KR20020025442A - An Internet-based 3-dimensional remote monitor/control system - Google Patents

Abstract

PURPOSE: An internet-based 3-dimensional remote monitor/control system is provided to embody a 3-dimensional remote monitoring system based on a server/client structure on the Internet using a VRML(Virtual Reality Modeling Language). CONSTITUTION: A plurality of PLCs(Programmable Logic Controllers)(110) control processes. A plurality of multimeters install RS232 interfaces for measuring process parameters. A server system(100) connects a plurality of PLCs(110) and multimeters and connects to the Internet. A plurality of clients monitors an operation state of a process through data read from the server system(100) and connects to the server system(100) through the Internet for controlling the process through the PLCs(110).

Description

An Internet-based 3-dimensional remote monitor / control system

The present invention relates to an internet based three dimensional remote monitor / control system.

Today, various types of programmable logic controllers (PLCs) have been introduced and used for effective control of small and medium-sized production processes. This means that the PLC can be used effectively for closed loop control such as PI (D) as well as for sequence control occurring in the process and that the control algorithm can be simply changed using programming tools such as ladder diagrams. And so on. However, as society becomes more complex and diversified, process managers' behaviors and management areas are gradually expanding, and various methods for effectively solving these situations are being sought. In this research, active researches are being conducted on remote monitoring systems that enable the real-time monitoring of process operations at non-production sites and warning systems that promptly notify process managers of dangerous situations during process operation. It is becoming. Recently, Internet technology, which is rapidly developing, has been increasing in scope for research and application because users can easily obtain and distribute desired data beyond space constraints. In particular, the Java application running on the Internet is a very suitable language for implementing a system for remotely monitoring and controlling home appliances. Many applications using the same have been developed one after another.

PLCs, which are currently used for most process control, have a built-in RS232 interface for data transfer to and from external computers. However, no efficient process control technology has yet been established to transfer operational data inside the PLC to the host PC via the RS232 interface and remotely monitor these data over the Internet.

Most of the instruments used in the industry today have built-in GPIB or RS232 interfaces for communicating with host computers. This enables network communication between instrumentation and host computers without the need for additional peripherals, and in many industries, instruments are being used effectively. However, most of the monitoring systems for measuring instruments presented so far have been produced in a textual or two-dimensional environment. Therefore, there was a lack of field or flexibility in transmitting various information data from the instrument to remote users on the web, and the remote users had to take the effort of reinterpreting the monitored information through a series of efforts. Therefore, it is possible to move away from the monotonous monitoring methods in the form of text or two-dimensional graphics, and to implement a three-dimensional environment on the web using visual objects such as buttons, lighting effects, weighing devices, tanks, valves, motors, etc. There is a growing need for technology development to provide technology to users and to enable synchronization of a multi-user environment.

VRML (Virtual Reality Modeling Language) is an international standard language for implementing 3D graphics on the Internet. It is a tool that enables 3D representation of data transmitted from a server in a client's web browser, and provides an intuitive and unified interface. do. However, until now, no system has been proposed to enable three-dimensional monitoring through the Internet of instruments having RS232 interfaces installed in industrial and measurement sites using VRML.

Meanwhile, the prior art in this field is disclosed in detail in the following documents.

1) Seung-Hyun Lim, Wan-Jong Kim, Young-Shin Kong, Jae-Wook Jeon, "Remote Control System GUI Using Web", Joint Conference on Control, Automation, and Robotics Research, 1999.

2) Kyung Soo Jang, Dong Ryu Shin, "An Implementation of MMS based on WWW", KACC, October 1998.

3) Cha Suk-keun, "Control Interface using TCP / IP", Communication Network and Control Automation Technology.

4) Son Jae-bum, Jung Wan-kyun, Yeom-il Yeom, "Remote Control System", Advanced Robot System Technology.

5) Chang-geun Yeom, Kyung-hwan Park, "3D Interactive Virtual Space System Using VRML", Journal of the Korea Multimedia Society Spring Conference, February 1998.

6) Koh Young Deok, "VRML 2.0", Hye Ji Won, July 1998.

7) Bong Sun Kim, Hyun Dong Kim, Hong Sung Park, "Optimization of 3D Web Monitoring", KACC, Octorber, 1999.

