Abstract : This paper discusses the application of PROFIBUS-DP fieldbus in logistics conveyor belt control. Based on the actual needs of the logistics monitoring system, the hardware and software design of the monitoring system were completed, realizing PLC control of conveyor belt movement, acquisition of material barcode, color, weight, shape and size data, and warehouse storage and retrieval of materials. Keywords : PROFIBUS-DP; PLC; Logistics conveyor belt Classification number: TP336 Document code: B [align=center]The Design of Transmission Belt's Harmonious Control Based on PROFIBUS CHEN guojian , XIE guanghan (Institute of Automation, Guangdong University of Technology, Guangdong, Guangzhou, 510006, China) （广东科技大学自动学院 广东市广州510006,China）[/align] Abstract: This article discusses the PROFIBUS-DP control of the logistics of conveyor belt. According to the actual needs of logistics monitoring, a monitoring system hardware and software design was completed, and the PLC control of conveyor belt campaign materials barcode, color, weight, shape and size of the data collection were performed, such as access to materials warehouse operation. Keywords : PROFIBUS-DP; PLC; Transmission Belt 1 Overview Automated logistics conveyor belts have been applied to various departments of industrial production and are widely used in automobile, food, pharmaceutical, machinery processing and electronic component production lines, playing a pivotal role in the country's industrial production. With the emergence and development of modern logistics equipment and industrial buses, logistics systems and production manufacturing systems are organically integrated to form a complete production system [1]. This brings about the problems of complexity of control and communication structures and implementation difficulties. Against this background, this paper proposes a logistics conveyor belt coordination control scheme based on PROFIBUS-DP fieldbus. PROFIBUS fieldbus [2] is a standardized specification formulated by companies such as Siemens, including: FMS for communication between master stations; PA for communication between slave stations in the process industry; and DP for communication between slave stations in the manufacturing industry. Therefore, this paper studies and designs a logistics monitoring system based on PROFIBUS-DP fieldbus to monitor the data acquisition of each workstation on the production line and control the operation of the production line conveyor belt. 2 System Hardware Structure The logistics conveyor designed in this paper is responsible for the storage and retrieval of product materials, transportation, barcode detection, electronic tag detection, product material color detection, product weight detection[3] and other links. It is an important part of the entire industrial product production, processing and transportation process. The hardware structure of the logistics conveyor based on PROFIBUS-DP is shown in Figure 1. [align=center] Figure 1[/align] The system is divided into two layers: PROFIBUS-DP master station S7-300, slave station S7-200, and industrial control computer connected through bridging module PQ20. The bridging module PQ20 is mainly used for protocol conversion, converting the computer's serial port RS232 protocol into the PROFIBUS-DP RS485 protocol. Specifically, it mainly consists of the following five parts: (1) The main station S7-300 is mainly responsible for the motion control of the green conveyor belt between the barcode and touch screen workstations and between the shape and size workstations after corners 1, 2, and 3. It collects the workstation working status information (including whether the workstation is busy or not, and whether it is in operation) and workstation data information (including material barcode data, etc.) sent by the PQ20 bridging module of each workstation, and then sends it to the main control for processing through the PQ20 bridging module of the main control computer. (2) The slave station conveyor belt S7-200 is responsible for the motion control of the green conveyor belt before corners 1, 2, and 3, corner rollers, lifting, rotary motors and roller motors at round corners. (3) The slave station color touch screen workstation S7-200 is responsible for the motion control of the roller conveyor belt of this workstation and communicates with the We In View touch screen MT506S. The touch screen is mainly used to display the product material color and barcode data. (4) Industrial control computers at each workstation, including the workstation for collecting barcode electronic tags of logistics product materials, electronic weighing workstation, shape detection workstation, size detection workstation, and stacker crane loading and unloading workstation. The industrial control computer program is written in VB and is mainly responsible for the hardware control of this workstation, as well as sending the workstation's working status information (including whether the workstation is busy or not, and whether it is in operation) and the information of the workstation's collected data (including material barcode data, etc.) to the bridging module PQ20 via the serial port. PQ20 completes the protocol conversion, converting RS232 to RS485, and the workstation information is transmitted to the master station S7-300. It completes the PROFIBUS data acquisition task. (5) The information collected by the S7-300 from PROFIBUS is also communicated with the main control computer through the bridge module PQ20. Therefore, the main control computer is also a slave station of PROFIBUS. After the data arrives at the main control, the monitoring software written in VB can display the working status of each station and various information of the product materials. Moreover, the VB program of the main control is also responsible for storing various information of the product materials into the MS SQL database to save the information. The following is an overview of the workflow of the logistics production line, as shown in Figure 2: [align=center] Figure 2[/align] 1) The product materials are taken out from the warehouse by the stacker crane robot arm, placed on the roller conveyor belt, and conveyed to corner 1; 2) After the corner 1 is lifted and rotated, it is determined whether the barcode station is busy. If it is busy, the product materials stay on corner 1. If it is not busy, the product materials are conveyed to the barcode electronic tag station. 3) After the barcode station successfully reads the barcode and electronic tag, it checks if the color touchscreen station is busy. If not, it transfers the product material to the color touchscreen station and simultaneously sends data to the S7-300 via PROFIBUS. 