Research on remote monitoring system of dust emission based on LabVIEW

At present, the overall deterioration trend of my country's ecological environment has not been fundamentally reversed, and the environmental pollution situation is becoming increasingly serious. Coal smoke pollution represented by dust and SO2 is a common problem of air pollution in my country. Among them, dust emitted from chimneys to the atmosphere is one of the main pollution, which causes great harm to human health. Therefore, the necessity of dust emission monitoring has been increasingly recognized by the society, and the instruments related to such environmental monitoring are also being continuously improved. However, there are still problems such as long feedback time of monitoring data, which is not conducive to guiding production; it is inconvenient to conduct long-term on-site monitoring for some dangerous, harsh environments, and monitoring stations that are not suitable for personnel operation; the transmission process of measurement data is too complicated. In view of the above problems, the remote monitoring system of dust emission is built on the LabVIEW 8.O software platform using virtual instrument technology and network communication technology, using the communication function module in LabVIEW, and graphical programming language.

1 Implementation of Virtual Instrument Remote Monitoring
LabVIEW is a virtual software development tool based on a graphical programming language. DataSocket is a network transmission technology provided by NI. It is based on the TCP/IP protocol, but does not require complex underlying TCP programming. It can only transmit field measurement data to multiple remote terminals simultaneously through a computer network. It greatly simplifies the data transmission process between applications and between computers. Therefore, it is quite convenient for users to use DataSocket technology to transmit data. Whether through programming methods or front panel object link methods, using DataSocket technology, computers can transmit data to each other through the Internet after the LabVIEW program is running.

2 Application of DataSocket Technology in Remote Monitoring of Dust Emissions
The laboratory has successfully developed a laser particle size analyzer system. The system uses an SSPA detector to detect the scattered light signal after the laser passes through the simulated chimney. At the same time, the data acquisition card M6220 provided by NI is used to collect the scattered light signal, and then the data is processed to reflect the status of chimney dust emissions. All these work is done on the LabVIEW 8.0 software platform. Of course, this simulation system will eventually be installed in the chimney of the factory to realize the function of monitoring dust emissions, which also involves the issue of remote monitoring. By comparing several solutions, in view of the powerful function of DataSocket network transmission technology in LabVIEW and its simple operation characteristics, this solution is used to monitor the status of chimney dust emissions in real time online.
There are two ways to transmit data using DataSocket, one is to transmit data between front panel controls; the other is to transmit data in the program. These two methods were used in the laboratory for experiments.
The first is to use DataSocket to link front panel objects. First, you must use Lab-VIEW 8.0 to write the acquisition program on the computer that performs the signal acquisition task on site, and then make some necessary settings on the object properties to be linked on the front panel of the program to achieve the link. The settings include the link mode, link type and link position. Figure 1 shows the front panel program for on-site dust emission data acquisition. The front panel objects include sampling channels, sampling rates, sampling points, signal display, start and stop buttons, and storage buttons. These objects are placed on the front panel of another computer next to the acquisition site. However, there is no need to connect the objects here. You only need to make corresponding settings on the properties of the objects to achieve remote control of the on-site acquisition program. Figure 2 shows the front panel program for users to remotely monitor the acquisition of dust emission sample data. Remote users can control the on-site data acquisition process through the controls in the front panel program shown in Figure 2, and changes in the on-site acquisition method and data will also be fed back to the remote user end. For example, if there is a computer collecting data at the dust emission site, then the remote user can control the data acquisition program through another computer, modify its sampling channel and sampling times, and read its sampling data. The result interface of the data processing on site can also be transmitted to the remote user end, or the data can be processed at the remote user end to finally obtain the dust emission status.

The second method is to use programming to establish a link. You can use the DataSocket write and DataSocket Read functions in the function sub-template to write a program. First, use DataSocket write to write data on a computer at the collection site. This computer must open DataSocket Serve before running the program. Then write a program on another computer to call the DataSocket Read function to read data from the location specified by the URL (that is, the address of the computer collecting data on site). When using this method to transmit data, DataSocket Serve only publishes the latest data to the data client. When the computer that publishes data runs faster than the computer that receives data, some data will be overwritten before being read, which will cause data loss. In order to ensure the accuracy of transmitted data, the data buffer method should be used to transmit data. In the process of writing this program, the DataSocket Select URL function, DataSocket Open function, DataSocket Read function and DataSocket Close function in the DataSocket module are used. Figures 3 and 4 are the flowcharts of writing the data collected on site to DataSock-et and reading the data on site using the buffer method. After the program in Figure 4 is run, a dialog box will pop up to prompt the user to select a data source and output the URL selected by the user. In this way, the link between the computer collecting data on site and the remote computer is established. [page]

In addition, programs can also be published on the Web. Using LabVIEW's Web server, you can publish the front panel image of the LabVIEW program on the network so that it can be browsed by remote computers with permission. After opening and setting up the Web server in LabVIEW on the computer that publishes the program, the computers on the network, regardless of whether LabVIEW is installed or not, can dynamically view the front panel of the program in the memory of the computer where the Web server is located by entering the correct URL in the Web browser in the specified format. Figure 5 shows a web page of a computer on the network using a Web browser to view the front panel of the program when monitoring dust emissions on site.

In practical applications, a combination of the above methods can be used to establish a remote monitoring system for dust emissions. The envisioned atmospheric environment monitoring system is mainly composed of on-site monitoring stations, data information centers, government environmental protection departments, Guangzhou Environmental Science Institute and other units, which are connected through the Internet to realize a network information platform for establishing an environmental information database, sharing environmental monitoring data, and exchanging relevant information. Figure 6 shows the network block diagram of the atmospheric environment information system.

3 Conclusion
Remote monitoring of dust emission is of great significance. The DataSocket technology of Lab-VIEW 8.0 provides a convenient implementation method for remote monitoring. Through the network, the environmental protection department can remotely monitor multiple environmental monitoring points, and can get feedback information from each monitoring point in real time. In addition, data can be exchanged between each monitoring station, which greatly improves the efficiency of environmental monitoring. This dust emission remote monitoring system has successfully completed the simulation experiment in the laboratory and obtained relatively accurate measurement data. It is believed that its application will play a positive role in environmental protection.