[Abstract] Addressing the problems existing in current CNC equipment communication and the shortcomings of several DNC networking methods, this paper proposes a CNC machine tool network control system based on industrial Ethernet and its structure, and elaborates on the system's functions. An ARM-based embedded protocol converter is designed as a key component of the system, realizing the conversion between the industrial Ethernet protocol and the CNC machine tool's RS232 serial port protocol. [Keywords] CNC machine tool, industrial Ethernet, embedded system. Networking CNC equipment and computers in a manufacturing workshop to form a DNC (Distributed Numerical Control) system has become one of the core technologies urgently needing to be solved to achieve CAD/CAM integration and computer-aided production management integration. The implementation of the communication network is the most critical technology in building an integrated DNC system. It generally includes two layers: the upper layer is the communication between the DNC host and the CAD/CAM/CAPP, MRPII system, and the lower layer is the communication between the DNC host and various CNC equipment in the workshop. There are many methods for networking CNC machine tools, such as serial communication, MAP communication technology, fieldbus, and Ethernet. Although these communication methods have achieved networking of CNC machine tools to a certain extent, they all have some shortcomings in application. To improve the integrability and real-time scheduling capabilities of CNC machine tool network control systems, this paper proposes a CNC machine tool network control system based on industrial Ethernet. 1. System Structure The system structure is selected primarily based on actual needs, taking into account factors such as the workshop environment, the factory's automation level, and information integration with management. The system uses industrial Ethernet as the network platform. The anti-interference design of industrial Ethernet ensures smooth communication and real-time performance even in harsh workshop environments, and it is easy to integrate with management. The system adopts a bus + star topology. The backbone network uses a bus structure, which is easy to form a redundant ring network. Locally, a star structure is used to avoid the failure of one device affecting other devices. The system topology is shown in Figure 1. The protocol converter that connects the CNC machine tool and the industrial Ethernet is essentially a converter between industrial Ethernet data packets and RS232 data packets. It connects to the industrial Ethernet using an industrial-grade RJ45 interface and connects to the CNC machine tool with an RS232 serial port. The protocol converter can be installed on the CNC machine tool as a component. 2 System Functions 2.1 Communication Functions (1) Bidirectional Transmission of NC Programs All CNC equipment is networked and centrally managed. The network is used to transmit NC programs (including machine tool parameters, tool compensation files, macro programs, etc.) bidirectionally, thereby realizing the massive storage and integrated management of NC programs. Each CNC machine tool is defined as a client device. Using the communication port (usually RS-232) and communication function of the CNC system itself, the operator can perform bidirectional data transmission and access all operations of the data on the management server at the CNC machine tool end. The server end automatically processes the operation requests of the CNC end without human intervention. Ensure that all networked CNC equipment can perform concurrent communication transmission at the same time. (2) Online Machining The CNC system itself needs to support online machining function, and can realize functions such as breakpoint resume transmission and subroutine call. (3) Data Sharing Allows the operator to access information of other CNC equipment or virtual machine tools on the local CNC equipment, which facilitates the transfer and machining of parts. 2.2 Control Functions In this module, the DNC server communicates with the CNC machine tool, enabling real-time acquisition of machining status, network status, tool information, operation history, and tool life management. With proper authorization, various equipment and operating parameters can be modified online, achieving complete monitoring of the underlying equipment. Processing the collected operating data allows for timely acquisition of data needed for production management, such as machining performance and machine tool utilization. Due to the volatile nature of production conditions and the many random situations that arise, a platform for free communication is needed for professionals in different locations and departments to work on the same equipment. This allows for information exchange and experience sharing via the network, ultimately achieving remote equipment monitoring. The remote monitoring module utilizes computer and network technologies to provide a platform for sharing resources over a wide area and supports real-time monitoring and fault diagnosis. Users can query equipment operating status and on-site operating conditions at any time via the network, enabling real-time remote monitoring of the production process. 