4) After the color station reads the color data, if corner station 2 is not busy, it sends out the product material. If the electronic weighing station is also not busy, corner station 2 sends the material to the electronic weighing station. The color station's S7-200 sends data via PROFIBUS. 5) After obtaining the weight of the product material, the electronic weighing station also checks if the next station is busy. If not, it sends out the material and simultaneously sends the station status and data to the S7-300 via PROFIBUS. The remaining shape and size stations similarly complete the data collection and transmission for their respective stations. 6) After passing through the roller conveyor belt, the product material has obtained all the data and will be sent to the finished product warehouse. It will then return to the stacker crane loading and unloading station. Before being sent to the finished product warehouse, it will be judged whether all the material information has been collected. Otherwise, it will return to the production line to collect the data again. If the data collection is completed, it will be sent to the finished product warehouse to complete the workflow of the material production line. 3 System Software Design The software part mainly includes S7-300 hardware configuration [2], DP address allocation, input and output byte address of slave station, belt and roller control program of S7-300 and S7-200, data collection and forwarding program of S7-300 and main control industrial computer, and VB program design of main control and other 6 stations. The main station S7-300 needs to coordinate the control between S7-200 and other 6 stations. In addition to completing the data collection of their own station, the 6 stations also need to send information to the main station S7-300. The PROFIBUS-DP master station uses an S7-300 CPU313C-2DP, and the slave stations use an S7-200 CPU226, with a communication rate of 1.5M/s. PROFIBUS communication between the S7-300 and S7-200 requires the EM277 module; therefore, in the hardware configuration, the EM277 module is used instead of the S7-200. Each workstation's industrial computer is also a slave station, connected to PROFIBUS via a bridging module PQ20. After installing the GSD file, the PQ20 module can be called in the hardware configuration. Because of the use of the PROFIBUS-DP fieldbus, communication between the master station and each slave station does not require a dedicated communication program. Only the PROFIBUS bus DP address, input/output byte address, and number of bytes need to be configured in the S7-300 hardware configuration, as shown in Table 1 below. [align=center] Table 1[/align] The communication between the master station S7-300 and the slave station S7-200 requires the EM277 module. The DP address of the EM277 in Table 1 above needs to be consistent with the rotary switch on the actual EM277 module used. The master station S7-300 sends the information from its output area to the output buffer (called the "receive mailbox") of the slave station, and the slave station returns the data from its input buffer (called the "send mailbox") to the input area of ​​the master station. In this way, the master station completes the data exchange with the slave station. When configuring the hardware of the EM277, the offset of the V memory [2] is set to 0. For the EM277 of the conveyor belt station, since the input and output area of ​​8 Bytes Out/8 Bytes In is selected, the output data (from the master station S7-300) is placed in VB0 of the V memory, and the input data (transmitted to the master station) is taken from VB8 of the V memory. The following Table 2 is the byte address of the I/Q area of ​​the S7-300 corresponding to the V memory of the S7-200. Table 2 coordinates the control between the S7-300 main station and the S7-200 conveyor belt, as well as the other six workstations. This requires determining the workstation's operating status. For example, after the color touchscreen workstation receives the product's color data, it checks if the preceding corner 2 is available. If it is, the baffle lowers, allowing the product material to enter corner 2. After corner 2 completes the lifting and rotation with the product material, it also checks if the preceding electronic weighing workstation is available. If it is, the roller conveyor belt is activated to send the product material out. The following is the flowchart for corner 2, Figure 3. The material data collected by each workstation is sent to the main control computer via PROFIBUS-DP and then stored in the MS SQL 2000 database of the main control computer. The computer program is written in VB. VB uses ADO objects to perform insert, query, and delete operations on the MS SQL 2000 database, recording data such as barcodes, electronic tags, product colors, and product weights for each product. The following is VB program code to create a record storing material product data, using barcode data as the primary key. `Public gadoConnect As New ADODB.Connection ' Creates a new ADO Connection object Dim strSQL As String strSQL = "INSERT INTO MASTER (barCode, eleLabel, Stat) " ' barCode is the barcode field name ' eleLabel is the electronic label field name ' Stat is the workstation number field name strSQL = strSQL & "VALUES ('" & temp_Bracode7 & "', '" & temp_Elabel6 & "', 2)" gadoConnect.Execute strSQL ' Writes the barcode and electronic label to the MASTER table in the database 4 Conclusion This logistics production line monitoring system design has been put into application and is operating well. It can meet the requirements of small and medium-sized logistics production lines. Using the PROFIBUS-DP fieldbus, it achieves relatively inexpensive and high-speed data transmission, saving hardware quantity and investment, reducing maintenance costs, and improving the accuracy and reliability of the system.` With the development of logistics, PROFIBUS fieldbus will be used more and more widely in logistics production lines. References [1] Wang Guohua. Modern Logistics Technology and Equipment [M]. Beijing: China Railway Publishing House, 2004. [2] Zhang Yungang, Song Xiaochun. Siemens S7-300/400 PLC Technology and Application [M]. Beijing: People's Posts and Telecommunications Press, 2007. [3] Ma Tengyuan. Discussion on the Design Technology of Real-time Logistics Monitoring System [J]. Modern Electronics Technology, 2007, (19): 12-13. Author Introduction: Chen Guojian, male, master's student, research direction: intelligent control system and application. Detailed contact information: P.O. Box G162, Guangdong University of Technology, No. 100, Waihuan West Road, Guangzhou University Town, Guangzhou. Tel: 15902054954. Postcode: 510006. E-mail: [email protected]