Abstract: Based on practical engineering experience, this paper analyzes the current status of elevator monitoring systems both domestically and internationally. Combining computer configuration technology, it proposes a scheme for designing an elevator monitoring system based on MCGS industrial control configuration software. This system uses computer-generated animations to simulate elevator operation, directly, intuitively, and accurately reflecting the actual operating status of the elevator. It promptly alarms for faults in the elevator system, analyzes and judges the causes of faults, and allows direct computer control of elevator operation.
introduction
With the acceleration of urbanization, elevators have become an indispensable means of transportation in people's daily lives, and their operational reliability has become a focus of attention. Therefore, the development and research of elevator monitoring systems has significant practical implications. The purpose of elevator monitoring is to enhance elevator management with minimal personnel, providing a more intuitive, clear, and accurate view of elevator operation status, thereby offering multiple possibilities for maintenance and fault diagnosis and significantly improving system efficiency. This paper, starting from practical engineering considerations, comprehensively analyzes the current status of elevator monitoring systems both domestically and internationally. Combining computer configuration technology, it proposes a scheme for designing an elevator monitoring system based on MCGS industrial control configuration software. The system uses a network to collect real-time elevator data through the computer's serial port, and uses computer-generated animations to simulate elevator operation, directly, intuitively, and accurately reflecting the actual operating status of the elevator. It promptly alarms for faults in the elevator system, analyzes and judges the causes of faults, and allows direct computer control of elevator operation.
1. Overall System Design
Figure 1 shows the overall system block diagram. In the figure, the main control computer is connected to multiple PLCs through an RS-232/485 converter. Each PLC is assigned its own address to identify itself. In this way, the host computer can communicate with all the PLCs (lower computers) connected below through the 485 communication line to realize distributed control of the elevator.
Figure 1 System Overall Architecture Diagram
2 Development Environment
The system's upper-level computer monitoring component utilizes MCGS (Monitor and Control System) configuration software. MCGS is a Windows-based configuration software system for quickly constructing and generating upper-level computer monitoring systems. MCGS provides users with a complete solution and development platform for solving practical engineering problems, capable of performing functions such as field data acquisition, current and historical data processing, process control, animation display, trend curves, and report output. The MCGS software system consists of two parts: a configuration environment and a runtime environment. The configuration environment is essentially a complete set of software tools that helps users design and construct their own application systems. The runtime environment runs according to the configuration project constructed in the configuration environment, in the manner specified by the user, and performs various processes to achieve the goals and functions of the user's configuration design. The runtime environment itself has no meaning; it must be used together with the configuration result database to constitute the user's application system. Once the configuration work is completed, the runtime environment and the configuration result database can run independently on the monitoring computer, leaving the configuration environment. The MCGS configuration runtime environment is shown in Figure 2.
Figure 2 MCGS Configuration and Operation Environment
3. Elevator monitoring and analysis
The PLC can collect elevator operating status parameters in real time, such as commands, calls, operating modes, and door opening/closing signals; dynamically display the elevator's operating status, such as direction, position, door opening/closing, and leveling; promptly analyze and diagnose faults, alert and inform maintenance personnel, and simultaneously handle emergencies.
4 Design Process
(1) Create a monitoring interface. It is worth noting that 16 elevator monitoring screens were created in this process. This is to achieve the purpose of real-time monitoring. After entering the operating environment, each elevator may be on any floor. These 16 windows list the possible initial screens of the elevator. After entering the operating environment, the screen can be called according to the specific conditions.
(2) Establish a real-time database. The real-time database is the core of the MCGS system and serves as the data exchange and processing center for all parts of the project. It connects all parts of the MCGS project into an organic whole. During this process, various internal and external call signals corresponding to the elevators are defined for use in attribute settings and programming.
(3) Configure screen attributes. Connect the various switch-type or numerical variables defined in the real-time database with the corresponding buttons, indicator lights, etc. in the monitoring screen so that the animation can move as required.
(4) Communicate with the PLC. In the device window, select the COM port programming protocol to establish a device channel, and match the various variables defined in the real-time database with the corresponding I/O allocations in the PLC. Monitoring is achieved by reading and writing signals in the PLC. This is the most critical and important part of the entire process.
(5) Alarm Analysis. Alarm analysis is a crucial component of the elevator monitoring system. Various malfunctions may occur during elevator operation, requiring the monitoring system to detect the fault type and trigger an alarm. The main alarm scenarios covered by the system include: ① The elevator fails to stop at the nearest floor for some reason; the solution is to move the elevator up or down to the nearest floor. ② The elevator cannot open or close its doors properly; the doors fail to close correctly after reaching the designated floor, requiring fault detection to notify relevant personnel for repair. ③ The elevator exceeds its up or down limit; the solution is to initialize the elevator to the first floor. ④ Overloading occurs in the elevator car, accompanied by an alarm to inform the user. Additionally, an emergency button is located inside the elevator car; users can press this button to notify the monitoring system in case of an unexpected malfunction, facilitating prompt repair.
(6) Complete the script program. The script program includes the elevator door control section, the car going up or down section, the section for entering the operating environment and calling the screen, and the alarm section.
5. System Debugging
(1) Offline debugging of the monitoring system
After creating the monitoring interface, the first step is offline debugging to ensure the elevator responds to internal and external call signals, moving up or down according to the signals, and the doors open and close in a timely manner. This requires excellent programming skills and a thorough understanding of the MCGS scripting environment and its syntax. To ensure the elevator functions correctly, the animation interface properties must be set perfectly and correspond to the data variables in the real-time database. Then, the script program controls the screen's operation. Since monitoring systems for parallel or group-controlled elevators may be encountered, various elevator operation scenarios and factors such as signal overlap must be considered. Initially, a problem may arise where pressing the first-floor internal call signal for elevator 1 causes it to open its doors. Pressing the second-floor internal call signal causes the elevator to rise to the second floor but immediately return to the first floor, resulting in the elevator constantly oscillating between the first and second floors. This is because the first-floor signal is not cleared. Because there are many signals from the two elevators, various scenarios must be considered simultaneously to ensure no signal conflicts.
(2) Debugging communication with PLC
After the initial screen setup, communication debugging with the PLC began. First, the serial communication parent device was selected, and various attribute settings were configured. Then, the PLC device was selected, input and output registers were established, and channel connections were established. Many problems were encountered during the connection process. For example, after setting various channel values, the communication flag always showed 1, indicating that communication with the PLC was not successful. If communication was successful, the communication flag should show 0. After multiple tests, this problem was finally solved. Next was the communication issue with multiple elevators. Although the settings were the same, only one elevator could communicate normally. Analysis revealed that the PLC programming protocol selection was incorrect because the PLC programming port is for one-to-one communication, while the COM port is for one-to-many communication. After much effort, simultaneous communication between multiple PLCs was finally achieved. Finally, monitoring and controlling the PLC's operation was addressed. At this point, it was simply a matter of selecting the correct signal as the programming object. However, signal selection requires some experience; otherwise, the program cannot be simple and practical.
6. Conclusion
MCGS configuration software is powerful, easy to operate, and user-friendly. Ordinary engineers can quickly master the design and operation of most engineering projects after a short training period. The innovation of this article lies in its ability to monitor the elevator's dynamic operating curves on the MCGS-configured monitoring interface on a host computer. It can reflect the elevator's operating status and comfort in real time, and can proactively analyze potential elevator malfunctions, allowing engineers to focus on solving the engineering problems themselves. Therefore, developing a remote elevator monitoring system has significant practical implications.
