each element is mentioned in the above-mentioned embodiments, the present invention is not limited to the mentioned numbers unless otherwise specified or clearly specified in principle. Furthermore, the structures, etc. described in the above-mentioned embodiments are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle. [Explanation of symbols]

[0049] 1...SCADA web HMI system, 2...Programmable logic controller (PLC), 3...SCADA server device, server, 31...Communication driver, 32...Client management unit, 4...HMI client device, client, 40...Web browser, 41...HMI screen (screen), 42, VB1 to VB4, NI1 to NI6, METER1, PL1, PL2, SL1 to SL3...Parts, display parts, DL1...Screen common device list, DL2...Screen specific device list, DL3...Screen reference device list

Claims

1. A SCADA web HMI system including a plurality of programmable logic controllers (hereinafter referred to as "PLCs"), a plurality of HMI (Human Machine Interface) client devices, and a SCADA (Supervisory Control And Data Acquisition) server device, which are connected via a computer network, the PLC has a plurality of memory addresses for storing signal data related to a group of field devices that constitute an industrial plant, and is configured to transmit block data including a set of the signal data to the computer network at regular intervals; the HMI client device is configured to execute a web browser that displays a plurality of screens, each of which has a plurality of parts arranged thereon; the SCADA server device includes a communication driver and a client management unit connected to the plurality of HMI client devices; the communication driver is configured to receive block data transmitted from the PLC, divide the block data into signal data for each data type, add a signal identifier to the divided signal data, and transmit the signal data to the client management unit for each data type; The client management unit is configured to receive the signal data transmitted from the communication driver and transmit the received signal data to the HMI client device corresponding to the signal identifier, the client management unit is configured to acquire in-use screen information indicating the screen currently being used on the HMI client device, and to transmit the acquired screen information to the communication driver; The communication driver obtain a screen-specific device list for each of the screens displayed on the HMI client device, in which the parts, the numbers of the PLCs in which the signal data corresponding to the parts are stored, and the memory addresses thereof are respectively defined; A SCADA web HMI system configured to select the signal data defined in the screen-specific device list corresponding to the currently used screen indicated by the in-use screen information, further add a screen identifier to the selected signal data, and transmit the data to the client management unit for each data type.

2. The communication driver obtain a screen reference device list in which the parts and the reference source screens that reference the parts are respectively defined for each of the screens displayed on the HMI client device; 2. The SCADA web HMI system according to claim 1, wherein the signal data of the part defined in the screen reference device list corresponding to the currently used screen indicated by the currently used screen information is further added with the screen identifier and transmitted to the client management unit for each data type.

3. 3. The SCADA web HMI system of claim 2, The system further comprises a screen design device connected to the computer network and having an engineering tool for designing the screen, The screen design device is configured to design the screen and create the screen-specific device list and the screen-referenced device list corresponding to the designed screen.

4. The communication driver acquire a screen common device list that defines warning information to be displayed on the screen, and the number and memory address of the PLC in which the signal data corresponding to the warning information is stored, regardless of the type of the screen displayed on the HMI client device; 4. The SCADA web HMI system according to claim 1, wherein when a value of the signal data defined in the screen common device list is updated, the SCADA web HMI system is configured to send the updated signal data to the client management unit.

Images