Application of DataSocket Technology in Networked On-line Particle Measuring Instrument

1 Principle of particle measuring instrument

The stand-alone particle measuring instrument has been successfully developed in the author's laboratory and applied in production. The instrument adopts the measurement principle of total light scattering method, as shown in Figure 1.

In the figure, I0 is the incident light intensity, and I is the transmitted light intensity.

The principle of the total scattering method is based on the Beer-Lambert theorem. In Figure 1, if a beam of parallel monochromatic light with an intensity of I0 and a wavelength of λ is incident on a medium containing particles to be measured, the intensity of the light will decay due to the scattering and absorption of the particles:

Where τ is the turbidity of the medium

Assuming that the spatial distribution of the particle group in the medium is disordered and uniform, that is, the turbidity τ is independent of the optical path L, integrate equation (1) along the entire optical path

Formula (3) describes the attenuation law of light in a granular medium.

In this system, when a white light beam passes through a medium containing particles, the intensity of the transmitted light after passing through the medium is attenuated due to scattering and absorption by the particles. The degree of attenuation is related to the size and number (concentration) of the particles, which provides a scale for particle measurement. In addition, in addition to the particle size, the total scattering method can also measure the concentration of particles at the same time, which is a prominent feature of this method.

2 About DataSocket Technology

DataSocket consists of two parts: DataSocket API and DataSocket Server.

DataSocket API: It is an application interface that is independent of protocols, programming languages, and operating systems. It is implemented through ActiveX controls and supports multiple data types, including strings, scalars, Boolean variables, and waveforms. It automatically converts the user's measured data into a byte stream transmitted on the network and is suitable for any programming environment.

DataSocket Server: It is a small, independently running program that uses the DSTP (DataSocket Transfer Protocol) protocol to communicate and exchange data between two applications. DataSocket Server has the function of broadcasting field measurement results on the Internet at high speed, simplifying TCP programming. After configuring DataSocket Server on the server side, when DataSocket Server is run on the client side, the program based on the TCP network connection of the Internet can be accessed.

From the perspective of data sharing, DataSocket follows the TCP/IP protocol and is an advanced encapsulation of WinSock. DataSocket greatly simplifies the transmission of real-time data, making it as convenient to transmit test data through the network as to write information to a file. Therefore, it has the advantages of easy use, less programming workload, and no need to understand the underlying operation process. It is particularly suitable for the development of applications such as remote data acquisition, monitoring and data sharing. With it, data can be shared between different applications and data sources, and field data can be easily shared and published in the measurement control system, and published in real time on the Internet.

3 The composition and implementation of the networked online measuring instrument system

The online particle measuring instrument adopts DataSocket technology. Since DataSocket is suitable for the transmission of broadcast data and high-speed data, the network measurement and control of the online measurement system can achieve the effect of real-time data transmission, and the reliability of the system has been significantly improved. The DataSocket API interface provided by it is applicable to programming environments such as VB and VC. The monitoring system of this measuring instrument calls DataSocket in the VB environment; the database background uses SQL SERVER 7.0; and the information publishing function of IIS is used to display various curves and bar lines. The system structure of the online measuring instrument is shown in Figure 2. [page]

In Figure 2, a white light source irradiates a particle group. Due to the scattering and absorption of the particle group, the intensity-attenuated transmitted light is emitted from the particle group and enters the spectroscopic system, dispersing the white light into light of different wavelengths, which is then synchronously detected by the photoelectric detection array. The obtained electrical signal is amplified and A/D converted to send the data to the computer (WebServer) for data processing. The data is uploaded using DataSocket. Because DataSocket can access local files and data on HTTP and FTP servers, and provides a consistent API for the bottom layer, programmers do not need to write specific program codes for different data formats and communication protocols. It uses a method similar to the same resource locator (URL) in the Web to locate the data source. Different prefixes of the URL represent different data types and provide a way for the machine to establish a connection. File represents a local file, http is a hypertext transfer resource, ftp is a file transfer protocol, and dstp represents real-time data from a DataSocket server. Since the DataSocket protocol has been encapsulated in NI's Component Works as an ActiveX control for developers to use, developers can use ActiveX controls and Web page development tools to publish to users in the form of web pages through the Internet/Intranet. Users can enter the IP address of the computer to be monitored in the Web page to activate data collection and display on the Web page, thereby realizing remote monitoring of the system and real-time data collection.

On the server, there are mainly two types of programs. One is to divide the transmitted data into several fields and put them into SQL Server as a real-time database for the networked online particle measuring instrument. The database development language uses PowerBuilder, and the database background uses SQL Server 7.0, mainly to facilitate customers to record historical data and remotely query, record and print data. The other type is IIS application. The Web server uses IIS to publish information and provide online monitoring services to remote customers through the network.

In this way, the online particle measuring instrument uses DataSocket to form a remote intelligent test node, run applications on the node to complete data collection, data analysis and other tasks, and use the functions provided by DataSocket to send test data back to the local PC node through the network.

4 Conclusion

Since the online particle measuring instrument uses DataSocket technology for data transmission, the transmission of redundant data is effectively reduced. This B/S structured remote monitoring system is very convenient to use. The monitoring end can be anywhere connected to the Internet, which can well meet the requirements for timely sharing of test data. At the same time, this solution also provides a reference model for enterprises to conduct online measurements based on the network.

References
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[4] Wang Naining, et al. Optical measurement technology and application of particle size [M]. Beijing: Atomic Energy Press, 2000.