Currently, effectively controlling vehicle emissions has become an urgent task for environmental protection in China, necessitating the detection of vehicle exhaust pollutants during production. This article introduces an intelligent vehicle exhaust pollutant detection system that conforms to the EU-2 standard, based on an embedded Windows CE operating system and KingSCADA 6.0 configuration software, integrating operating condition simulation, sample gas acquisition, and sample gas analysis. I. System Overview The entire system consists of a central control unit, a chassis dynamometer, an exhaust gas sampling unit, an analytical instrument unit, and related auxiliary equipment. First, the chassis dynamometer simulates the vehicle's operating conditions. Then, the exhaust gas sampling system accurately and quantitatively collects the sample gas. Finally, the analytical instrument unit quantitatively detects the pollutant concentration in the sample gas. The central control unit automatically controls the entire system. The central control unit uses an embedded system as its core control unit. The system operator station is an industrial control computer running the Windows CE embedded operating system and KingSCADA 6.0 embedded version configuration software, responsible for issuing commands to the PLC, which acts as the field control and command execution element. Simultaneously, the industrial control computer communicates with the remote host PC using the TCP/IP protocol. The streamlined Windows CE embedded operating system enables the embedded version of KingSCADA 6.0 configuration software running on this operating system to achieve high execution efficiency, fully meeting the needs of on-site equipment operation. 1. Working Principle [align=center][img=400,315]http://www.e-works.net.cn/images/127936366695781250.GIF[/img] Figure 1 Schematic diagram of the vehicle exhaust gas detection system[/align] The overall system schematic diagram is shown in Figure 1. A car with its engine running simulates various driving conditions on a chassis dynamometer. The pollutants emitted from its exhaust gas pass through the ambient air filter under the action of a blower and enter the exhaust gas sampling system sampler for constant volume dilution sampling (CVS). The analytical instrument analyzes the sampled gas from the background gas bag and the diluted exhaust gas bag respectively, measuring the volume concentration of the pollutants. The emission values ​​of pollutants in automobile exhaust are calculated using the following formula: m_i = 1/S * V * d_i * c_i/10⁶ (i for HC, NOx, CO) Where: m_i – the mass of pollutants emitted; S – the distance traveled; V – the total volume of diluted exhaust gas under baseline conditions of 273K temperature and 101.33KPa atmospheric pressure, in m³; d_i – the volume of various pollutants at 273K temperature and 101.33KPa atmospheric pressure. Density at kPa; dCO = 1.25 kg/m³; dHC = 0.619 kg/m³; dNO₂ = 2.05 kg/m³ (NOx concentration in exhaust gas is expressed as NO₂ equivalent); ci — volumetric concentration of pollutants in diluted exhaust gas, 10⁻⁶. 2. Control System Operation Process: The industrial control computer acquires measurement data through sensors in the CVS system and analysis unit, converts it into digital signals conforming to the RS-485 standard through the data acquisition module, and transmits it to the touchscreen. The touchscreen transmits the measurement data to the PC (host computer) via TCP/IP protocol to complete data processing. Simultaneously, the touchscreen determines the current operating status based on the acquired signal values ​​and sends control commands to the analysis unit and the PLC of the CVS system. The PLC in the analysis unit mainly performs a series of gas path switching and range conversion operations for the analytical instruments. The PLC in the CVS system mainly performs process control of the CVS, realizing a series of functions such as automatic cleaning and sampling. After the control commands are processed by the PLC, they are converted into direct relay opening and closing signals to realize the task of opening and closing the CVS system solenoid valves and sampling pumps. In addition, the distribution box also provides a 380V power switch for the fan, which can manually control the start and stop of the fan. The control system structure block diagram is shown in Figure 2. [align=center][img=400,345]http://www.e-works.net.cn/images/127936366987343750.GIF[/img] Figure 2 Control System Structure Block Diagram[/align] II. System Hardware Composition To ensure the accuracy and reliability of the system, this paper selects the stable and reliable Windows CE embedded operating system in the industrial control field as the control core of the industrial control computer. The data acquisition module, PLC, relays and other components have stable performance, high acquisition and control accuracy, and fast response speed. 1. The industrial control computer (ICC) used as the operator station is a client application developed based on the embedded operating system Windows CE and the embedded configuration software KingSCADA 6.0 (128 points). The advantages of the Windows CE embedded system lie in its simple and efficient device management, support for different types of devices, support for plug-and-play management mode and energy-saving device control; and its real-time response capability for processing system input and output. KingSCADA Embedded Edition 6.0 provides a development platform based on an embedded operating system. Due to its high stability, low system resource consumption, and the fact that the configuration software itself provides drivers for a large number of common devices, resulting in a short development cycle, KingSCADA Embedded Edition 6.0 was chosen as the development tool. The hardware selected is the ADVANTECH-Advantech TPC064 touchscreen (embedded integrated industrial PC), whose main system parameters are as follows: LCD screen size: 5.7" TFT; CPU frequency: ARM9266MHz; Memory: 64M; CF card: 64M. The touchscreen's external data transmission interfaces mainly include four RS232 interfaces, two RS485 interfaces, one USB interface, and one 10/100M network interface. Using an industrial PC approach allows for multiple serial port inputs, resulting in fast processing speed and high efficiency. Furthermore, the touchscreen has a user-friendly interface, making operation simple and intuitive, meeting the real-time operation and display needs of the testing equipment. 