2.3 NC Program Management As a crucial resource in the machining process, efficient data management of the NC program has become an indispensable part of the DNC system. NC program management can be divided into lifecycle management and internal information management, depending on the management target. Managing the internal attributes of an NC program mainly includes managing the program number, program comments, part drawing number, machined part number, machining operation number, machining range, machine tool, and user information. This system allows for combined searches of programs based on drawing number, part name, operation, machine tool, etc., and also manages the machining program editing history, tool list, and process cards. Machining programs written by CNC programmers sometimes cannot meet machining requirements on the first attempt. Based on the machining process, programs are divided into four states: ① Editing – Programs are located in folders specified by the programming software. When loaded into the program library by the programmer, the associated information includes: program number, program name, program text, part number, part name, process document name, operation number, step number, author, writing date, tool list, and part image. ② Trial Cutting – Programs in the trial cutting verification stage. ③ Locked – Programs that have passed the trial cutting and are returned to the computer from the machine tool. ④ Finalization – Programs that have been reviewed, finalized, and archived. The program management process is as follows: After programmers (with editing and modification permissions) complete modifications, simulation verification, and other work, the program is loaded into the corresponding database trial cutting verification area. Simultaneously, a form is filled out to input the NC program association information. At this point, the program is in edit mode. After approval by the programming supervisor (with unlocking permissions), the program is changed to debug mode. It can then be sent to the machine tool for trial cutting or remotely accessed from the machine tool's control panel. Programs that pass trial cutting verification and debugging without errors are sent back to the database's locked area after approval by the programming supervisor; at this point, the program is locked. After approval by the technical supervisor (with approval permissions), the program is officially archived in the database, becoming read-only and cannot be modified further (only authorized personnel can modify it). The entire management process is shown in Figure 2. 3. Key System Components – Converter Design The working principle of the industrial Ethernet protocol to RS232 serial port protocol converter is to transparently transmit any information from a serial port device to any computer on the industrial Ethernet network, and also to transparently transmit any control information from the upper layer to the CNC equipment. By configuring an IP address for the protocol converter, the CNC machine tool becomes a node in the network, thereby achieving centralized management of the CNC machine tool, such as file transfer and status monitoring. The structure of the protocol converter is shown in Figure 3. The protocol converter is an embedded system. Using an ARM (Advanced RISC Machines) chip manufactured by PHILIPS as the processor, and in ARM's integrated development environment ADS1.2 (ARM Developer Suite), by porting the real-time operating system C/OS-II and TCP/IP protocol onto the chip, serial port monitoring software based on C/OS-II was developed, realizing the conversion of serial I/O data to industrial Ethernet data packets. Its working process is as follows: Once the serial port monitoring software detects data arrival on serial I/O, it triggers an interrupt. The system calls the protocol conversion interrupt service routine to convert the data into industrial Ethernet data packets, and then sends them to the management computer through the intelligent switch. The entire working process is shown in Figure 4. 4 Conclusion Industrial Ethernet communication can meet the communication requirements of CNC machine tool network control in the workshop. The DNC system based on industrial Ethernet unifies the information network of the workshop and even the entire enterprise with the DNC communication network. To achieve the integrity, transparency and consistency of information throughout the workshop, and to directly connect CNC machine tools to the Internet to realize remote information transmission, which meets the needs of network manufacturing. TT. ,_IIeVAX~ has become the trend of industrial field control development. The CNC machine tool network control system realized by this technology is reliable and easy to promote and apply in enterprises, and has broad application prospects. [References] [1] Hong Yongqiang, Chen Yongbo, Jiang Hongxia. Communication network design of heterogeneous CNC equipment DNC ​​system[J]. Journal of Instrumentation, 2003·24(4);326~328· [2] Xiong Bin. Theoretical discussion on agile DNC system[J]. Computer Integrated Manufacturing Systems, 1999,5(6)·1~7. [3] Liu Lifeng, Wang Minjie. Development of multifunctional DNC communication system for mold manufacturing[J]. Mold Industry, 2001,(4)·7~9. [4] Liu Bang. New Advances in TCP/IP Ethernet Automation Equipment [EB/OL]. http://bbs.gongkong.com/detail.asp?id:237378. [5] Kong Defang. With the {EPA standard}, “E-Network” is no longer a dream [EB/OL]. http://www.zju.edu.cn/zd~w/jd/read.php?recid:12905. [6] Tian Ze. Embedded System Development and Application [M]. Beijing: Beijing University of Aeronautics and Astronautics Press, 2005. Click to download: CNC Machine Tool Network Control System Based on Industrial Ethernet Editor: Chen Dong