Abstract: This paper first introduces the significance of applying the elevator remote monitoring system technology, then presents the composition structure of the elevator remote monitoring system, and focuses on introducing the hardware composition of the data acquisition terminal and its main functions. Finally, it introduces the software design of the acquisition terminal and the host PC in detail. Keywords: elevator; remote monitoring; data acquisition [b][align=center]Design of Remote Elevator Monitory System Chen Fei 1 Yang Huajiang 1 Jiang Bo 2 (1. Xinjiang Uygur Autonomous Region Special Equipment Examination Research Institute, 830000; 2. Xinjiang University, 83008)[/align][/b] Abstract: This article first introduces the significance of elevator remote probe system technology, then gives the composition structure of the elevator remote monitoring system, and pays great attention to introducing the hardware constitution of the data acquisition terminal, and completes the major functions. The communication procedure and the software flow chart between the data acquisition terminal and the remote PC are presented. Key words: elevator; remote monitoring; data acquisition 1 Introduction With the rapid development of the national economy, there are more and more high-rise buildings in large and medium-sized cities, and the number of elevators, an essential piece of equipment, has also surged. Because it is directly related to the safety of users' lives, the state stipulates that a special quality supervision department must conduct mandatory testing on them every year. Traditional annual inspection methods involve sending dedicated staff to the site to check elevator duty records and manually inspect various indicators. This is time-consuming, labor-intensive, and fails to objectively reflect the long-term condition and performance of the elevators. The remote monitoring system developed by the author installs a data acquisition terminal at the operating site of each elevator, continuously monitoring and recording the elevator's operating status 24 hours a day. When an annual inspection is required, historical and real-time data from elevators distributed across different locations in the city are remotely retrieved via telephone line to the quality supervision department's upper-level management computer. Dedicated evaluation software then analyzes the elevator's operating status, thereby objectively and accurately assessing its performance. 2. System Composition Diagram The system composition diagram is shown in Figure 1. The system consists of a remote upper-level management computer and multiple data acquisition terminals. Each data acquisition terminal is connected to one elevator, collecting various operational statuses of the elevator in real time. The data is analyzed and processed, and elevator fault information is saved to non-volatile memory. A remote host computer manages and evaluates elevator performance. When annual inspections are required, the computer connects to the Public Switched Telephone Network (PSTN) via a modem to call the on-site data acquisition terminals, inputting the data into the host computer's database for analysis and evaluation, thus determining whether the elevator is up to standard. To conserve telephone line resources, a small building complex (e.g., several buildings within 1 kilometer of each other) shares a single telephone line. Only data acquisition terminal #1 is connected to the telephone network. The remaining data acquisition terminals in the complex are connected to the 485 bus along with terminal #1, using software protocols to identify terminal numbers and communicate with the host computer. [align=center]Figure 1 System Composition Structure Diagram[/align] 3 Hardware Design of the Acquisition Terminal The elevator needs to monitor various information, such as leveling signals, car door locking, hall door locking, upper and lower limits, as well as running acceleration, temperature, and humidity signals. After signal processing or sensor circuit transformation, the final output to the acquisition terminal is standard digital or analog signals. Considering practical conditions and cost, an 8-bit MCU (microcontroller) with 16 digital inputs and 8 analog inputs can be used. The main technical data to be considered for the acquisition terminal include: acquisition cycle, communication protocol, communication rate, digital input acquisition, analog input acquisition, data storage capacity, etc. The hardware block diagram of the data acquisition terminal is shown in Figure 2. In Figure 2, a modem module is used to communicate with the remote host computer's MODEM through the telephone network. Its output is converted into standard RS485 level by a level conversion chip and then forms an RS485 network with other data acquisition terminals installed on nearby elevators. The latch is used to latch and acquire the input switch quantity. The A/D converter completes the acquisition of analog quantity. The clock chip provides a precise time reference for the entire system. It can generate real-time data such as year, month, day, hour, minute, second, and weekday. It also has a built-in lithium battery and clock circuit, and can operate independently without external power supply. The MCU expansion module is used to supplement the MCU's functions. It can add functions such as power-off protection