Elevator manufacturers' monitoring systems are all independently developed and can only be used on their own products, and are expensive. Furthermore, with the continuous innovation of elevator technology, the obsolescence rate of its drive and control technologies is also accelerating. Many older elevator models face technical upgrades, with common upgrade methods replacing voltage regulation and pole-changing speed regulation with frequency conversion speed regulation, and upgrading relay control systems. These factors provide more space for control components used in elevator monitoring systems, making elevator-based monitoring systems particularly suitable for elevators undergoing upgrades. 1. Elevator Monitoring System An elevator monitoring system is required to both monitor elevator status and perform daily management. Functionally, it can be divided into: elevator status during faults; data summary for each work cycle; and daily management information. A large amount of information needs to be monitored during elevator operation, roughly categorized as: door opening limit switch, door closing limit switch, safety contact plate, light curtain protection, hall door lock circuit, car door lock circuit; safety circuit, emergency stop circuit, limit switch status; drive information, call information, location information, brake status; running time, number of calls, annual inspection time, maintenance history, etc. Monitoring the elevator can provide a clear overview of faults. As we all know, the door system is a component of elevators that is prone to failure. Before an elevator stops, there are always some minor faults that occur frequently, but these minor faults are often overlooked because they do not cause the elevator to stop operating.
Taking improper adjustment of the gap between the hall door lock and the door knife as an example, under uneven load conditions, the door knife may collide with the door opening wheel, causing the elevator to stop suddenly. However, due to the elevator's self-correction function, the elevator will automatically return to normal within a few minutes. "This type of fault is highly random and often goes unnoticed, especially in automatically running elevators. However, as small faults accumulate, they will eventually lead to major faults or even accidents. The monitoring system will not miss these faults and can even locate the floor where the fault occurs, thus saving maintenance personnel time in finding the fault point." When a fault occurs, the collection of various information will help in fault diagnosis and accident prevention. "With targeted settings, all necessary information can be collected. For the statistical content required by management personnel, the monitoring system can summarize different data in categories."
For example, determining the operating status of an elevator is mainly done through the failure rate. However, the failure rate is often calculated by the number of failures within a certain operating cycle. The number of operations and operating time of elevators in different buildings and for different purposes vary greatly, making it difficult to use this failure rate as a basis for measuring the elevator's operating status. Instead, measuring the number of failures within the operating time or number of operations allows for accurate determination of the operating status. "A monitoring system can accurately collect and record elevator operating time, number of operations, and other operational data, making this problem much easier to solve. Daily management information includes annual inspection time, maintenance costs, and parts usage." This information is very easy to collect and transmit in a system based on control units; some of it consists of digital/on/off signals, while others are internal variables used by the control program for calculation and comparison.
By simply adding specific modules, the network function can be used to complete the collection and transmission of on-site data. 2. Introduction to PLC Networking Function: It has strong networking capabilities. Taking the 1 series as an example, it can form multiple network structures through adapter cards and intelligent modules, providing RS232/RS422 and other interface forms. It can form multi-level networks, with a maximum of 100 connected units. It uses transmission media such as twisted-pair cables, coaxial cables, and fiber optic cables to connect and exchange information with the host computer via computer adapter cards, modules, or modules themselves. Simultaneously, it can also use modules to form hierarchical networks, providing a flexible networking method and a technical foundation for forming multi-elevator monitoring systems. 3. There are two types of elevator monitoring systems based on PLC: one is the control system designed by the manufacturer; the other is for retrofitted elevators. The first type of control system often uses a board structure with many seven-segment LED displays or a matrix display system. In order not to affect the safety performance of the original control system, the information displayed on the board needs to be converted into usable variables using photoelectric components. Then, the variables are assigned values according to the content represented by the information. The second type of monitoring is used. For the second type, products with network functionality are directly selected as the control unit of the system, such as the C200H series products from OMRON. These products are used as control elements and their network functionality is used to transmit data to the monitoring system. However, the latter type is rarely developed and utilized, resulting in a great waste of resources.
The monitoring system based on this is constructed as follows: (1) Select a suitable network form according to the number and location of elevators and the conditions available to the owners, and then form a network. (2) When necessary, program the necessary procedures (programming is not required under some network forms) and store the monitored and collected data in a designated area for access by the host computer and others. (3) Monitor faults in real time, with elevator faults as the interrupt source. When faults such as door lock circuit unexpectedly disconnected, door timeout, various limit switches abnormal, various protection switches abnormal, safety and emergency stop circuit disconnected, drive status abnormal, position information error, and brake abnormal occur, the faulty elevator issues an interrupt request. After the host computer responds, it collects fault information, and the host computer's monitoring system makes a corresponding fault report. Then, it automatically dispatches personnel for maintenance according to the pre-set program. (4) For general work information such as running time and number of times, transmit it to the host computer at fixed times (network idle time). (5) On the host computer, develop the main control program and use configuration software to simulate the elevator operation status, and prominently display the fault type and fault point. Create a database to complete the statistical analysis, report generation, and printing of work information and faults.
