Abstract: This paper introduces a PC104-based data acquisition instrument and elaborates on the design concept and specific implementation of the system's hardware and software. It also presents the design idea of ​​a data analysis system software suitable for this data acquisition instrument. This system is an automated device with real-time on-site data acquisition and processing capabilities. Keywords: PC104 bus, data acquisition, data analysis [align=center]Data Acquisition Instrument and Data Analysis System Based on PC104 Bus[/align] Abstract: This paper introduces a data acquisition instrument based on PC104 bus. The hardware block diagram and software flowcharts of the system are given. It elaborates the design thinking and specific implementation of the system. The design thinking of a data analysis system adapted for this data acquisition instrument is also explained. This system is an automatic device with field real-time data acquisition and processing functions. Key words: data acquisition; data analysis; PC104 bus 1 Introduction In recent years, with the rapid development of communication technology and the widespread application of data acquisition systems, people have put forward increasingly higher requirements for the main technical indicators of data acquisition, such as sampling rate, resolution, accuracy, control method, and anti-interference capability. Especially for embedded computer data acquisition systems used in industrial settings, the complexity and diversity of industrial environments place higher demands on the hardware and software design: miniaturization and portability, high resistance to vibration and shock, good compatibility and heat dissipation, high reliability and maintainability, etc. Our designed PC104 bus-based data acquisition and analysis system is an automated device with real-time data acquisition and processing capabilities. It features real-time acquisition, automatic storage, instant display, instant feedback, and automatic transmission, ensuring the authenticity, validity, timeliness, and availability of field data. The use of this system will change the time-consuming, labor-intensive, and error-prone manual recording problems in manufacturing process quality data inspection. Managers can directly perform process capability analysis and control chart analysis on the acquired data through the data analysis system, achieving process quality assurance. 2. Hardware Integration Design The hardware integration design of the PC104 bus data acquisition instrument mainly includes the integrated connection of the PC104 bus motherboard and the PC104 data acquisition card, as well as the connection of other interface devices on the motherboard. The PC104 bus system adopts a compact stacking installation method. The data acquisition card and motherboard are stacked, which is beneficial for designing high-density, small-size portable data acquisition instruments. The structure of the PC104 bus data acquisition instrument is shown in Figure 1. [align=center] Figure 1 Data Acquisition Instrument Structure Diagram[/align] 2.1 Motherboard The motherboard of the data acquisition instrument adopts a standard PC104 structure with a low-power 300MHz processor. The PC104 motherboard has a small and compact structure, uses all CMOS devices, resulting in lower overall power consumption. It is an ideal solution for developing field instruments that work in harsh environments using the PC104 as the working platform. 2.2 Data Acquisition Card The acquisition card adopts a PC104 data acquisition card, which can form a high-performance data acquisition and control system with the PC/104 CPU module system. It has a compact structure and is suitable for embedded and portable applications. 3 Data Acquisition Software Design The PC104 data acquisition system uses the Windows operating system and is developed and programmed using the C++ language. The flowchart of the data acquisition system is shown in Figure 2. [align=center] Figure 2 Data Acquisition Program Flowchart[/align] The development and application of measurement and control systems under the Windows environment has become a trend due to its multi-tasking operation and user-friendly interface. Meanwhile, the C++ language, with its powerful functions and ease of use, has also been widely used in measurement and control system development. Therefore, in order to better expand the functions of the data acquisition instrument and provide users with a good user interface, we chose the Windows operating system and used the C++ language for programming. The dynamic link library (DLL) includes various C/C++ functions for data acquisition operations. These functions are called under the C++ Builder development platform to realize the setup, sampling, and data processing of the data acquisition system. Data is stored in two ways: database and text file format. C++ Builder has powerful database functions, providing convenience for the storage and processing of large amounts of data. Text format data storage is used to achieve fast and timely data processing. 4 Data Analysis Software Design When the system correctly acquires data, it may not be able to correctly determine whether the product manufacturing process meets engineering standards or technical specifications. This data analysis software ensures process quality by monitoring the process capability index of the product manufacturing process and displaying the controlled state of the process using control charts. The software design concept is shown in Figure 3. [align=center]Figure 3 Data Acquisition Instrument[/align] Data query involves selecting the data to be processed as needed, and can be divided into two formats: database query and text format data query. Data initialization, i.e., data grouping processing, includes cases where the sampled data is not grouped, the sampled data comes from an Xbar-S control chart, and the sampled data comes from an Xbar-R control chart. Based on these three different cases, the mean μ, range R, standard deviation s, and process standardization offset δ of the data are calculated respectively. The process capability index calculation includes the calculation of the process capability index Cp when the specification center M coincides with the controlled process center (i.e., the normal mean) μ. The process capability index Cpk considers the positional relationship between the mean of the process characteristic value and the tolerance zone. To ensure process alignment and reduce quality losses, the process capability index Cpm was proposed to meet this requirement. The control chart section displays the control status of the process, including Xbar-S and Xbar-R control charts. Based on the collected data, graphical indicators are used to determine whether the production process is under control, facilitating effective production adjustments. 5. Experimental Example A workshop processes a batch of pistons. The following is a portion of the data collected regarding the piston outer diameter when monitoring actual production using this system. The piston diameter design requirement is a target value of Tg = 74.002; the specification upper limit USL and specification lower limit LSL are USL = 74.030 and LSL = 73.960, respectively. The table below shows 20 sample data collected on-site, with a sample size of 5. The sample data are as follows: Table 1 Diameter-related data (unit: mm) From the table, we can obtain: 5.1 Calculate the process capability index of this group of data: The estimated values ​​of the process standard deviation and process mean of the whole batch of samples are: The upper limit of specification (USL) and the lower limit of specification (LSL) are: USL=74.030, LSL=73.960 According to the formula, the process capability indices are: Cp =1.21, Cpk =1.01, Cpm =1.04 5.2 Calculate the control limits in the sample conventional control chart: From n=5, look up the relevant table of conventional control charts. The coefficients A2 = 0.577, D4 = 2.115, D3 = 0. The upper and lower control limits of the chart are: The upper and lower control limits of the R chart are: Thus, the control chart is obtained, as shown in Figure 4. [align=center] Figure 4 Control Chart[/align] 5.3 Calculate the control limits in the sample conventional control chart: From n=5, look up the relevant table of conventional control charts, The coefficients are used to obtain the control chart, as shown in Figure 5. [align=center] Figure 5 Control Chart[/align] The mean-range control chart (Figure 5) is mainly used to monitor whether the mean of the production process is at or maintained at the required level. The function of the figure is similar to that of the figure, except that the standard deviation s is used instead of the range R. Since the standard deviation s is more accurate than the range R, the s control chart is more effective than the R control chart, especially when the sample size is relatively large. By observing the control chart above, it can be seen that the data are distributed between the upper and lower control limits of the conventional control chart, without any tendency of "chain", "deviation", or "cycle". Therefore, it is determined that the quality characteristic value of the diameter of this batch of parts has not fluctuated abnormally during the production process, and the production process of the product is under control. 5 Conclusion The data acquisition instrument and data analysis system based on the PC104 bus designed above have high compatibility, compact structure, small size and low power consumption, and are particularly suitable for industrial field measurement and control equipment with high requirements for size and function. This system was designed with a comprehensive consideration of ease of use, reliable operation, and good real-time performance. In tests conducted in complex and diverse industrial environments, the hardware and software design of this data acquisition system met the higher requirements of customers, highlighting its advantages of small size, portability, and high reliability. Therefore, it has broad market application prospects. 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