SCADA webpage HMI system

Abstract

The SCADA web page HMI client device is provided with a plurality of PLCs, a plurality of HMI client devices, and an SCADA device. A SCADA server device is provided with a communication driver and a client management unit connected to a plurality of HMI client devices. The client management unit transmits, to the communication driver, in-use screen information indicating a screen currently used in the HMI client device. A communication driver acquires, for each screen displayed in an HMI client device, a screen-specific device list in which a component, and a serial number and a memory address of a PLC in which signal data corresponding to the component is stored are defined. Signal data specified in the screen-specific device list corresponding to the currently used screen indicated by the in-use screen information is screened, a screen identifier is further added to the screened signal data, and the signal data is transmitted to the client management unit for each data type.

Description

Technical Field

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

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

[0003] SCADA has HMI (Human Machine Interface), PLC (Programmable Logic Controller) and communication base station as subsystems. HMI is a mechanism that displays the data of the monitored device to the operator so that the operator can monitor and control the monitored device. PLC receives (collects) the data of the monitored device or sends control instructions to the monitored device.

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

[0005] In large-scale systems, HMI subsystems sometimes connect hundreds of thousands of signals to PLCs. In conventional server devices that are responsible for both monitoring and control and data collection, high-performance processors and large-capacity memories are required to process a large number of signals in real time, which increases costs.

[0006] In order to realize the low cost of SCADA HMI subsystem, the inventor of the present application has developed a browser-based SCADA HMI subsystem. Thus, the HMI screen can be realized as a web application that operates on a web browser. As one of the advantages of realizing the HMI screen on a web browser, by switching the URL (including the port number), data can be easily obtained from different web servers.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2017-27211

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 11-120104 Summary of the invention

[0011] Problems that the invention will solve

[0012] However, in a large-scale SCADA webpage HMI system, it is envisaged that a large number (e.g., 128) of HMI client devices are connected to one SCADA server device. For example, in a steel hot rolling plant, a large number of sensors and actuators are configured on the rolling production line, and signal data including sensor detection signals and actuator control signals are sent to the PLC via a control network. The signals collected in the PLC must be sent to each HMI client device in real time. Therefore, it is required to integrate the functions of the communication driver and the client management unit in the SCADA server device, thereby managing a large number (e.g., 128) of HMI client devices through one SCADA server device. At the same time, for example, it is required that the display response is within 200msec and the operation response is within 500msec, so as to respond at a high speed. In order to achieve this requirement, it is necessary to realize the efficiency of signal processing in the SCADA server device.

[0013] The present disclosure is made to solve the above-mentioned problems. An object of the present disclosure is to provide a SCADA web HMI system that can realize efficient signal processing in a SCADA server device.

[0014] Means for solving problems

[0015] The first viewpoint relates to a SCADA web page HMI system. The SCADA web page HMI system comprises a plurality of programmable logic controllers (hereinafter referred to as "PLC"), a plurality of HMI (Human Machine Interface) client devices, and a SCADA (Supervisory Control And Data Acquisition) server device connected via a computer network. The PLC is configured to have a plurality of memory addresses for storing signal data related to a field device group constituting an industrial plant, and to send block data containing a collection of signal data to the computer network at a certain period. The HMI client device is configured to execute a web browser for displaying a plurality of HMI screens (hereinafter referred to as "screens") configured with a plurality of components respectively. The SCADA server device comprises a communication driver and a client management unit connected to a plurality of HMI client devices. The communication driver receives the block data sent from the PLC, divides the received block data into signal data of each data type, adds a signal identifier to the divided signal data, and sends it to the client management unit according to each data type. The client management unit receives the signal data sent from the communication driver, and sends the received signal data to the HMI client device corresponding to the signal identifier. The client management unit obtains in-use screen information indicating a screen currently in use in the HMI client device, and sends the obtained in-use screen information to the communication driver. The communication driver obtains a screen-specific device list that specifies a component and a number and a memory address of a PLC storing signal data corresponding to the component, respectively, for each screen displayed in the HMI client device, filters the signal data specified in the screen-specific device list corresponding to the screen currently in use indicated by the in-use screen information, and sends the filtered signal data to the client management unit according to each data type.

