Abstract : Based on the analysis of the current status and requirements of the production scheduling system of a coking plant, a monitoring system scheme based on FIX configuration software and CAN bus technology was designed and implemented in an engineering project. The results show that the system is reliable, advanced, and economical. Keywords : Configuration software, Fieldbus, DDE, CAN bus, FIX 1. Introduction Monitoring configuration software is a product of the development of computer technology and monitoring technology. The concept of "configuration" only became widely known among production automation technicians with the emergence of distributed control systems. Monitoring configuration software is a software platform tool oriented towards monitoring and data acquisition, with rich settings, flexible usage, and powerful functions. When monitoring configuration software first appeared, the human-machine interface was its main component. With its rapid development, real-time databases, real-time control, SCADA, communication and networking, and open data interfaces for extensive support of I/O devices have become its main features. The main purpose of configuration software is to allow users to generate application systems suitable for their needs without modifying the software source code, greatly shortening software development time, reducing development costs, and providing powerful and reliable operation. Fieldbus is a special network technology. According to the IEC 1158 definition, a fieldbus is "a serial, digital, bidirectional, multi-branch communication network between field devices, instruments, and automatic control devices and systems installed in the production process area and in the control room." Like other networks, fieldbus network systems also possess several OSI layer protocols, meaning they share the same attributes as ordinary network systems. However, fieldbus is a network developed specifically for industrial environments, thus offering unparalleled advantages over other networks in industrial settings. 2. Overall Scheme Design 2.1 User Requirements The goal is to provide real-time data to the coking plant's dispatchers, allowing them to intuitively observe production technology data and equipment operating status data from all workshops within the plant from the dispatch room. This real-time data is crucial for efficiently utilizing human and material resources and achieving automation. Plant-wide production data can be monitored, processed, stored, printed, and alarmed for exceeding limits in the dispatch room. The monitoring computer software requires a graphical human-machine interface. 2.2 Bus Selection Currently, the main fieldbuses include: Foundation Fieldbus, Lonworks bus, PROFIBUS bus, and CAN bus. Through comparative analysis, we ultimately selected the CAN bus. The CAN bus, introduced by Bosch in Germany, has been adopted as an international standard by the ISO international standards organization. It is supported by major companies such as Motorola, Intel, Philips, Siemens, and NEC, and is widely used. The CAN bus was also one of the earliest fieldbuses to enter my country, and its application technology and related products have reached a mature stage. At a communication rate of 5kb/s, no repeater is needed, and the transmission distance can reach 10km, fully meeting our wiring requirements in the factory area. Its transmission medium is twisted-pair cable. It can connect up to 110 devices, meeting the requirements for the number of data acquisition points in the factory area. The CAN bus operates in a multi-master master-slave mode, where any node on the network can actively send information to other nodes at any time, without master-slave distinctions, providing flexible communication. This feature allows for the easy construction of multi-level backup systems. Each frame of information undergoes CRC checksum verification and other verification measures to ensure an extremely low data error rate. Based on these characteristics, we believe that the CAN bus is a reliable, efficient, and mature technology that can meet engineering requirements. 2.3 Configuration Software Selection Based on customer requirements—a user-friendly interface and powerful software functionality to facilitate future development—we selected Intellution's FIX software. According to the PCWEEK Special Report, the top-ranked industrial control configuration software in the world are: Intellution's FIX Dmacs for Windows, Wonderware's Intouch, USDA-TA's Factorylink, IBM's Plantworks, Heunristics' Onspec, Iconics' Genesis, and Intec Controls' Paragon. These software programs generally support field devices from world-renowned manufacturers. Considering both performance and the manufacturer's requirements, this system adopted FIX configuration software. FIX software integrates control technology, human-machine interface technology, graphics technology, database technology, and network technology, including components such as dynamic display, alarms, trends, control strategies, and control network communication. It provides a user-friendly interface, allowing users to generate their required application software without writing extensive code. 3. System Structure The coking plant industrial monitoring system consists of an RSM module, shielded twisted-pair cables, three host computers, two printers, and a projector (as shown in the diagram above). During normal operation, the two host computers work independently, with the two printers connected to them respectively. The third computer serves as backup data and connects to the projector, reading data from either host computer's database. If one host computer malfunctions, it reads data from the other. After the malfunctioning host restarts, it copies data from the other host computer, ensuring complete historical data. The CAN bus communication card and intelligent acquisition module in the PC are products of the domestic company, Huakong. However, FIX does not support Huakong's equipment, requiring Huakong's software to perform the acquisition function, while other functions are handled by FIX. Communication between FIX and Huakong's software uses the DDE method. After configuring the various acquisition modules in the field, HUCS collects data from the hardware in real time and sends it to Huakong's HKDDE server. FIX then retrieves the data from the server through the DDE client for further processing. 