8) Young-Soo Jung, Sang-Hoon Kong, Kyo-Il Lee, Young-Geun Han, "Development of Virtual Processing System and Remote Operation System Based on Internet", KACC, Octorber 1999.

9) Lee A. Belfore, II, Rajsh Vennam, "VRML FOR URBAN VISUALIZATION", Proceedings of the Winter Simulation Conference, 1999, pp. 1454-1459.

The present invention has been made to solve the above problems of the prior art, and an object thereof is to provide an internet-based three-dimensional remote monitor and control system.

More specifically, the present invention connects the operation data acquired at the industrial site to a computer system in the Internet environment near the site by using a Java application and Visual Basic to real-time the situation data of the site beyond the spatial and geographical limits in real time. It is an object of the present invention to provide an internet-based remote monitor and control system for a small PLC that enables the remote operation of the PLC via the Internet at the same time.

1 is an embodiment of an internet based remote monitor / control system in accordance with the present invention;

FIG. 2 is a detailed configuration diagram of the server system of FIG. 1.

3 is an execution structure diagram of an ASP.

4 is an illustration of Tiny PLC of Compile Corporation.

5 is an exemplary view of a connection waiting screen of a socket server.

6 is an exemplary view of a socket server screen after a user connection.

7 is an exemplary diagram of a PLC status data display screen displayed on a browser of a client after server connection.

8 is an example of a screen for displaying A / D conversion data in a PLC after connecting to a web server.

9 is an exemplary view of a data table represented by an ASP when the 'view data' button is clicked.

10 is another embodiment of a three-dimensional remote monitor / control system based on the Internet according to the present invention.

11 is a relationship diagram with VRML, EAI, and Java Applet.

12 is a flow chart of operations between server / client.

FIG. 13 shows an example of a three-dimensional multimeter displayed on a client web browser after connecting to a web server. FIG.

<Brief description of the main parts of the drawings>

20: Client 25: Web Browser Cosmo Player

100,200: server system 110: PLC

120: Visual Basic Socket Server 130: Web Server

140: Database Management System (DBMS)

150: ASP 160: Database

170: HTML 210: HTML, VRML, Java Applet

212: Java 214: Java Applet

216: VRML 218: Script Node / Multimeter Node

230: EAI 220: Visual Basic

300: multimeter 400: power supply

<First Embodiment>

Today, due to the rapid development of the information industry, the Internet is easy to use anywhere regardless of time and place, and the network speed is getting faster. In addition, the information can be provided using the Internet using only a web browser without the user installing other programs, and the information can be used regardless of the platform. Therefore, the application of the control device of the Internet can be said to have a great meaning. This application eliminates the need for operators to stay on site all the time and has the advantage of being able to monitor and control site data anywhere the web browser is running. The overall structure of the monitor and control system for a small PLC provided by the present invention is shown in FIG.

The overall system structure of the present invention is composed of a server 100 which is connected to the small PLC 110 and driven and a client 20 that is connected to the server 100 at a remote location.

<Server system>

The server 100 provides the operation data of the PLC to the remote user connected through the web browser in the client 20 and at the same time receives a command from the remote user and transmits it to the PLC. The structure of the server system has a structure as shown in FIG.

Web server

When the remote client 20 requests the necessary information through the browser, the web server 130 finds and sends an HTML (HyperText Markup Language) document corresponding to the requested information. This HTML document contains the Java Applet for exchanging data with the PLC and the code for accessing the database. Since the Java Applet is basically executed in the client 20 after being downloaded to the client 20, there is a security limitation in that it cannot read or write a file or a disk. Therefore, direct connection to the PLC 110 connected to the server 100 is structurally impossible. However, among the features of the applet also has a feature that can communicate with other applications in the system, such as the web server (130). In the present invention, the socket server 120 written in Visual Basic 6.0 serves as a bridge between the applet and the PLC 110. The socket server 120 reads the data from the PLC 110 and sends it to the applet via the IP number and the promised port number of the web server 130, and sends the data to the applet. It serves to send to the PLC (110).

In addition, the socket server 120 has a function of storing data measured from the PLC 110 in a database 160 file.