[0016] However, it is necessary to make a one-to-one correspondence between the components displayed on the screen and the signal data associated with the components. Therefore, there is a situation where the components displayed on the screen are referenced in other screens. Therefore, the second viewpoint has the following characteristics on the basis of the first viewpoint. The communication driver HMI obtains a screen reference device list of screens that respectively specify components and reference sources for reference components according to each screen displayed in the client device, and sends the signal data of the components specified in the screen reference device list corresponding to the currently used screen shown in the screen information in use to the client management unit according to each data type.

[0017] The third viewpoint has the following features based on the second viewpoint. The SCADA web HMI system also has: a screen design device connected to the computer network, having an engineering tool for designing screens. The screen design device designs screens and creates a screen inherent device list and a screen reference device list corresponding to the designed screens.

[0018] The fourth aspect is based on any one of the first to third aspects and has the following features: The communication driver acquires a screen common device list regardless of the type of screen displayed in the HMI client device, the screen common device list specifies the warning information displayed on the screen and the number of the PLC storing the signal data corresponding to the warning information and the memory address, and when the value of the signal data specified in the screen common device list is updated, the communication driver sends the updated signal data to the client management unit.

[0019] Effects of the Invention

[0020] According to the first viewpoint of the present disclosure, the communication driver filters the signal data related to the screen currently in use in a certain HMI client device, and only sends the filtered signal data from the communication driver to the client management unit. That is, the communication driver uses the screen information in use and the screen inherent device list to filter the signal data of the screen currently not in use in the HMI client device. As a result, the signal processing in the SCADA server device can be made more efficient, and as a result, the signal processing in the SCADA webpage HMI system can be made more efficient.

[0021] According to the second viewpoint, by using the screen reference device list, even when the screen of the reference source is not displayed in any HMI client device, only the signal data of the referenced component can be sent from the communication driver to the client management unit. In this case, among the signal data of the reference source screen, signal data other than the referenced component is not sent from the communication driver to the client management unit, so that the signal processing in the SCADA server device can be further improved in efficiency.

[0022] According to the third aspect, the communication driver can obtain the screen-specific device list and the screen reference device list created by the screen design device.

[0023] According to the fourth aspect, by using the screen common device list, warning information can be displayed regardless of the screen displayed on the HMI client device. Since the screen common device list does not need to be created for each screen, management becomes easier than when each is specified in the screen specific device list. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a diagram for explaining a configuration example of the SCADA web HMI system according to the first embodiment.

[0025] Figure 2 This is a schematic diagram for explaining the screen-specific device list corresponding to the HMI screen.

[0026] Figure 3 This is a schematic diagram for explaining the operation of the SCADA server device in the first embodiment.

[0027] Figure 4 This is a schematic diagram for explaining signal processing in a SCADA server device.

[0028] Figure 5 is a diagram for explaining the update mark.

[0029] Figure 6 This is a schematic diagram for explaining the screen common device list.

[0030] Figure 7 This is a schematic diagram for explaining the screen-specific device list corresponding to the HMI screen.

[0031] Figure 8 This is a schematic diagram for explaining the operation of the SCADA server device in the second embodiment.

[0032] Fig. 9 This is a block diagram showing a hardware configuration example of a SCADA server device and an HMI client device. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals are given to common elements in each figure, and repeated descriptions are omitted.

[0034] Implementation method 1.

[0035] Figure 1 This is a diagram for explaining a configuration example of the SCADA web HMI system 1 according to the first embodiment.

[0036] The SCADA web HMI system 1 includes a plurality of PLCs 2, a SCADA server device (hereinafter also referred to as a "server") 3, a plurality of HMI client devices (hereinafter also referred to as a "client") 4, and a screen design device 5. These PLCs 2, servers 3, clients 4, and screen design devices 5 are connected to each other via a computer network 61. The computer network 61 is, for example, Ethernet (registered trademark).

