Diesel generator sets are widely used in locations without mains power supply and requiring uninterrupted power supply, such as base stations and equipment rooms in telecommunications, power, and broadcasting systems, as well as power supply systems in banks, hospitals, and other institutions. Within telecommunications systems, a county-level bureau typically manages multiple power supply equipment rooms. These rooms may be located in urban areas or remote mountainous regions; some are manned, some unmanned, but all require uninterrupted power supply. Generally, each equipment room has one to several diesel generator sets as backup power for mains power, or several sets mutually act as primary and backup power sources. Therefore, it is crucial to implement automated computer monitoring and unified management of these diesel generator sets. This helps reduce the workload of on-duty personnel, improve work efficiency, and enhance management levels. A centralized monitoring center is set up within the county-level bureau. The monitoring host uses the public telephone network to achieve remote real-time automatic monitoring and management of diesel generator sets at various subordinate base stations. The system is easy to build, simple to implement, reliable in use, and suitable for practical needs, leading to its widespread application. 1 System Structure The system structure of the remote monitoring platform for diesel generator sets is shown in Figure 1. The diesel generator set is connected to the telephone line via a modem, and at the other end of the telephone line, it is connected to the RS-232 serial port of the monitoring host via another modem. Many county-level bureaus and lower-level base stations have SDH channels for communication. If an additional RS-232 serial port is available, data can also be transmitted through the SDH channel, thus eliminating the need for modems at both ends of the telephone line, equivalent to a direct RS-232 serial cable connection. If multiple diesel generator sets within a lower-level base station need to be monitored, each generator set can be allocated a telephone line, and each can use one RS-232 serial port on the monitoring host, provided the telephone line allows. If telephone lines are limited, the diesel generator sets within the base station can be connected to a network via an RS-485 bus. After passing through an RS-485/RS-232 converter, a modem is connected (see Figure 2), and the system connects to the monitoring host via a single telephone line. This only occupies one RS-232 serial port on the monitoring host. Each generator set is assigned an address, and the monitoring host distinguishes between them by address, monitoring each set in turn via the same telephone line. However, this will reduce the response speed of the monitoring system. The RS-485 bus is a two-wire half-duplex serial bus that uses twisted-pair cable to transmit data in a balanced differential manner. Its main features include: high transmission rate, up to 10 Mbps; long transmission distance, up to 1200 meters; and strong anti-interference capability, capable of driving 32 nodes over long distances in noisy environments. 2. Diesel Generator Set Monitoring Module Each diesel generator set is equipped with a monitoring module, allowing for computer monitoring of the generator set via serial port. Various signals are retrieved from the diesel generator set's electrical control box. We selected the 80C552 microcontroller as the control core of the monitoring module, employing large-scale integrated circuits and incorporating advanced design technologies. The monitoring module features dual watchdog circuits to ensure automatic recovery in the event of an unexpected system crash, which is crucial in unattended operation. The diesel generator set monitoring module measures operating parameters such as three-phase voltage, three-phase current, generator frequency, generator speed, oil pressure, coolant temperature, fuel level, generator starter battery voltage, and output power, and sends these parameters to the monitoring host as needed. Sensors for parameters like coolant temperature and oil pressure are generally non-linear, and the sensors used by different diesel generator set manufacturers vary significantly. The monitoring module stores data tables sent from the monitoring host and linearizes the collected parameters such as coolant temperature and oil pressure based on these tables to adapt to different sensors. The monitoring module has a non-volatile memory that can store a large amount of operating and control parameters. When the measured operating parameters exceed the set upper and lower alarm limits, the monitoring module controls various actions of the diesel generator set according to complex control logic: starting, stopping, ATS switching, etc., and reports various alarm information and various statuses of the diesel generator set (automatic/manual status, running/stopping status, mains power/diesel generator ATS status, diesel generator/diesel generator ATS status) to the monitoring host. The monitoring host can also remotely control the generator set to start, stop, perform emergency stop, switch between mains power/diesel generator ATS or diesel generator/diesel generator ATS, etc., as needed. All settings of the diesel generator set monitoring module can be completed on-site via the panel keypad, or remotely via serial port from the monitoring host. The monitoring module provides both RS-232 and RS-485 interfaces, and