2. PLC This paper selects the SIMATIC S7-200 series PLC. The main module communicates with the industrial PC via RS-232 serial port, and software programming is implemented using step7-Microwin. As a field device specifically designed for industrial production process control, the PLC features high reliability, strong adaptability, convenient communication and programming, and a modular structure. The PLC executes commands issued by the operator station and performs simple calculations such as alarm handling. The entire system has 24 hardware switching inputs controlled by the PLC. The analytical instrument unit has 5 three-way solenoid valves and one sampling pump, while the CVS unit has 7 two-way solenoid valves, 8 three-way solenoid valves, and three pumps. 3. Sensor and Data Acquisition Module: The analytical instrument unit outputs concentration values ​​as analog signals via the rear panel output terminals. The flow metering unit of the CVS unit outputs flow data as analog signals from sensors. Specific sensors include:

[＊] Standard long-bore nozzle flow meter: BYW-S-80, 4 m³/min ~ 8 m³/min, nozzle diameter 80mm, used for constant flow measurement in the main flow channel; [＊] Digital pressure transmitter: BYD-8, for pressure measurement at the front end of the standard long-bore nozzle flow meter, output signal 4 mA ~ 20mA DC, 24V; [＊] Capacitive differential pressure transmitter: 1151DP3E22M183, for pressure difference measurement at the front and rear ends of the standard long-bore nozzle flow meter, output signal 4-20mA DC, 24V; [＊] Explosion-proof digital temperature transmitter: BWD-8, for temperature measurement at the rear end of the standard long-bore nozzle flow meter, output signal 4 mA ~ 20mA DC, 24V, range 0～50℃; [＊] Pressure transmitter: CS20FUCIIIERC3Lm (3)A, used to control and protect the pressure of the sample gas sampling bag, output signal 4 mA～20mA DC, power supply range 15 V～28VDC. [＊] Data acquisition module: Advantech 16-channel A/D PCL-818 data acquisition card.

4. Communication module system communication methods are divided into two types: serial communication and TCP/IP protocol communication. The PLC and data acquisition module communicate with the industrial control computer via serial communication; the industrial control computer communicates with the PC via TCP/IP protocol. The hardware parameters are as follows: Industrial control computer network card: 1 10/100M network interface; PC network card - TP-LINK, 100M. III. System software design The programming of this embedded control system is divided into two parts: one is PLC software programming, which realizes the field control of the working unit; the other is the programming of the operator station touch screen. The touch screen judges the current working status based on the measurement data obtained by the sensor, and then sends the control instructions to the PLC of each unit, and generates an interactive human-machine interface. 1. PLC programming (1) Control flow description The PLC of the analysis instrument unit is responsible for the operation of gas path and range switching. The PLC of the CVS unit mainly performs process control of the CVS system to realize a series of functions such as automatic cleaning and automatic sampling. Taking the CVS system as an example, the PLC first controls the exhaust process of the CVS unit to empty the waste gas in the air bag; then controls the cleaning process to clean the pipeline; finally controls the automatic sampling to draw the background gas and dilution gas into the two air bags respectively, preparing for the gas analysis of the analyzer. The above process mainly includes the control of pump, valve switching and timing delay. The control process is shown in Figure 3. [align=center][img=400,485]http://www.e-works.net.cn/images/127936367611406250.GIF[/img] Figure 3 CVS system PLC control flowchart[/align] (2) Control program The entire control program is programmed using program code, which is more flexible, convenient and compact than ladder diagrams and functional modules. The main program module is as follows: LD SM0.1 // Initialization, call subroutine 0 CALL SBR_0 S M2.0, 4 // Set program execution flag LD M0.1 // Enable waiting program A M2.0 // Set M2.0 to 1 LPS LD M8.1 // Reset request ALD CALL SBR_I // Call subroutine 1 // SBR_0: LD SM0.0 …． ． // Initialize pump and valve status CRET, SBR_I: LD SM0.0 LD M3.0 …． ． // Control CVS workflow CRET 2. Touchscreen control program design The operator station in the system uses a touchscreen to realize interactive human-machine dialogue. It includes 5 main interfaces: system main interface, CVS interface, analytical instrument interface, report and historical data query and printing interface, and manual interface. The design uses buttons to control the PLC operation in a simple and intuitive way, with functions such as displaying operation status and data, fault alarm, and report query. IV. Conclusion The entire system fully meets the requirements of automobile manufacturers for on-site monitoring of vehicle exhaust pollutant content. Through a simple and intuitive human-machine interface, complex operations can be performed, overcoming the shortcomings of previous monitoring systems such as low reliability, high failure rate, and low operational efficiency, thereby effectively improving the production management level of automobile manufacturers in China.