1. Introduction Drawing is a crucial step in the textile process. The automatic control system of a drawing frame is primarily a standalone control system. Older models often employ a control structure of instruments and relays, resulting in poor system stability, significant human error, low yield, poor product quality, and high operating and maintenance costs. Even with advanced PLC control in some modern drawing frames, information exchange between the equipment and external systems remains difficult. This makes standalone automation systems typical "information silos." To improve the efficiency of the drawing process, we must utilize advanced automation and information technology to upgrade workshop equipment and management. Therefore, we use Profibus-DP fieldbus to construct a network for the drawing frame control system, offering advantages such as high openness, convenient wiring and installation, and low operating and maintenance costs. This also enhances the system's intelligence and automation, significantly improving the overall control level. 2. System Requirements A textile group company requested a technical upgrade of 34 drawing frames in its drawing frame workshop, adding self-adjusting and leveling functions to each machine and achieving centralized monitoring of the entire workshop's production schedule. The monitoring software running on the main computer in the central control room can display the production process diagram of the entire workshop, dynamically display the status and parameters of all equipment and instruments, and monitor the production process. It can also perform trend chart tracking of important parameters and system alarms. Through this system, the equipment on site can also be controlled and the relevant parameters can be modified, thereby realizing the centralized scheduling of the enterprise's production process. 3 System Design and Implementation According to the above requirements, when selecting the structure of the control network, we focused on studying the advantages and disadvantages of the currently popular DCS and FCS. We examined the feasibility of implementation, performance-price ratio, ease of maintenance, system scalability, and many other aspects. Finally, we selected FCS, based on Profibus, and used SIEMENS' S7-200 series PLC and WINCC configuration software to form a distributed monitoring network. 3.1 Profibus-DP Fieldbus Technology Profibus is an open fieldbus standard launched by SIEMENS. In 1989, it became the German standard DIN19245, in 1996, it became the European standard EN50170, and in December 1999, it was accepted as part of the international standard IEC61158[1]. Used for the bottom layer of the three-level network of factory automation system, namely workshop-level monitoring and field device layer data communication and control; used for distributed field controlled devices with communication interfaces, and systems with high requirements for data integration, remote diagnosis, fault alarm and digitization of the bottom layer devices. PROFIBUS follows the ISO/OSI model, and its communication model consists of three layers: physical layer, data link layer and application layer. PROFIBUS provides three protocol types: PROFIBUS-FMS, PROFIBUS-DP, and PROFIBUS-PA. In addition, for Siemens PLC systems, PROFIBUS provides two optimized communication methods: S7 communication and S5 compatible communication [2]. Among them, PROFIBUS-DP is a high-speed and economical device-level network, mainly used for communication between field controllers and distributed I/O, using the physical layer, data link layer and user interface, for high-speed data transmission of the field layer. The master station periodically reads the input information of the slave station and periodically sends the output information to the slave station. The bus cycle time must be shorter than the master station program cycle time. In addition, PROFIBUS-DP provides the non-periodic communication required by intelligent field devices for configuration, diagnostics, alarm processing, and determination of parameters for complex equipment during operation. 3.2 System Network Structure The system network structure designed by the author is shown in Figure 1. The network adopts a single master station system using PROFIBUS-DP, with an industrial computer configured with a CP5613 card as the host computer to monitor and manage the system; the CP5613 card acts as the master station, determining the bus transmission rate and assigning network addresses to each slave station; 34 S7-200 PLCs (CPU224) distributed across various work sites act as slave stations, responsible for collecting field information and sending relevant signals to the master station, as well as executing control commands. The S7-200 PLCs are connected to the CP5613 card via shielded twisted-pair cables using the DP port of the EM277 PROFIBUS-DP module, forming the entire PROFIBUS-DP fieldbus network. Another S7-200 PLC acts as a node in the control network (i.e., a DP slave station) controlling a drawing machine; its operating status does not affect the network or the operation of other nodes. Furthermore, it connects to the TP170 via its built-in RS-485 interface to control field devices. The TP170 communicates with the S7-200 PLC via PPI and does not participate in the PROFIBUS-DP bus network. Figure 1 System Network Structure Diagram 3.3 System Network Monitoring Design The S7-200 PLC programming of this control system uses Siemens' STEP7 MicroWIN4.0 software package. The host computer serves as the human-machine interface of the control system, and is equipped with Siemens' SIMATIC WINCC 6.0 configuration software. As the central monitoring computer, it monitors the status of the system, sets parameters, displays and records alarms, and provides complete data statistics and various analysis charts. The STEP7 MicroWIN4.0 software runs in the WINDOWS environment, with a user-friendly interface, convenient programming, and intuitive online debugging. The WINCC configuration software connects to the S7-200 PLC via a CP5613 card and an EM277 communication module using PROFIBUS-DP. (1) Configuration software performance: WINCC software is divided into four levels of management: project, screen, window and target; there is no limit to the number of projects, and each project can have up to 1000 screens; each screen can include up to 100 windows, 256 dynamic targets, 256 controllable targets, 16 historical operation charts, 16 current trend charts, and 16 alarm windows; it supports monitoring features such as tags, prescriptions, panels, and symbols; it supports 9 alarm types; and it allows for custom