I. Overview With the rapid development of computer application and network technologies, the functionality of CNC systems has been greatly enhanced. Due to the generally positive outlook for Ethernet, major CNC manufacturers have launched CNC systems with Ethernet capabilities. In the field of Distributed Numerical Control (DNC), a new type of CNC machine tool network has also emerged—Ethernet-based DNC. Ethernet connectivity refers to networking CNC machine tools such as machining centers with Ethernet capabilities via Ethernet, enabling centralized control of multiple CNC machines from a single microcomputer. The network structure is shown in Figure 1. In this approach, DNC software developers typically need to perform secondary development based on the development software packages provided by the CNC manufacturer, specifically developing their own communication interface software for different CNC systems. The Ethernet-based CNC machine tool network control system JCSDNC (Ethernet) introduced in this article is developed for FANUC systems and is suitable for networking machine tools equipped with FANUC 0iB/15i/16i/18i/21i and PowerMate iD/H systems. II. Requirements for CNC Systems in Constructing an Ethernet Monitoring Network Machine tool Ethernet monitoring networks require CNC systems to have Ethernet functionality in hardware, i.e., an Ethernet card or Fast Ethernet card, and in software, the CNC must have built-in Ethernet functions. Its internal communication processing mechanism is shown in Figure 2. For built-in Ethernet cards, communication is processed through the CNC's CPU. This means that the CNC's operating conditions affect the communication of the built-in Ethernet card, and correspondingly, the communication status of the built-in Ethernet card also affects the CNC's processing. Figure 2 shows the internal communication mechanism based on Ethernet. The processing priority of built-in Ethernet functions is lower than the following operations: motion control of each spindle in automatic or manual mode. Therefore, the communication speed will decrease during automatic operation. On the other hand, since the priority of built-in Ethernet functions is higher than CNC screen display operations, C language executors (except for high-level tasks), and macro command executors (except for executing macros), these operations will be delayed when performing built-in Ethernet communication. The network transmission speed of Ethernet connections is significantly higher than that of serial ports, with transmission rates reaching 10M or 100M per second. Furthermore, because the CNC system of the machining center has some built-in function interfaces, Ethernet connection enables direct communication between the control computer and the CNC system. This means that not only can rapid data transmission be achieved in this way, but also complete equipment and production information can be automatically obtained from the main control computer, allowing for remote control of the machining center and creating more comprehensive conditions for automated production. To better adapt to production needs, the CNC machine tool network control system needs to have four functional modules in addition to the traditional DNC software: an NC program management module, a field monitoring module, a remote monitoring module, and a data communication part for remote access via the Internet. III. Functional Modules 1. NC Program Management Module As one of the important resources in the machining process, efficient data management of the NC program has become an indispensable part of DNC software. NC program management is divided into lifecycle management and internal information management based on the management target. This module provides strict management of the entire lifecycle of the NC program, from its creation to its destruction. At different times, the NC program status can be set to three types: editing, review, and finalization, as shown in Figure 3. The initial state of the program is freely editable, and trial processing can begin after review. Once the program has been verified through trial cutting, it reaches a finalized state and can no longer be edited until it is deleted. Figure 3 shows the lifecycle of an NC program. 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. In this system, programs can be searched using multiple conditions such as drawing number, part name, operation, and machine tool. The system also manages the machining program editing history, the list of tools used, and process cards. 2. On-site monitoring module The on-site monitoring module is the foundation for realizing a remote monitoring system. Direct connection to a CNC machine tool with Ethernet capability via Category 5 or Category 5e cable enables control, monitoring, and diagnostics of the CNC machine tool. Furthermore, some software manufacturers on the market currently connect machining centers with only serial communication capabilities via Ethernet or even wirelessly. These two methods are fundamentally different from Ethernet connections; they merely change the connection method through an adapter, converting serial data into Ethernet transmission. The communication bottleneck still lies in serial communication. However, this approach overcomes problems such as harsh factory construction conditions and inconvenient wiring. This module 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. By processing the collected operating data, data needed for production management, such as machining performance and machine tool utilization, can be obtained promptly, as shown in Figure 4. Figure 4: Efficiency Statistics 3. Remote Monitoring Module 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, as shown in Figure 5. It can even transmit the machine tool's ladder diagram to a remote control host for remote fault diagnosis using the ladder diagram. To ensure production safety, the ladder diagram must be password protected to prevent unauthorized modification. Figure 5: Remote Monitoring of Production Status. 4. Internet-based Data Communication Module. Due to the ever-changing production conditions and the many random situations that may arise during production, professionals from different locations and departments need a platform for free communication to work on the same equipment. This allows for information exchange and experience sharing via the network, ultimately enabling remote monitoring of the equipment. This module provides a text communication platform based on network technology, as shown in Figure 6. Figure 6: Remote Interaction Platform. IV. System Initialization. The Ethernet function of the FANUC system is implemented through an Ethernet card or FANUC Fast Ethernet card following the TCP/IP protocol. For the network control software to communicate normally with the CNC machine tool, the following settings are required: • Configure the TCP/IP protocol on the control computer side; • Configure the Ethernet card and built-in Ethernet functions on the CNC side; • Physically connect the personal computer and the CNC. V. Application of JCSDNC (Ethernet) The biggest challenge of Ethernet connectivity lies in the high requirements placed on CNC systems. Specifically, the CNC system must have Ethernet functionality, which is only achievable with high-configuration CNC systems. Furthermore, because different CNC manufacturers provide different development kits for Ethernet functionality, system integrators must perform relatively independent development work for different CNC systems. In machining environments with multiple CNC systems, the compatibility of each subsystem becomes particularly important. Ethernet-based remote monitoring systems offer significant advantages over traditional network models in terms of transmission speed and control of underlying devices. They also provide more convenient and faster hardware connections, basically meeting the production status control needs of small and medium-sized enterprises in the machining and manufacturing process.