[0037] PLC2 is connected to the field equipment group constituting the industrial plant via the control network 62. The industrial plant is, for example, a steel rolling plant having a rolling line RL. In the rolling line RL, a plurality of sensors and actuators are configured as the field equipment group. The sensors and actuators are connected to PLC2 via the network 62. PLC2 has an address table inside, in which the memory addresses storing signal data related to the plurality of sensors and actuators (hereinafter also referred to as "PLC signals") are specified. PLC2 sends a data packet (PACKET) containing a set of a plurality of PLC signals, i.e., block data (BLOCK DATA), to the computer network 61 at a certain period by multicast or broadcast. The sending period is set, for example, in the range of a few msec to a few hundred msec. A block data contains tens to hundreds of PLC signals. PLC signals include, for example, input and output signals (including actuator control signals and sensor detection signals) and alarm signals. The block data contains at least one of a set of input and output signals and a set of alarm signals. Regardless of whether the value of the PLC signal has changed relative to the previous value, the block data is periodically sent to the server 3.

[0038] 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 Fig. 9 The processor 301 , the memory 302 , and the network interface 303 are shown. The processor 301 executes the program stored in the memory 302 , so that the processor 301 is configured to execute various processes and various functions of the server 3 .

[0039] The communication driver 31 performs reception processing of block data received from PLC2 at a certain period, and unpacking processing of decomposing the received block data into multiple PLC signals of each data type. As the data type of the PLC signal, "BIT (data size 1 bit)", "SHORT (data size 2 bytes)", and "FLOAT (data size 4 bytes)" can be exemplified, but other data types can be used. In addition, the communication driver 31 performs data packet processing (sending processing) of adding a signal identifier corresponding to each PLC signal to generate a data packet (PACKET) of each data type and sending the generated data packet to the client management unit 32. That is, the data sent from the communication driver 31 to the client management unit 32 is a pair of the signal identifier and the value of the PLC signal.

[0040] The signal identifier corresponds to the string written by the application designer and is a binary type ID unique to each data type. The data size of the signal identifier is, for example, 23 bits. Thus, the signal identifier can represent approximately 8 million PLC signals according to each data type, which is sufficient to correspond to a large-scale SCADA web HMI system 1. If it is BIT type data, the signal identifier is 23 bits, and the value of the PLC signal (data) is 1 bit, so the data size of each signal is 24 bits (= 3 bytes). If it is float type data, the signal identifier is 23 bits, and the value of the data is 4 bytes, so 1 bit of padding is added and the data size of each signal is 7 bytes.

[0041] The client management unit 32 receives the data packet (PLC signal of each data type) received from the communication driver 31, uses the signal identifier as an index to store the PLC signal according to each data type, classifies the stored PLC signal according to each HMI screen 41, and refers to the conversion table CT2 described later, attaches the screen identifier corresponding to the signal identifier to the PLC signal (data packet) and sends it to the client 4.

[0042] Client 4 has the following Fig. 9 The processor 401, memory 402, and monitor 403 are shown. The processor 401 executes the program stored in the memory 402, so that the processor 401 is configured to execute the web browser 40 that displays the HMI screen 41 configured with the display component (hereinafter referred to as "component") 42. The component 42 is also called "product". The monitor 403 displays the HMI screen 41 of the web browser 40.

[0043] The web browser 40 can acquire various information of 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 for which real-time performance is required.

[0044] When the HMI screen 41 currently used is a monitoring screen, the web browser 40 changes the display state of the component 42 according to the PLC signal sent from the server 3, that is, the PLC signal from the sensor and the actuator. The change of the display state is, for example, a change of a numerical value, a character, a color, or a shape. The component 42 is dynamically displayed according to the change of the PLC signal. Therefore, the component 42 is associated with the PLC signal.

[0045] However, generally, all PLC signals decomposed by the communication driver 31 are sent to the client management unit 32, but this may increase the processing load in the client management unit 32. Among the PLC signals sent to the client management unit 32, there are PLC signals of components 42 of the HMI screen 41 that are not used (displayed) by any client 4, and such PLC signals do not need to be sent to the client management unit 32.