is available in two models using the China Telecom Administration protocol and the MODBUS protocol. It employs a 10-bit asynchronous serial communication method (1 start bit, 8 data bits, 1 stop bit, no parity bit), with a data transmission rate selectable from 1.2kb/s to 19.2kb/s. The monitoring host and the monitoring module exchange data in a strict master-slave manner (the monitoring module only returns corresponding data after receiving a command from the monitoring host, and does not actively send data to the monitoring host). This design is very suitable for building our diesel generator set remote monitoring platform. Diesel generator set monitoring modules have been developed into a series of products with varying functionalities to meet different needs. The monitoring module itself has a flexible structure and is easy to expand its functionality. 3. Communication Protocols We use two communication protocols: the China Telecom Administration communication protocol and the MODBUS communication protocol. The China Telecom Administration communication protocol refers to the "Communication Protocol for Front-End Intelligent Devices of the Centralized Monitoring and Management System for Power Supply, Air Conditioning and Environment of Telecommunication Bureaus (Stations)" issued by the China Telecom Administration, and the encoding method is ASCII. The information transmission method is asynchronous, with 1 start bit, 8 data bits, 1 stop bit, and no parity. The transmission baud rate is selectable at 19.2KB/s, 9.6KB/s, 2.4KB/s, 1.2KB/s, 0.6KB/s, and 0.3KB/s. The encoding and information transmission methods of the MODBUS communication protocol are the same as those required by the State Administration of Telecommunications. The MODBUS protocol is described as follows: Command format: AA, CC, SSSS, WWWW, LRC, CR, LR AA: Address (two bytes); CC: Command (two bytes); SSSS: Data address (four bytes); WWWW: Data (four bytes); LRC: Checksum (two bytes); CR: Carriage return; LR: Line feed. Response format: AA, CC, RENUM, DATA, LRC, CR, LR RENUM: Number of bytes returned in response data; DATA: Return data; The rest of the explanation is the same as the command format. 4. Serial Port Expansion A typical county-level bureau manages several subordinate stations. If a time-sharing monitoring scheme is used, where the monitoring center uses only one telephone line, the monitoring host dials to connect to one subordinate station, monitors briefly, disconnects, and then dials to connect to another station, the system response time becomes too slow when there are many stations, making real-time monitoring difficult. Therefore, the monitoring center allocates a separate telephone line to each subordinate station, simultaneously connecting and monitoring all stations. However, the system computer used as the monitoring host usually only has two RS-232 serial ports, which is insufficient and needs to be expanded. Using MOXA's series of multi-serial port cards (the C168H eight-serial port card is commonly used) can easily expand the number of RS-232 serial ports to the required number, and the operation of these expanded serial ports is independent. The multi-serial port card itself comes with a rich function library and various tools, supporting popular programming languages ​​such as VB, Delphi, and C++, which can be directly called for programming convenience. However, it should be noted that the function library only supports the serial ports on the serial port card. Using the communication controls provided by the programming platform, the RS-232 serial ports on the serial port card and the computer itself can be manipulated equally. Due to the multitasking capabilities of the Windows operating system, the monitoring platform software can be carefully designed to simultaneously manipulate these RS-232 serial ports to monitor various lower-level generator stations in parallel, achieving real-time monitoring (if a lower-level generator station has more than one diesel generator set that needs monitoring and is connected via RS-485, then these generator sets still require time-sharing monitoring). 5. Remote Monitoring Platform Software The diesel generator set remote monitoring platform remotely controls, signals, and measures distributed diesel generator sets, monitors their operating parameters in real time, monitors and handles faults, records and processes relevant data, thereby achieving minimal or no human intervention and centralized maintenance. The remote monitoring platform software consists of two parts: monitoring software and interface construction software, and the entire software is developed using Delphi 5.0. The remote monitoring platform software can also be used to monitor other devices. The remote monitoring platform software has two versions based on the communication protocol: Version A conforms to the General Administration of Telecommunications' communication protocol, and Version B conforms to the MODBUS communication protocol, suitable for monitoring monitoring modules of different protocol models. The remote monitoring platform software has low requirements for both hardware and software environments; a standard Pentium machine with 16MB of RAM and a Chinese version of Windows 95 or later can run it normally. 