software scan cycles, with the shortest setting in this system being 50ms. (2) Profibus-DP connection between WINCC and S7-200: The Profibus-DP communication designed by the author is a master-slave communication mode. WINCC is the host computer monitoring software, and the host computer using WINCC can only act as the master station, so there can only be one host computer. Generally, using the Siemens CP5613 network integration card, a maximum of 8 S7-200 PLCs can be directly connected in PROFIBUS-DP network mode. This is because the monitoring software WINCC can only exchange data with the OPC Server through the OPC channel, and one OPC Server can only support 8 S7-200 PLCs. However, the monitoring system has a total of 34 PLCs. The author's solution to this problem is to build a network using the standard DP protocol. In this case, DP-5613 V6.2 software needs to be added to the original configuration. Also, when configuring the PC station, select "Application" instead of "OPC Server". In this way, the connection between WINCC and S7-200 PLC can be achieved through the method described below. (3) Install the GSD file (siem089.gsd) of EM277 into STEP 7-Micro/WIN. In STEP 7, click "Options" - "Install New GSD" to install the GSD file. After EM277 is installed, it can be found in the hardware directory “Profibus DP” – “Addition Field Devices” – “SIMATIC”. (4) Configure the network card Insert a PC STATION in the project, insert APPLICATUION in the first line, insert CP5613 in the fourth line (CP5613 is used as the DP master here), and establish a Profibus network. Add EM277 as a DP slave on the network. The process is shown in Figure 2. Configure the communication interface area as an 8-digit input area and an 8-digit output area, as shown in Figure 3. Double-click EM277 in Figure 2 and configure the address offset of EM277 to 5000. Figure 2 Establish Profibus network Figure 3 Configure communication interface area (5) After compiling and saving, configure PC STATION Click “Start Station Configuration” to enter the configuration screen. Click “Add” to add “Application”. It should be noted here that if the monitoring software added is "OPC Server", it will exchange data with OPC Server through the OPC channel, and one OPC Server can only support 8 S7-200 PLCs. Therefore, this step is very important. In addition, the network card mode is set in the same way as the hardware configuration, and the network card CP5613 is added in the fourth line. (6) Downloading the PC station In the control panel, open "Set PG/PC Interface" and set S7 ONLINE to "PC Internal" and access CP_L2_1 to "CP5613 (Profibus)". Then, by clicking "STATION NAME" of PC STATION, change the station name of PC STATION to be the same as the PC station name configured in STEP7. Download the configuration to PC STATION and confirm the status. (7) Set the address offset of DP slave in STEP 7-Micro/WIN, as shown in Figure 4. Figure 4 DP slave address offset setting Where: VW 5000 -> QW0 (Receiver buffer); IW0 -> V5008 (Sender buffer). (8) WINCC configuration. Open WINCC and add the Profibus-DP protocol in "tag management", as shown in Figure 5: [align=center][/align] Figure 5 WINCC configuration (9) Under the DP protocol, add a new connection and set the DP slave address. (10) Configure system parameters. Select CP5412 (A2) board 1, and select "system parameters" in the right-click menu to set the system parameters, as shown in Figure 6: Figure 6 Setting system parameters (11) Add the variable Tag and connect the input address, as shown in Figure 7: Figure 7 Adding the variable Tag In this way, the Profibus-DP connection between WINCC and S7-224PLC is completed. 3.4 System network monitoring implementation Based on the Profibus DP network, the network monitoring system of the workshop drawing machine is realized through WINCC system configuration. It can display the feeding speed, output speed, self-adjusting evenness rate and the historical trend of sliver evenness in the production process. It also alarms the main motor, servo motor, drum changer motor, fan, and various operating faults. Since the flowchart on the monitoring screen is drawn according to the production process, it can be clearly understood by the operators and also brings convenience to the maintenance personnel. The monitoring system can mainly realize the following functions: (1) Remote control function: Through simple operation on the host computer, the important parameters of each machine can be modified. (2) Real-time monitoring: Real-time display of the operating status of each drawing frame in the workshop, and at the same time, real-time display of production output status. (3) Real-time data acquisition and data analysis function: The host computer collects on-site data in real time, and displays the results on the monitoring screen after algorithm processing. In particular, it can display the trend chart of the sliver output by the left and right eyes of each drawing frame in real time. (4) Report generation function: It can automatically generate event reports and production reports, which is convenient for users to view data. (5) Printing function: It can print the sliver curve, event reports, and production reports of each drawing frame output, as well as other data and information that users care about. (6) Fault alarm function: It can immediately display the faults currently occurring in the drawing frame, and can also query historical fault information in the event report. (7) Emergency handling: If a serious dangerous fault occurs in the machine and there is no time to go to the workshop to handle it, the emergency stop button can be operated on the monitoring screen to stop the system to ensure the safety of important equipment and personnel. Some monitoring interfaces of this system are shown in Figure 8. Figure 8 Drawing Frame Network Monitoring System 4 Conclusion In summary, this system uses PROFIBUS-DP network technology to realize a distributed monitoring system, which greatly reduces the workload and cost of on-site signal connection, improves the accuracy and flexibility of signal transmission, reduces system cost, and brings convenience to installation, debugging and equipment maintenance. With the continuous development of modern information technology, computer technology and automation control technology, it is believed that the fieldbus technology based on PROFIBUS-DP will not only contribute to the improvement of production efficiency in this system, but also bring a broader prospect for the realization of centralized monitoring of production scheduling in multiple factories and the full integration and automation of the entire enterprise.