In addition, in the present invention, as shown in FIG. 2, the ASP 150 is used to interwork with the database 160.

Active Server Pages (ASP)

Generally, CGI, Servelet, and Server API can be used as server-side extension technology that can interoperate with the database. However, CGI has low performance and security weaknesses, and there are not many servers that fully support Servelet or Server API. Therefore, in the present invention, ASP, which is recently used for shopping mall or database interworking, is used. ASP is a server-side scripting language that runs on Windows-based web servers. The execution structure of the ASP is shown in FIG.

As can be seen in FIG. 3, ASP is a server scripting language. When HTML 170 is requested from the client 20, the server 100 executes a script engine operating as a DLL and executes all the scripts in the HTML 170. The execution result is included in the HTML document and sent back to the client 20.

<Client>

The client 20 does not have to use a separate program to the remote PLC 110, but simply finds and connects to a Uniform Resource Locator (URL) of the web server 130 through a web browser. When the server 100 is connected, HTML 170 including a GUI developed for manipulating the PLC 110 is downloaded from the web server 130 and the client browser executes this. The accessor may execute a Java Applet to monitor the current state of the PLC 110 and send specific data to the PLC 110. In addition, the data of the PLC 110 stored up to now can be viewed by driving the ASP 150.

Now, the server / client design described above effectively introduced to the industrial field to confirm the usefulness of the present invention A case in which the present invention is applied to a Tiny PLC (manufactured by Compile, Inc.) as shown in FIG. 4 will be described.

The Tiny PLC 110 has an RS232 interface for communication with the web server 130 and, if a prescribed protocol is used, the sequence control situation (A / D conversion value, auxiliary relay) inside the PLC 110 to the web server 130. , Input port) and the PLC output relay from the web server 130 can be driven. Therefore, in the present invention, it is possible to monitor the relevant data of the PLC (110) connected to the web server 130 on the browser of the remote user, and at the same time if the operation of the PLC (110) is not desirable, the PLC ( Design a system capable of turning on / off the output relay of 110).

In this embodiment, the web server 130 uses PWS (Personal Web Server) provided as a package in Windows 98 because the ASP 150 used for remote PLC data request basically operates in a Windows environment. In addition, a database file for storing the operation data of the PLC 110 on the web server 130 was created using MS Access.

FIG. 5 is a screen for executing a socket server on a PWS and waiting for a remote user to be connected. FIG. 6 is a view illustrating an accessor's IP and connection status, read / write mode, and read / write status when a request is made from two clients to the server. This is a screen where write values are displayed.

7 is a client browser screen displaying the A / D measurement values of the PLC and the status data (auxiliary relay status) inside the PLC after connecting to the server.

The GUI of FIG. 7 running on the client's web browser consists of two parts. One is to input / output data to the auxiliary relay and output relay of PLC through socket server after connecting with web server, and the other is to measure A / D conversion value measured in real time inside PLC from socket server of web server. This is the part that shows graph of different color. By default, A / D conversion values begin to display as soon as the connection with the socket server is established. The "View Data" button at the bottom of the screen allows you to view ASP-enabled data from a database file (such as data values up to three channels) by running an ASP on the web server when a remote user clicks on it.

8 shows a screen in which the three-channel A / D conversion value in the PLC is updated once per second and a screen in which data is written to the auxiliary relay of the PLC through the write mode. FIG. 9 shows a new screen when the "view data" button is clicked. A browser window is created, showing the screen displaying the contents of the database in a table format.

In the present invention, as a result of implementing an Internet-based remote monitoring and control system that can be applied to a PLC widely used as a controller of an industrial process, real-time monitoring and remote control of internal operation data of a PLC bited on a server by accessing a web server through the Internet. Could confirm that it is possible. However, the change of PLC internal data (change of output relay, etc.) from the remote is not desirable for the security level of the system. Therefore, the influence of real time monitoring data by authentication and network delay time related to the change of important data inside PLC is considered. Should be.

Second Embodiment

Today's factories and industrial sites use network monitoring to verify work. Monitoring work status in the factory saves managers the inconvenience of having to stay in the field and creates a lot of time and space efficiency because the situation of the site can be checked wherever internet communication is available. In addition, monitoring can be a good alternative to human effort in situations where humans have a difficult time or need to observe several areas in one place. The configuration of the multimeter 3D remote monitor system developed in the present invention is shown in FIG.