[0046] Therefore, in this embodiment, the communication driver 31 is provided with a filtering function. Figure 2 to Figure 4 , the filtering function of the communication driver 31 is explained. Figure 2 This is a schematic diagram for explaining the screen-specific device list corresponding to the HMI screen. Figure 3 This is a schematic diagram for explaining the operation of the server 3 in the first embodiment. Figure 4 It is a schematic diagram for explaining signal processing in the server 3.

[0047] The communication driver 31 obtains the screen-specific device list DL2 for each HMI screen 41 displayed by the client 4. The screen-specific device list DL2 specifies a plurality of components, the number and memory address of the PLC 2 storing the PLC signal corresponding to each component, and the signal data type. The screen-specific device list DL2 can be downloaded from the screen design device 5. The screen design device 5 has an engineering tool 50. When the screen design device 5 designs each HMI screen 41 using the engineering tool 50, it creates the screen-specific device list DL2, which will be described later, and the PLC signal corresponding to each component. Figure 7 The screen common device list L1 shown in the figure, and the screen reference device list L3 described in the second embodiment described later. The communication driver 31 creates a conversion table CT1 between PLC addresses and signal identifiers based on the various device lists L1 to L3, and creates a conversion table CT2 between screen identifiers and signal identifiers. The created conversion table CT2 between screen identifiers and signal identifiers is transmitted to the client management unit 32 and shared. The screen identifier is a unique identifier that represents the displayed HMI screen 41.

[0048] Each PLC2 has an address book, and the PLC signals corresponding to the components are stored in the memory addresses specified in the address book. Figure 2The HMI screen (G001) 41 shown is configured with a plurality of components. Components VB1 to VB4 are bar graphs whose heights change according to the value of the PLC signal of PLC2A. The numerical values ​​of components NI1 to NI6 change according to the value of the PLC signal of PLC2B, and component METER1 is a meter whose needle position changes according to the value of the PLC signal of PLC2B. Components PL1 and PL2 are operation buttons that transmit instructions to the actuator via the PLC signal of PLC2C. Components PL1 and PL2 are operated by the operator on the HMI screen 41. Components SL1 to SL3 are animation components whose colors change according to the PLC signal of PLC2C. Components SL1 to SL3 are configured to change color when components PL1 and PL2 are in a specified state.

[0049] In the screen-specific device list DL2, for example, a component name "VB1", a PLC number "2A" storing a PLC signal corresponding to the component VB1, a memory address "400000" in PLC2A, and a data type "FLOAT" of the PLC signal are specified.

[0050] The client management unit 32 has a client connection management function 321. The client connection management function 321 generates the screen information US in use. The screen information US in use is information about the HMI screen 41 currently used (displayed) by a certain client 4. The generated screen information US in use is sent to the communication driver 31. Thus, the communication driver 31 can use the screen information US in use in the filtering function.

[0051] The communication driver 31 performs filtering of the PLC signal using the screen information US in use and the screen inherent device list DL2. That is, the communication driver 31 does not send the PLC signal specified in the screen inherent device list DL2 of the HMI screen 41 that is not currently in use (displayed) to the client management unit 32. On the other hand, the communication driver 31 adds an identifier to the PLC signal specified in the screen inherent device list DL2 of the HMI screen 41 that is currently in use (displayed) and sends it to the client management unit 32.

[0052] At this time, although all PLC signals specified in the screen-specific device list DL2 may be sent, it is preferred to send only the PLC signals whose values ​​are updated. Figure 5 As shown, the communication driver 31 can be configured to have an update bit that turns on when the value of the PLC signal is updated (turns off when it is not updated). Figure 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 a PLC signal whose update bit is ON among the PLC signals specified in the screen unique device list DL2 to the client management unit 32 .

[0053] In addition, regardless of the type of the displayed HMI screen 41, in order to notify the operator of a warning message indicating that the value of a specific PLC signal has changed, it is required to display a dialog box of the warning message on the HMI screen 41. In order to meet this requirement, the screen sharing device list DL1 is used. Figure 6 This is a schematic diagram for explaining the screen common device list DL1. Figure 6 The screen sharing device list shown

[0054] DL1 has the same format as the above screen-specific device list DL2.