and can also be used to expand the storage space so that a certain elevator can store up to 1 year of historical fault data. [align=center] Figure 2 Hardware block diagram of the data acquisition terminal[/align] [b]4 Software Design 4.1 Data Acquisition Software Design of the Data Acquisition Terminal[/b] The software of the data acquisition terminal is written in Visual Basic. The data acquisition part includes querying switch quantity and analog quantity, judging faults, and storing faults in a certain format. The software in this part operates on a timed polling method, with a polling interval of 1 second, meaning it polls 16 digital inputs and 8 analog inputs every second. If a fault is found in a certain input and meets the storage conditions, the fault number and time stamp of that input are stored in the E2PROM. The software flowchart for the data acquisition section is shown in Figure 3. [align=center] Figure 3 Data Acquisition Software Flowchart[/align] 4.2 Communication Software Design of the Acquisition Terminal The MODEM module of the acquisition terminal operates in called mode. When a call comes in, the software first identifies the caller ID. If it matches the pre-set remote management department's phone number, it sends an AT command to the host computer's MODEM to respond. At this point, the communication link between the two parties is successfully established. Data transmission can be simply viewed as communication between the MCU's serial port and the remote PC's serial port. The communication baud rate is 2400b/s, with no parity, 8 data bits, and 1 stop bit. Data transmission between the acquisition terminal and the remote host computer uses a command-response method, meaning that after the host computer sends a specific command, the acquisition terminal sends back the corresponding information. 4.3 Remote Host Management Computer Communication Software Design The remote host management computer is equipped with an external modem. When it needs to communicate with the lower-level acquisition terminal, it first sends a standard AT dialing command to the MO2DEM via the serial port. Once the other modem responds by picking up the phone, the communication between the two parties becomes standard serial communication. The host computer dialing program flowchart is shown in Figure 4. [align=center] Figure 4 Host Computer Dialing Program Flowchart[/align] The remote host computer software runs on Microsoft Windows XP operating system. The communication program is written in Microsoft VB 6.0 and utilizes the MSComm communication control. 4.4 Host Computer Evaluation and Management Software Design The host computer evaluation and management software is written in VB and mainly includes functional modules such as: administrator identity recognition, parameter setting for acquisition terminals, fault data entry, data analysis and evaluation, and report generation. SQL Server is used as the database management system to store and manage data, forming the backend database engine of the entire application system. VC uses ADO (ActiveX Data Object) to connect to the SQL Server database. The advantage of this approach is that VB can easily be used to develop front-end software, while SQL Server provides efficient database management. In the evaluation software, the annual fault records of a specific elevator entered into the database are first classified according to severity. Severe faults (such as the car door suddenly opening during operation) are classified as Class A, followed by Class B, Class C, and so on. Then, the number of faults in each class is statistically analyzed, resulting in a pie chart of each type of fault. If there are too many faults above Class B, the conclusion that the elevator is unqualified is printed directly, along with the reasons; if the number of faults is within acceptable limits, the conclusion that the elevator is qualified is printed. 5. Conclusion During elevator operation, the frequent starting and stopping of the drive motor and the switching of various relays create a very complex electromagnetic environment. Therefore, anti-interference is particularly important, especially since electromagnetic interference has a very strong impact on analog quantities, causing large signal jumps. Therefore, many anti-interference measures should be taken for the analog quantity acquisition part, such as adding filter circuits, adding shielding sleeves, and single-point grounding. The implementation of the elevator remote detection system greatly saves human and material resources and has high promotional value. References [1] Shen Yicheng. Modem User Guide [J]. Shaanxi Electronics Magazine, 2004, (17) [2] Ren Xia. Remote Communication Program Based on VB [J]. Computer Application, 2005, (5) [3] Wang Shichang. Computer System and Network Technology Development and Application Examples [M]. Beijing: Machinery Industry Press, 2003 First Author Introduction: Chen Feinan graduated from the School of Electrical Engineering, Xinjiang University, majoring in Control Theory and Control Engineering, with a Master of Engineering degree. He is currently employed at Xinjiang Uygur Autonomous Region Special Equipment Inspection Institute. Contact number: 13999852879 e-mail: [email protected] Mailing address: No. 9, Mianhua Street, Changjiang Road, Urumqi, Xinjiang Special Equipment Inspection Institute Postcode: 830000