The 3D remote monitor system is composed of a server 200, a client 20, and a measuring instrument 300, and the Visual Basic program 220 driven by the server 200 reads measurement data from the measuring instrument 300. The VRML file and the Java Applet 210 enable 3D graphics processing in the client 20 connected to the server 200.

-VRML

VRML (216) is a language that expresses virtual reality. It is a term that started from VR (Virtual Reality), which has been studied for many years, and is a language that can implement a three-dimensional model through the Internet.

It is object oriented like the Inventor file format. The Inventor file format is one of the best languages for reading and recording objects. It can contain not only three-dimensional geometry, but also MIDI data, graphic data, and MPEG files, which are video data. Inventor defines a set of three-dimensional graphical objects as a separate object, called a node. VRML 216 also uses this node. Each node represents one object and they come together to form a VRML file representing a virtual space. In other words, the nodes of the VRML 216 have object-oriented characteristics so that 3D graphics can be easily represented.

In the present invention, by using the object-oriented features of the VRML (216) to design a system that can express the instrument 300 on a three-dimensional web browser. In addition to VRML (216), there are other ways to express 3D, such as Java 3D (212) or Open Inventor, but VRML (216) is an international standard for expressing 3D graphics on the Internet. In the present invention, since the browser, the authoring tool, the format conversion program, etc. supporting this are various, practical, and less influenced by the vendor, the present invention is also used.

VRML, JAVA, EAI

VRML 216 provides a script node that can dynamically drive the scene graph through interaction with the outside world. Here, the script node is a node that plays a logic role in the event flow and is mainly composed of JavaScript. These nodes send and receive events through route statements, and can define interoperability with the outside world by defining nodes and fields with 'DEF' statements. EAI is a communication protocol between Java Applet and VRML. Applet can exchange data with a VRML node defined as 'DEF' through EAI (230) protocol.

FIG. 11 illustrates a general operation between VRML and Java. In the present invention, a node named Multimeter is used to receive measured data from an instrument, and specific operations thereof are as follows.

First, define the Multimeter Node to be manipulated in VRML file with 'DEF' statement. Then, in java applet, the getNode () method is used to receive the reference value of the multimeter node in the form of string according to the EAI (230) specification, and each event is generated and sent to eventIns in the VRML world to obtain the current value of eventOuts. . In other words, java Applet receives the motion coordinate data through communication with the measuring instrument and makes the VRML world implemented dynamically by repeating the task of reflecting the event value for the dynamic position through the eventIn VRML Scenedp.

-server

When there is a connection from the client 20, the server 200 provides the user with a three-dimensional model of the multimeter written in the VRML 216. To do this, instrumentation applications written in Visual Basic 220, VRML, Java Applet, and HTML files must exist on the web server. The measurement related program written in Visual Basic functions to transmit data measured from the instrument 300 to the Applet class through a designated port. In fact, you can integrate these features in java, but the reason for using Visual Basic is that you can easily communicate with the instrument via RS-232 serial communication using the ActiveX Control feature. In addition, Java Applet and VRML file are used to interoperate to create 3D GUI environment. Web server includes HTML document for screen initialization when connecting to client.

Communication program operation

12 shows an operation flow between the server and the client. In FIG. 12, the operation sequence of the server / client is a method used in the communication program of the present invention and operates according to the operation sequence of the server and the client, but may vary slightly depending on the purpose and function of the program. The operation of the whole program is as follows.

First, when the web server is connected to the domain of the web server through the web browser from the client computer in a state waiting for the access of another user (s10) (s20), the web server sends an HTML file for initial screen setting to the client computer. At this time, VRML (.wrl) file and Java Applet (.class) file are embedded in the HTML document and transmitted together (s30).

The HTML document transmitted to the client is interpreted by the client computer to operate on the browser (s40). Up to this point, the root scene graph and the html file, which are not defined as 'DEF' nodes in the wrl file, are executed without any input from the instrument yet. In the same time zone, the instrument server (Visual basic) periodically waits for a client connection while reading the instrument's value (s50).