[0055] In DL1, for example, a signal name "ARM1" is defined, and a corresponding

[0056] The PLC number "PLC2A" of the PLC signal, the memory address "400100" in PLC2A, and the data type "FLOAT" of the PLC signal. If the value of the PLC signal corresponding to the signal "ARM1" is updated, the communication driver 31 sends the PLC signal with the updated value to the client management unit 32. As a result, a dialog box of a warning message can be displayed on the HMI screen 41 regardless of the displayed HMI screen 41 to report to the operator. In addition, whether the value is updated can be distinguished by the above-mentioned update bit.

[0057] As described above, according to the present embodiment, not all PLC signals received by the communication driver 31 are sent to the client management unit 32, but only the PLC signals of the HMI screen 41 currently used in a certain client 4 are screened, and only the screened PLC signals are sent from the communication driver 31 to the client management unit 32. That is, the communication driver 31 uses the screen information in use and the screen-specific device list DL2 to filter the PLC signals of the HMI screen 41 that is not displayed in the client 4. As a result, the signal processing in the server 3 can be made more efficient, and as a result, the signal processing in the SCADA web HMI system 1 can be made more efficient.

[0058] Implementation method 2.

[0059] Next, the second embodiment of the present disclosure will be described. In this embodiment, the description will be centered on the differences from the first embodiment. As described in the first embodiment, it is necessary to make the components 42 displayed on the HMI screen 41 correspond to the PLC signals of the components 42 on a one-to-one basis. Therefore, for example, there is a case where a component configured on the HMI screen (G001) 41 is referenced in another HMI screen (G002) 41.

[0060] Figure 7It is a schematic diagram for explaining the screen reference device list DL3 corresponding to the HMI screen 41 . Figure 8 This is a schematic diagram for explaining the operation of the server 3 in the second embodiment.

[0061] Figure 7 The two components "PL1, PL2" arranged on the HMI screen (G001) 41 shown refer to the components "PL1, PL2" of another HMI screen (G002). In this case, the components "PL1, PL2" are not specified in the screen-specific device list DL2 of the HMI screen (G001), but in the screen-specific device list DL2 of the HMI screen (G002) that is omitted from the illustration. These components "PL1, PL2" are specified in the screen reference device list DL3 of the HMI screen (G001). In the screen reference device list DL3, for example, the component name "PL1" and the screen name "G002" of the reference source are specified.

[0062] The communication driver 31 performs filtering of the PLC signal using the screen information US in use, the screen inherent device list DL2, and the screen reference device list DL3. As in the above-mentioned embodiment 1, the communication driver 31 does not send the PLC signal specified in the screen inherent device list DL2 of the HMI screen 41 that is not currently in use (displayed) to the client management unit 32. On the other hand, the communication driver 31 sends the PLC signal specified in the screen inherent device list DL2 of the HMI screen 41 that is currently in use (displayed) to the client management unit 32. Moreover, in the present embodiment, the communication driver 31 sends the PLC signal of the reference source specified in the screen reference device list DL3 of the HMI screen 41 to the client management unit 32. At this time, as in the above-mentioned embodiment 1, all the PLC signals specified in the screen inherent device list DL2 and the screen reference device list DL3 may also be sent, but it is preferred to send only the PLC signal whose value is updated.

[0063] As described above, according to the present embodiment, not all PLC signals received by the communication driver 31 are sent to the client management unit 32, but the PLC signals of the HMI screen 41 displayed in a certain client 4 and the PLC signals of the components 42 referenced by the HMI screen 41 in use are filtered, and only the filtered PLC signals are sent from the communication driver 31 to the client management unit 32. That is, the communication driver 31 uses the screen information in use, the screen inherent device list DL2 and the screen reference device list DL3 to filter the PLC signals of the HMI screen 41 not displayed in the client 4. As a result, the efficiency of signal processing in the server 3 can be achieved, and as a result, the efficiency of signal processing in the SCADA web HMI system 1 can be achieved. In addition, since the PLC signals other than the referenced components 42 among the PLC signals of the HMI screen 41 of the reference source are not sent from the communication driver to the client management unit, the efficiency of signal processing in the SCADA server device can be further achieved.

