The development of fieldbus technology has led to changes in the structure of traditional control systems. In heating systems, most regions in China currently rely on manual meter reading at each heating station, with data reported to the local heating company. Dedicated personnel are then responsible for recording, compiling, and analyzing the data. Consequently, the daily operational status of each heating company cannot be promptly reported to the heating management office. To ensure effective heating for residents, fieldbus technology plays a powerful role, not only enabling automatic meter reading but also timely data transmission to the heating management office. New Requirements for Heating Control Systems In China's energy structure, heating energy consumption accounts for a large proportion, and its energy-saving potential is considerable. This is mainly reflected in: energy waste caused by heating network imbalances; a lack of effective regulation methods in the heating system, preventing meaningful operational regulation and on-demand heating; unreasonable equipment matching; and excessively high operating costs, particularly the excessive power consumption of heating network circulating pumps, among many other aspects. Urban heating is crucial to the comfort of countless households. From the primary purpose of heating, an effective, sensitive, and automatically regulating system should be established, connecting the end user (heat exchange station), heating station, and heat source. This is essential to completely resolve irrationalities in the heating system. Therefore, a modern networked heating monitoring and management system must possess the following characteristics: ■ Reduced labor intensity; ■ Automatic meter reading at each heating station; ■ Heating companies can view real-time heating data from each station connected to the system; ■ Heating companies can also view and print historical trends and data from each heating station; ■ Stable and reliable system operation . Features of Fieldbus Technology Fieldbus technology is a digital, serial, multi-point communication data bus (IEC 6-1158) installed in manufacturing and process areas between field devices and automation devices in the control room. It can solve digital communication problems between various intelligent field instruments, controllers, actuators, and other field devices. Fieldbus communication can use wired or wireless methods to connect field devices and control units conforming to the same fieldbus standard to form a digital communication network. Its main features are: ■ Improved system accuracy and reliability, greatly simplified system integration, and easier maintenance; ■ Reduced control risks, decentralized control functions, and improved system response speed; ■ Saved a large amount of signal cables; ■ Field equipment has self-diagnostic functions, making it easy to determine the location of faults; ■ Open technical standards, allowing users to choose the best option. Control System Composition The heating stations in this system are distributed within a radius of 400 square kilometers, and are geographically dispersed. Therefore, the heating company automatically polls all heating stations under its jurisdiction via a dial-up network to collect field data in real time. Simultaneously, the data collected by the heating company is transmitted in real time to the SQL data server of the heating office via wireless microwave data transmission. The system consists of two parts: a data management and analysis system and a real-time monitoring system. This section mainly introduces the real-time monitoring system. The real-time remote monitoring system (within each heating company) collects data from each heating station via a dial-up network. System Configuration This system uses a dial-up connection via MODBUS bus to monitor various remote slave devices from the monitoring center, recording the collected data for transmission to the data management and analysis system. Monitoring Center The main equipment at the monitoring center consists of a computer and a modem, exchanging data with each heating station via a dial-up network. The monitoring software uses the popular IFIX industrial control software from Intellution, Inc. (USA). The monitoring software displays various data collected by the hardware system, such as pressure, temperature, and flow rate, in the required manner. Features of IFIX software: ■ Stable and reliable. ■ User-friendly interface. ■ Good real-time performance. ■ Alarm function; generates alarm information on the screen when the network connection fails. Remote Slave Devices Each heating station in this system uses a WAGO fieldbus device to receive instrument signals from the field and process them into digital signals for transmission to the host computer for display. This fieldbus device consists of three parts: a MODBUS fieldbus controller, an input/output module, and a terminal module. The fieldbus controller uses the 750-816, whose MODBUS fieldbus interface allows direct connection to a modem to automatically respond to requests from the monitoring center and transmit data. In addition, the controller has certain control functions, enabling local data acquisition and processing, improving system real-time performance. WAGO's fieldbus input/output modules are characterized by high precision and high reliability. Their well-designed modular structure allows for tool-free disassembly of I/O modules. Powerful diagnostic functions make system debugging and maintenance easy. This modular structure significantly reduces design, installation, debugging, and maintenance costs, simplifying previously cumbersome schematic and wiring diagram design. A terminal module indicates the end of a slave configuration. The system has 76 such fieldbus devices. Because the system uses a dial-up network bus configuration, adding or removing nodes is easy, and each node uses modular fieldbus devices requiring no backplane. Therefore, adding or removing modules on the same node is also very easy and requires minimal space. This feature gives the system strong scalability without increasing wiring hassles or costs. Field Actuators Field actuators are further divided into detection and execution sections. Field instruments complete the first step of the monitoring process, converting the measured physical parameter signals into electrical signals. Examples include pressure gauges, level gauges, flow meters, and pressure transmitters. The converted electrical signals are then transmitted to the fieldbus input/output devices. Conclusion In recent years, fieldbus technology has developed and become widely used, especially in the automation industry. This heating network project has opened up a new world for the field of heating automation. The wireless LAN used in this project is in line with the trend of the network era. Operation has proven that this heating network project has not only improved heating efficiency but also saved on various dead zones and insurmountable difficulties that occur every year during the heating season, providing a solid guarantee for people's heating needs and the work of heating companies during the heating season!