Research And Development Of Control System For Atomic Fluorescence Spectrometer Based On PDA

Atomic fluorescence spectrometer has been widely used in Environmental protection, water quality monitoring, food hygiene, disease control, and other fields in our country, and it has become a national standard method of heavy metals detection in the disease control, food safety, drinking water and mineral water fields. However, as the instrument relies on the traditional desktop computer control mode through serial port, it has the deficiency of poor mobility and hard wiring in the place where scene environment is complex. For this reason, take advantage of portable mobile control technology and wireless communication technology to control the equipment, gives full play to the advantage of the mobility of PDA and the wireless communication of Bluetooth, creates a work pattern of controlling and accessing information of equipment anytime and anywhere, gives full play to the advantage of the people's intelligence and intelligent equipments working together. The main task of this paper is to design and implement the top software control system on the PDA using the wireless communication of Bluetooth for AFS-3100 atomic fluorescence spectrometer, a production of the BEIJING KECHUANG HAIGUANG INSTRUMENT Co., Ltd.This paper based on. Net Compact Framework technology, designed and implemented the control system running on the Windows Mobile operating system for AFS-3100 atomic fluorescence spectrometer, successfully transplanted the main functions of the instrument's control system from desktop to the PDA. The system mainly consists of three parts: the establishment of Bluetooth connectivity between PDA and AFS-3100, the control procedures of the instrument on PDA, and data processing.1,The control system uses the Bluetooth manager which the operation system includes to search and connect Bluetooth devices, takes advantages of the SerialPort operation class offered by .Net Compact Framework to control the Bluetooth virtual serial port in the virtual serial environment built by the RFCOMM serial simulation protocol in the Bluetooth protocol stacks, so as to complete the wireless control based on Bluetooth virtual serial port. .Net Compact Framework is the subset of .Net Framework full-featured version, inherits .NET Framework's common language runtime architecture for running managed code, provides the interoperability of application procedures and personal mobile devices (Windows CE operating system). .Net Compact Framework offers multiple methods of the Read and Write method supported by the SerialPort class to read and send data in the buffer. Use the control system of AFS-3100 to send parameters,detect samples and control operations must comply with the communication protocol of the instrument, this paper uses the query method to receive the data of AFS-3100 so as to resolve the data losing phenomenon may be happened incidentally in the event driven method.2,The control procedures of the instrument on PDA is the operating and management area of the whole instrument control system. It is in charge of equipment performance testing, measurement conditions settings, measurement process control and displaying and preserving the measurement results. The whole process are all based on the SerialPort class offered by .Net Compact Framework to implement the parameters sending and data receiving through virtual serial port. According to the PC control system of AFS-3100, designed and implemented the PDA control system of the instrument, complied the transplant of the control system successfully. Among the function modules, the linking communication module takes charge of the Bluetooth connectivity between PDA and AFS-3100; the equipment self-inspection module contains gas circuit self-inspection, intermittent flow circuit system self-inspection and automatic sampler self-inspection; the instrument work conditions settings takes charge of setting the instrument conditions, measurement conditions, intermittent flow procedure conditions, automatic sampler parameter and standard sample parameters of A/B channel, it is the necessary part to operate the instrument; the measurement of standard blank and sample black, drawing standard curve and the measurement of sample implement the control of AFS-3100. The storage and call of data uses the SaveFileDialog class and OpenFileDialog class provided by .Net Framework. The control system uses a fixed text format to preserve the measurement results every time. User selects the relevant file and call it will open the file and display the data in the right place.3,Atomic fluorescence spectroscopy method belongs to relative measurement method, needs to identify the quantitative relationship equation between the density of tested element and the fluorescence signal intensity detected by the instrument. Based on the known equation, according to the magnitude of the fluorescence signal intensity from the sample detected by the instrument, the data processing module will calculate the density of the element in the sample. In the practical work, generally uses the regression analysis method to process the initial data provided by AFS-3100, then sets up the regression equation between the density of tested element and the fluorescence signal intensity, and at last obtain the quantitative relationship equation. In the process of a certain measurement the control system processes the initial data returned from the instrument in real-time, then draws the simulation monitoring curve; when this measurement finishes, it will calculate the result of the sample measurement based on the standard curve drew by an order linear regression algorithm or second-order non-linear regression algorithm. The precision algorithm and the detection limit algorithm of the instrument are relational with the performance of the instrument. They separately represent the detection ability and the stability of the instrument, are important technical parameters of Atomic fluorescence spectrometer.The control system referred to in this paper is applying and testing in the BEIJING KECHUANG HAIGUANG INSTRUMENT Co., Ltd. The system's inadequacy includes the following points: depends on the Bluetooth manager which the operation system includes to search and connect with the instrument's Bluetooth module, user should build up the Bluetooth connection themselves before using the system. In addition, the resource of the PDA is limited; repeatedly use of the controls influence the start-up time of the system; and how to display the data much reasonable on the showing forms are all needed to be improved in future work.