At present, the monitoring of building equipment mostly depends on manual patrol inspection. For example, for some equipment requiring real-time monitoring, maintenance personnel are generally arranged to stay next to the equipment. Of course, the disadvantages of this model are also obvious. It not only consumes a lot of human resources, but also greatly increases the cost of monitoring. The current online equipment fault monitoring system mostly adopts the mode of acquisition card and PC. The acquisition card is responsible for collecting data, and PC is responsible for data processing and transmission. This system is bulky and expensive, so it is not suitable to be used in places with scattered production equipment and poor on-site working environment. In order to solve these problems, this paper applies the related technology of intelligent router and Internet technology to the design scheme of equipment monitoring system, so that the equipment fault detection system has the function of remote monitoring.
1. Principle of remote equipment monitoring system
The Internet-based remote equipment monitoring system designed in this paper is mainly composed of building equipment or industrial equipment, PLC control cabinet, intelligent router and remote server, as shown in Figure 1. Among them, building equipment can include air conditioning, lighting, etc. the main function of PLC control cabinet is to control the opening and closing of equipment. The function of remote server is to store the real-time monitoring information of equipment so that users can view it in real time through computer, tablet or mobile phone. Another function of server is when abnormal equipment data is detected, The alarm message can be pushed to the user terminal.
2. Design of intelligent router
This paper will use cortex-a8 embedded board to imitate the intelligent router. The software design of intelligent router mainly includes embedded Linux operating system, web server lighttpd, database mysql, MODBUS protocol and application program of monitoring equipment. The main hardware of intelligent router includes processor, 3G module, Ethernet port, serial port and SD card slot.
2.1 data acquisition
In this paper, MODBUS is used as the transmission protocol of real-time data, and serial port and Ethernet port are used as data acquisition methods. Finally, the data is transmitted to the server through Ethernet or 3G network, and the data is saved in the server database. All the data obtained from the device will be stored in the SD card of the intelligent router, and the data uploaded to the server only needs the key part. When you need to obtain all detailed data, you can also log in to the intelligent router remotely to view it. This can not only greatly reduce the data storage capacity of the server, but also greatly reduce the broadband traffic required by the client.
2.2 description of main software
Open wrt is an open source Linux distribution with good scalability and powerful network components. It is suitable for all kinds of embedded devices and routing devices. The file system of open wrt is writable, that is, users can add the functions they need without recompiling the whole system firmware. Lighttpd is an open source web server software, which is specially designed for high-performance websites. It has the characteristics of good performance, low memory overhead, rich modules and very low CPU utilization. Lighttpd is designed to provide a compatible, fast, secure and flexible web server environment for high-performance websites.
3. Software implementation of the system
3.1 add new equipment to be monitored
Each device to be monitored is uniquely determined by its own device name, device IP, device ID and device port. At the same time, the system will also generate a unique hash value for the device. In data monitoring, the system also stores the hash value as the unique identification of the device. The purpose of this is to modify the equipment information in the future without modifying too many data tables. In general, in order to better understand the operation status of a device, it is often not just one device point of the monitoring device, but multiple, and each monitored point may need different data monitoring speed due to the different sensitivity of its own data. In order to facilitate users to add new equipment and various information of equipment points and alarm points to be monitored, the system provides users with TFTP transmission mode, so that users can directly transmit monitoring files with specified format to the intelligent router. Users only need to fill in the relevant file name and TFTP server IP while adding a new device.
3.2 alarm handling
In order to be applicable to most of the monitored equipment, the monitoring system designed in this paper not only monitors the on and off switching values such as light bulbs, but also monitors the numerical values such as temperature and humidity. Compared with the numerical value, the monitoring of switching value will be relatively simple. The monitoring of numerical quantity is slightly more complex, because the value of numerical quantity is smooth, so its value may fluctuate in the alarm value under the condition of external interference. Eventually, the system will give an alarm sometimes and not. In order to solve the above problems, this paper sets a buffer for the alarm value of numerical quantity. When the status is no alarm, the alarm will be started only when the value of the numerical quantity is greater than the value of the alarm point. When the status is alarm, the alarm will be cancelled only when the value of the numerical quantity is smaller than the value of the alarm point. It mainly includes data acquisition program and alarm program. In addition, considering that the data may jitter due to external interference, the data value is processed only when it reaches the state transformation area and lasts for a certain time in the area.
This paper focuses on the basic principle of the system, and introduces the design of hardware circuit and system software of the main parts of the system in detail. Compared with traditional IT operation and maintenance services, it operation and maintenance services based on Internet have more advantages. With the deepening of Internet application field, intelligent router will be more widely used and developed. The remote monitoring system designed in this paper will also play a positive role.
Responsible editor: CT