5.1 Interface Construction Software Because our diesel generator set monitoring modules are a series of products, the monitored parameters vary. Even when using the same model of monitoring module, different users may have different numbers and names of monitored parameters. To avoid redundant software development and for ease of on-site installation and debugging, we developed an interface construction software. Based on the provided software manual and corresponding communication protocols, even users can easily design a monitoring interface for a specific diesel generator set. The number of monitored parameters, parameter names, fonts, colors, backgrounds, etc., can all be customized according to needs and personal preferences. After designing a monitoring interface and generating the interface file, specify the corresponding interface file for each monitored object. The monitoring software automatically loads these interface files, converts them into an interface, and monitors the corresponding diesel generator set. 5.2 Monitoring Software The functional block diagram of the monitoring software is as follows (Figure 3): After completing the necessary parameter settings, the monitoring software establishes connections with the diesel generator sets to be monitored, and simultaneously operates multiple RS-232 serial ports to send and receive data, monitoring the diesel generator sets. The response time is consistent with the response time of monitoring only one unit, approximately 2 seconds to complete a real-time data refresh. If multiple generator sets in a station are connected to the monitoring host via an RS-485 network and a telephone line, the monitoring software monitors these generator sets in turn, with a data refresh time = (number of generator sets on the same RS-485 network x 2) seconds. The monitoring software collects alarm information from each diesel generator set and generates report files for printing, saving, or uploading. Main Monitoring Unit Selection: The navigation tree window clearly displays the structure of the entire monitoring platform system: how many stations are in the system, how many diesel generator sets are in each station, whether the station and the monitoring host in the monitoring center are connected via MODEM dial-up communication or direct RS-232 serial cable connection, and how many generator sets are currently under monitoring, etc. Clicking on a unit icon will bring its monitoring interface to the forefront as the main monitoring interface. Here, you can monitor the unit's status and perform control and parameter settings. Dial-up and Hang-up: Connect all monitored stations to their respective designated phone numbers. After the work is completed, disconnect all connected stations. All stations can operate automatically simultaneously or independently. The system has a timed automatic monitoring function, automatically dialing and connecting at set times, then disconnecting after the monitoring period. If data is transmitted via an SDH channel, it's equivalent to a direct cable connection via an RS-232 serial port, eliminating the need for dial-up and hang-up functions. System Parameter Settings: Configure the stations to be monitored, along with phone numbers, unit addresses, timed dialing, corresponding RS-232 serial ports, and communication baud rates. Module Parameter Settings: For each diesel generator set monitoring module to function correctly according to its intended purpose, numerous parameters must be set: generator set address, communication baud rate, upper and lower alarm limits, sensor linearization parameters, monitoring module system parameters, and many other parameters related to the diesel generator set's operation and control. Alarm Records: When an alarm is generated for a diesel generator set, its corresponding monitoring interface pops up to the foreground as the main monitoring interface, simultaneously emitting an audible alarm and saving the alarm record. Alarm logs are saved in text format in the "Alarm Records" folder, with one alarm file generated daily, named after the current date. Alarm files are periodically deleted. Report Printing: Individual alarm logs can be printed, or alarm logs from all generator sets for the day can be compiled into a report and printed for archiving or submission as the day's work log. 6. Conclusion Since our developed remote monitoring platform system for diesel generator sets was put into use, it has been installed and used in multiple county-level bureaus in provinces (regions) such as Guangxi, Anhui, and Xinjiang. Although the specific conditions of each region are somewhat different, and the system construction also varies, according to user feedback, the remote monitoring platform systems are easy to operate, stable in operation, and have improved work efficiency and management level. User feedback is generally satisfactory. It is believed that as the telecommunications system gradually expands its computer-automated monitoring and transformation of existing diesel generator sets, the usage of this remote monitoring platform system for diesel generator sets will see a significant increase. References: 1. MOXA Software CD-ROM 2000 2. Communication Protocol for Front-End Intelligent Devices of Centralized Monitoring and Management System for Power Supply, Air Conditioning and Environment of Telecommunications Bureaus (Stations) of the State Administration of Telecommunications, 1999 3. Zeng Jie and Wang Haidong, eds., Delphi 5 Advanced Programming Examples Explained, National Defense Industry Press, 2000 4. Wu Kuanming, ed., 80C51 Series Microcontroller System Principles, Functional Integration and Application, Beijing University of Aeronautics and Astronautics Press, 1995