[0064] Fig. 9 3 is a block diagram showing an example of the hardware configuration of the server 3 and the client 4. Each of the above-mentioned processes of the server 3 is implemented by a processing circuit. The processing circuit is formed by connecting a processor 301, a memory 302, and a network interface 303. The processor 301 executes various programs stored in the memory 302, thereby realizing various filtering functions of the server 3. The memory 302 includes a main storage device and an auxiliary storage device. In addition, the memory 302 includes a storage area that can temporarily store PLC signals.

[0065] Each of the above-mentioned processes of the client 4 is implemented by a processing circuit. The processing circuit is composed of a processor 401, a memory 402, at least one monitor 403, a network interface 404, and an input interface 405. The processor 401 implements 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 also be provided. The input interface 405 is an input device such as a keyboard, a mouse, a touch panel, etc. The operator can use the input interface 405, for example, to operate Figure 2 Components "PL1, PL2" of the HMI screen (G001) 41 are shown.

[0066] The above describes the embodiment of the present invention, but the present invention is not limited to the above embodiment and can be implemented in various modifications without departing from the scope of the present invention. In the above embodiment, the various device lists DL1 to DL3 are obtained from the screen design device 5, but they can also be obtained from an external device.

[0067] In addition, when the numbers of the number, quantity, amount, range, etc. of each element are mentioned in the above-mentioned embodiments, the present invention is not limited to the mentioned numbers except for the cases where it is particularly clearly stated or the cases where it is clearly determined to be the numbers in principle. In addition, the structures and the like described in the above-mentioned embodiments are not necessarily essential to the present invention except for the cases where it is particularly clearly stated or the cases where it is clearly determined to be the numbers in principle.

[0068] Description of Reference Numerals

[0069] 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~VB4, NI1~NI6, METER1, PL1, PL2, SL1~SL3…Components, display components, DL1…Screen common device list, DL2…Screen unique device list, DL3…Screen reference device list.

Claims

1. A SCADA web HMI system, comprising 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 connected via a computer network, wherein: The PLC is configured to have a plurality of memory addresses for storing signal data related to a group of field devices constituting an industrial plant, and to send block data including a collection of the signal data to the computer network at a certain period. The HMI client device is configured to execute a web browser for displaying a plurality of screens on which a plurality of components are arranged, respectively. 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 sent from the PLC, divide the block data into signal data of each data type, add a signal identifier to the divided signal data, and send it to the client management unit according to 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 obtain in-use screen information indicating the screen currently in use in the HMI client device and transmit the obtained screen information to the communication driver. The communication driver is configured as follows: According to each of the screens displayed in the HMI client device, a screen-specific device list is obtained, wherein the screen-specific device list specifies the components, and the numbers of the PLCs storing the signal data corresponding to the components and the memory addresses, respectively. The signal data specified in the screen-specific device list corresponding to the screen currently in use indicated by the screen information in use is filtered, a screen identifier is further added to the filtered signal data, and the data is sent to the client management unit according to each data type.

2. The SCADA web page HMI system as claimed in claim 1, wherein: The communication driver is configured as follows: According to each of the screens displayed in the HMI client device, a screen reference device list is obtained, wherein the screen reference device list specifies the components and the screens that are reference sources for referring to the components, respectively; The screen identifier is further added to the signal data of the component specified in the screen reference device list corresponding to the screen currently in use indicated by the screen information in use, and the signal data is transmitted to the client management unit for each data type.

3. The SCADA web page HMI system as claimed in claim 2, wherein: Also available: A screen design device, connected to the computer network, 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 reference device list corresponding to the designed screen.

4. The SCADA webpage HMI system according to any one of claims 1 to 3, wherein: The communication driver is configured as follows: irrespective of the type of the screen displayed in the HMI client device, a screen common device list is obtained, wherein the screen common device list specifies the warning information displayed on the screen and the number of the PLC storing the signal data corresponding to the warning information and the memory address, When the value of the signal data specified in the screen common device list is updated, the updated signal data is transmitted to the client management unit.

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