4. Software Design 4.1 Interface Design FIX provides powerful human-computer graphic editing functions, with its own material library and many examples. We used both the graphic elements in its material library and the graphic elements in the examples to design a three-dimensional interface. The main selection screen has twelve buttons, including coke oven gas and blast furnace gas from coke ovens one to four, coke oven number five, old depressurization, new depressurization, central pump room, and purified Yellow River water, as shown in Figure 2: [align=center] Figure 2 Main Screen[/align] Each button is represented by a bitmap, with corresponding descriptive text added below the button. Each button was programmed with corresponding command statements so that clicking it would pop up the corresponding second-level screen. The second-level screen contains the pipeline connection diagram and simulated sensing elements on the pipeline. The simulated sensing elements have nameplates, and using FIX's data link control, the field data can be displayed on the nameplates in real time. At the same time, when the user clicks the nameplate, a real-time curve screen of this collection point pops up, and the dispatcher can monitor the changes in this curve. The real-time curve display includes a multi-curve view, three historical curve viewing buttons, a historical report button, and a return button. The three historical curve buttons represent 20-minute, 8-hour, and 24-hour curves. FIX provides the function of outputting reports using Excel, which transmits data to the Excel application via a DDE server. We wrote a program using FIX's scripting language. Clicking the historical report button runs this program, automatically starting the DDE server program DMEDDE.EXE, and then opening the Excel program to perform report output. 4.2 Database Design The process of FIX obtaining data from the hardware is as follows: First, the O/I driver (this software uses the FIX Dynamic DataExchange I/O driver) reads data from the I/O and transmits it to the specified address in the Driver Image Table (DIT); then the Scan, Alarm, and Control (SAC) program reads data from the DIT, processes it, and transmits it to the process database; the internal database access function reads data from the database and transmits it to the application software that needs the data. Therefore, the database is the core of FIX. Screen editing, alarm functions, curve display, and other functions all rely on the database, and the quality of the database design directly affects the implementation of each function. FIX software provides different types of blocks, each performing a unique function. The purpose of generating a database is to link these blocks in a specific order to complete a particular task. A chain can perform functions such as inspection, automatic alarm, data acquisition, and process control. A database includes many chains to perform different functions. Because the database contains a lot of information, only two examples are given below for brief explanation: Example 1: The No. 1 coke oven acquisition point PIC202 is an analog signal, so the first-level block is the analog input block. By entering some data in the property dialog box of this block, a certain function can be completed, which is very convenient. The point name of this point is defined as J1PIC202. Because the data is read from the DDE client, the device in the hardware characteristics column should be DDE, and the I/O address is =hkdde|var!aio.pv; the engineering units are defined as: lower limit 0.00kpa, upper limit 4.00kpa; scan time is 1 second; the successor block of this node is the extended trend block J1PIC202ETR. This chain is now established. During runtime, the Scan, Alarm, and Control (SAC) program executes the instructions of each block at defined time intervals to complete the defined functions. For example, analog acquisition point PI401 requires alarm information, so the analog alarm block is selected as the first-level block. In the alarm column, the "Allow Alarm" option is selected, and the value of this analog quantity when a high alarm occurs is entered. Two contact names are defined: J1PI401H.F_CV and J1PI401L.F_CV, corresponding to the high and low limits respectively. When the limit is exceeded, the values ​​of J1PI401H and J1PI401L are set to 1. J1PI401H and J1PI401L are actually two switch alarm blocks with SIM hardware characteristics. The relationship of this chain can be illustrated by Figure 3. [align=center] Figure 3 Alarm Chain Structure Diagram[/align] 4.3 Historical Trend Display FIX completes the historical trend display function through three independent programs: historical definition, historical acquisition, and historical display. When designing the system, first define all the data collection points that need to be recorded in the history definition; then, ensure that the history acquisition program runs continuously during system operation and stores the collected data on the hard drive; finally, when the user needs to observe the historical data collection, use the corresponding pen in the history display program to display the data graphically on the interface. 4.4 Data Backup FIX provides a historical data backup function, which can flexibly and conveniently store data according to the user's definition and specified requirements. To use FIX's historical data, FIX must first collect the on-site quantities and store them on the hard drive, and then share the historical data with the DDE client program through its own DDE server. This system uses EXCEL as the DDE client program. The basic flow is shown in Figure 4: [align=center] Figure 4 Data Flow Diagram[/align] 5. Conclusion In this coking plant measurement and control system, CAN bus technology and FIX configuration software are perfectly combined. The system operates stably and reliably, has strong anti-interference capabilities, and is simple and convenient to operate, which is very popular with users. Therefore, this solution has practical promotion value. References: 1. Wei Ruixuan, Han Chongzhao, et al., Real-time Measurement and Control Network for Large and Complex Industrial Sites Based on CAN Bus Components, Industrial Instrumentation and Automation Devices, 2000.6 2. Wang Yan, Zhang Fuen, Current Status and Development of Fieldbus Technology, Electronic Devices, 2001.3 3. Wang Xinying, FIX32 Architecture and Application of Industrial Control Configuration Software, Microcomputer Information, 2001(17) 4. Liu Xiaoqiang, et al., Secondary Development and Application of FIX Configuration Software in Microcomputer Monitoring, Coal Science and Technology, 2000.2