Abstract: The coal conveying system is an important system in a power plant, and the belt conveyor system is an important part of the coal conveying system. We utilize wireless fieldbus technology and wireless modules to simulate the coal conveying system, facilitating on-site commissioning and providing factual basis for further research on wireless fieldbus networks. Keywords: Wireless LAN; Fieldbus Network; Wireless Module Token 1 Introduction The coal conveying system is an important component of a power plant. Currently, China's coal conveying systems generally use PLC and DCS systems. The coal conveying system mainly consists of a series of equipment such as tipper feeder, bucket wheel conveyor, belt conveyor, coal plow, coal crusher, and iron separator. Among these, the belt conveyor system occupies a crucial position. Belt control can be divided into belt start-up, belt stop-up, belt misalignment alarm, interlocking of upper and lower belts, and current signal control of the belt motor. Belt conveyor system simulation is an important aspect of coal conveying system simulation. We must establish a model of the belt conveyor system. Using this model, we can simulate normal belt start-up and stop, and belt faults, thereby achieving simulation of the industrial site. The simulation system can then be used to simulate the industrial site and commission the coal conveying system. Currently, simulation systems are generally wired, which significantly limits their use for debugging coal conveying systems in different locations. Existing wireless control networks are mobile network systems built using wireless modules, enabling one-to-many or many-to-many communication. In industrial settings, many distributed control modules are needed. Wireless networks can effectively simulate coal conveying systems or other distributed systems. This project selected the reliable PTR8000 wireless module as the basic module for establishing the wireless network. The main purpose is to build a coal conveying simulation system, consisting of: a computer simulating the coal conveyor belt interface; an OPC server connected to a wireless transceiver module via a serial port; and the transceiver module enabling communication between the host simulator and the DCS system. Additionally, we will develop wireless modules with AI, AO, DI, and DO interfaces. The AI ​​and DI modules are wireless transmitters, and the AO and DO modules are wireless receivers, connecting to the AO, DO, AI, and DI modules in the DCS system, respectively. Using this system, we can effectively simulate conveyor belt systems and perform industrial site simulations. The entire system is shown in Figure 1. Figure 1 Coal Conveying Simulation System 2 Wireless Network 2.1 Wireless Local Area Network Technology and Standard Wireless networks, as an extension and supplement to wired networks, play an irreplaceable role in situations where the use of wired facilities is limited. Due to the openness of the ISM (industry/scientific/medical) frequency band, operators and users can freely use these frequency bands without application or authorization, thereby promoting the development of wireless data communication technology. Commonly used modulation methods for wireless digital transmission include narrowband digital modulation and spread spectrum modulation. Currently, spread spectrum modulation is the most common, mainly including direct sequence (DS) spread spectrum, frequency hopping (FH) spread spectrum, time hopping (TH) spread spectrum, linear frequency hopping spread spectrum, and their combinations. Wireless LANs emerged in the 1990s. With the rapid growth of the LAN market, various wireless LAN technologies and standards arose, including: (1) IEEE 802.11 and HiperLAN, typically used for wireless LAN applications; (2) the shared wireless access protocol (swap) proposed by the Home Radio Frequency Working Group (HRFWG), primarily for home applications; (3) the Bluetooth system proposed by the Bluetooth Special Interest Group (BSIG); (4) LMD (Local Multipoint Distribution Service) broadband fixed wireless access technology; and (5) Ultra-Wideband (UWB) wireless communication technology. The 802.11 standard is a wireless interconnection protocol introduced by the IEEE (Institute of Electrical and Electronics Engineers), including two variants: 802.11a and 802.11b, with 802.11b achieving a speed of 11 Mbps. The 802.11 standard enables interconnection of wireless products from various manufacturers. 2.2 Wireless Module (1) Introduction to the PTR8000 Module. The PTR8000 is a high-performance embedded wireless module specifically designed for point-to-multipoint wireless communication. It is a multi-channel, multi-band, low-power module. It has a built-in complete data communication protocol and CRC error detection. All wireless transmission and reception can be completed through SPI, with no garbled output. It is small in size, has a built-in loop antenna, stable performance and is not easily affected by external factors, and is not sensitive to power supply. Its maximum transmit power is +10dBm, with high anti-interference GFSK modulation, frequency hopping capability, unique carrier monitoring output, address matching output, and data ready output. Due to the above characteristics, this wireless module is suitable for use in industrial sites as a basic wireless module for industrial local area networks. (2) Introduction to Other Component Modules. Our designed module is a wireless module with DI (digital input), DO (digital output), AI (analog input), and AO (analog output) modules. It primarily utilizes the M68HC12 microcontroller as the core unit, with peripheral circuits implementing the DI, DO, AI, and AO functions for industrial environments. Considering the significant interference in industrial settings, we incorporated external anti-interference circuits, such as RC filters and opto-isolation circuits for the DI module. Using the M68HC12's SPI interface, we can easily achieve communication with the PTR8000 wireless module. Furthermore, for connection to a host computer, we designed a dedicated transceiver module based on the M68HC12. The DI transmitting module connects to the DO module on the DCS device. Its function is to acquire the digital signals transmitted by the DCS's DO module, process them, encode them, and then transmit them to the wireless transmitting module according to a specific protocol. The DO receiving module primarily connects to the DI module on the DCS device. Its function is to receive data from the wireless receiving module, decode it, and then transmit it in digital form to the AI ​​module on the DCS device. The AI ​​transmitting module primarily connects to the AO module on the DCS device. Its function is to acquire the analog signals transmitted by the AO module on the DCS device, process them, encode them, and then transmit them to the wireless transmitting module, which then sends them out according to a specific protocol. The AO receiving module primarily connects to the AI ​​module on the DCS device. Its function is to receive data from the wireless receiving module, decode it, and then transmit it in analog form to the AI ​​module on the DCS device. These five modules constitute the hardware wireless network portion of the entire simulation system, forming a wireless local area network. We can use many of these modules to implement a large coal conveying simulation system. 