Next, the Java applet creates a socket for requesting measurement values from the server and generates a signal for requesting measurement values from the server (s60). When a data request from the client occurs, the server accepts the connection to the client (s70), creates a new socket for waiting for the connection of another client, and then passes the measured data to the connected client (s80). After receiving this data, the Java applet controls the VRML Node according to the EAI protocol (s90), and then displays the measured value in three dimensions in a web browser. After finally displaying on the screen (s100) and closes the socket (s110).

On the other hand, the server-side operation flow is as follows. First, the VBA initializes the measuring instrument (S210) and starts measuring (S220). The socket is created (s230), the socket is given a name (s240), and the client waits for a connection (s250). When the connection request comes from the client accepts the connection and waits for the connection by creating a new socket (s260). Since the connection is sent to the client to send the measured data (s270) and closes the socket (s280).

3D telemetry implementation

Monitoring of measurement data

Monitors on instruments connected to remote servers are critical in keeping track of their work. If the remote operator cannot grasp the work situation, the malfunction of the equipment in the instrument will have to be overlooked, and if it is a real industrial site, it may cause a fatal danger.

In the present invention, as a method for confirming the operation of the measuring instrument, a method of numerically calculating the measurement data of the multimeter and sending it back to the operation site is used to express it as a three-dimensional dynamic screen. Although not largely addressed in the present invention for multimeters, monitoring over the Internet has a network propagation latency problem. In monitoring the instrument and controlling the equipment from a remote control site, irregular propagation delays in the network can lead to inaccurate insight into the instrument's situation and can be a source of erroneous control or judgment. As such, these points should be taken into account when designing a monitoring system. Also, when dealing with 3D graphic data, complex graphics generate huge sized graphic sources, so consider how to handle them properly.

-3D multimeter experiment

In the present invention, the HP 34401A digital multimeter was used as a measuring instrument, and the voltage from the power supply unit 400 was measured. The server 200 was built using Visual Basic 5.0, Java2.1, and VRML 2.0, and used the Internet 3D Space Builder as a VRML authoring tool to create a three-dimensional image of a multimeter.

13 is a screen of the multimeter appearing on the client's web browser after connecting to the web server.

According to the present invention, it is possible to implement a 3D remote monitoring system based on a server / client structure on the Internet, which is a commercialized network using VRML, which is an internet 3D graphics standard language. In addition, experiments using a multimeter can express three-dimensional information in real time on the Web.

Claims (5)

In the system to monitor and control the operation status of the process in real time remotely through the Internet, A plurality of programmable logic controllers (PLCs) for controlling the process; Multiple instruments equipped with an RS232 interface for measurement of process parameters; A server system connected to the plurality of PLCs and instruments and connected to the Internet; And Internet-based remote monitor / control comprising a plurality of clients connecting to the server system via the Internet to monitor the operation of the process via data read from the server system and to control the process via the PLC as needed. system. The method of claim 1, wherein the server system A web server connected to the Internet to find and send an HTML document corresponding to information requested by the remote client; A database storing predetermined data including measurement data; A socket server communicating with the web server via an IP number and a promised port number, communicating with the plurality of PLCs via an RS232 interface, and storing data measured from the PLC in the database; An active server pages (ASP) connected to the web server and linked with the database to expand the server system; And And a database management system (DBMS) that manages the database and operates in conjunction with the ASP. 3. The Internet-based remote monitor / control system according to claim 2, wherein a socket server acting as a bridge between the applet and the PLC is created in Visual Basic so that the client directly connects to the PLC. In the system for measuring the operation data of the process in three dimensions remotely through the Internet, Multiple PLCs; A multimeter having an RS232 interface for reading predetermined measurement data through the plurality of PLCs; A server system connected to the measuring instrument and the Internet; And And a plurality of clients that obtain the measurement data read by the measuring instrument by accessing the server system via the Internet. The web server of claim 4, wherein the server system includes a measurement application written in Visual Basic, a VRML, a Java applet, and an HTML file in a web server to provide a three-dimensional model of the instrument written in VRML to a user when the client connects. Internet-based three-dimensional telemetry system characterized by.