3 Wireless Network Software Implementation 3.1 Principle Design Since the high-speed signal processing part related to the RF protocol is embedded inside the module, the PTR8000 can be used with various low-cost microcontrollers, as well as high-speed processors such as DSPs. The PTR8000 provides an SPI interface, the rate of which is determined by the interface speed set by the microprocessor itself. In RX mode, the address match (AM) and data ready (DR) signals notify the MCU that a valid address and data packet have been received, and the microprocessor can then read the received data via SPI. In TX mode, the PTR8000 automatically generates a preamble and CRC checksum, and the data ready (DR) signal notifies the MCU that data transmission is complete. The PTR8000 has the following three modes: (1) Configuration programming: After power-on, the MCU first configures the PTR8000 module. First, set PWR, TXEN, and TRX_CE to configuration mode. The MCU moves the configuration data into the PTR8000 module through SPI. The configuration content is still valid after power-off and standby mode. The configuration data will only disappear when the power is removed. (2) Transmission mode: When the MCU has data to send to a specified node, the address of the receiving node (TX-address) and the valid data (TX-payload) are transmitted to the PTR8000 through the SPI interface. The application protocol or the interface speed is set by the MCU. The MCU sets TRX_CE and TX_EN to high to start the transmission. The PTR8000 internally processes the automatic power-on of the wireless system, the data packet completion (prefix and CRC check code), and the data packet transmission (100kbps, GFSK, Manchester encoding). If auto_retran is set high, ptr8000 will continuously send data packets until trx_ce is set low. When trx_ce is set low, ptr8000 ends data transmission and sets itself to standby mode. (3) Receive mode: RX mode is selected by setting trx_ce high and tx_en low. After 650us, ptr8000 monitors information in the air. When ptr8000 detects a carrier of the same frequency, carrier detection (CD) is set high. When ptr8000 receives a valid address, address matching (AM) is set high. When ptr8000 receives a valid data packet (CRC check is correct), ptr8000 removes the preamble, address and CRC bits, and data ready (DR) is set high. MCU sets trx_ce low, reception is complete, and enters standby mode. MCU can read valid data through the SPI interface at an appropriate rate. After all valid data is read, ptr8000 sets am and dr to low. 3.2 Wireless Network MCU Main Program In a wireless transmission network system, if the amount of information transmission is large and the task is full, the token method can be used. This propagation method has a better throughput than other methods. Its implementation principle is as follows: Once the network is established, a token is generated and transmitted on the network. When a station receives the token, it means that the station has the right to transmit information, and then transmits the information. After the transmission is completed, the token is sent to the next station. If the station has no information transmission, the token is sent directly to the next station. The next station obtains the token and transmits the information, and then sends the token to the next station. This continues until all stations have transmitted the information and then it returns to the beginning, repeating the process to achieve full network information transmission. To ensure reliable reception, the distance between any two stations in the ring must be limited, and hidden nodes must not appear when the ring is initially established. In the wireless ring network, the frame switching method is used. In the ring network mode, the following problems are mainly solved. (1) System initialization (token generation). The system initialization needs to solve the problem of token generation. After the wireless network is installed, each station is responsible for generating a token, but there is only one token in the entire network. The principle of generating a token is: sorted by address size, the station with the smallest address is most qualified to be the starting station of the token. (2) Establishment of logical ring. The station that has the token for the first time fills its own address into the "Request-Successor" frame, then sends the "Request-Successor" frame, and then listens for response frames on the channel. When each receiving station receives the "Request-Successor" frame, it fills the requester station address into the resource table in sorted by address size (duplicates are not filled), and then checks whether its own address is within the address range required by the requester. If not, it does not send a response frame. If it is, it sends the "Set-Successor" response frame. When the originating station receives the "Set-Successor" frame, it establishes or modifies the successor address in its own station and sends the token to the successor. When there are multiple response stations with "Set-Successor" frames, only the arbitration algorithm can determine the unique responder as the successor. After the successor receives the token, it solicits the successor again until there is no response. Then, it sends the token to the first station in the resource table as its successor station, thus initially establishing the logical ring. (3) Management of the logical ring. After the logical ring is established, there are still token maintenance, new station addition and old station exit transactions. These management are very complex and dynamic. They are divided into four parts: token transmission, normal operation process, new station addition to the logical ring, and exit from the logical ring. 4 Conclusion In the coal conveying simulation system, we used wireless fieldbus technology to decentralize the modules, which has mobility and can meet the needs of industrial sites. This has brought convenience to simulation debugging and also found certain factual basis for the realization of wireless fieldbus networks.