Network Communication and Data Integration Technologies for CNC Machine Tools

I. Architecture Design of Machine Tool Network Communication

1. Three-Layer Network Topology

• Device Layer: Connects CNC machines, robots, AGVs, and other equipment via industrial Ethernet (PROFINET, EtherCAT) to transmit real-time control signals (cycle ≤1ms), ensuring motion control synchronization (e.g., collaborative machining error between dual spindles ≤0.01mm).

• Workshop Layer: Constructs a workshop local area network using Gigabit Ethernet, deploying edge servers for device data aggregation and preprocessing. Data transmission rate ≥100Mbps, supporting concurrent communication with 50-200 devices.

• Enterprise Layer: Connects workshop systems with enterprise management platforms via the Internet or dedicated lines to transmit non-real-time data (production plans, quality reports), using VPN technology to ensure secure cross-regional data transmission.

2. Key Network Equipment Configuration

• Industrial Switches: Must support wide temperature range (-40℃~70℃) and vibration resistance (5-15Hz), with redundant ring network functionality (self-healing time <50ms) to prevent network paralysis from single-point failures.

• Wireless Access Points: For mobile devices (AGVs, handheld terminals), adopt 5G or Wi-Fi 6 technology to ensure communication delay <50ms and roaming handover time <20ms, meeting real-time data interaction requirements.

• Gateway Devices: Used for heterogeneous network protocol conversion (e.g., Modbus to OPC UA), supporting at least 10 industrial protocol analyses with data forwarding rate ≥1000 entries/second.

II. Communication Protocols and Data Standardization

1. Comparison of Mainstream Communication Protocols

2. Core Elements of Data Standardization

• Unified Data Modeling: Adopts object-oriented modeling to classify machine tool data into three categories: equipment information (model, serial number), status parameters (spindle speed, feed rate), and processing data (cutting time, part count). Each data type has a unique identifier (ID) and data format (integer, float, string).

• Information Interaction Specifications: Establishes unified request/response mechanisms. For example, the command format to obtain spindle status is "GET/device/spindle/status," with response data including timestamps (accurate to milliseconds), status values (running/stopped/alarmed), and additional parameters (current speed).

• Semantic Consistency: Clearly defines key terms—for instance, "equipment utilization rate" is uniformly specified as "actual processing time/planned working time × 100%"—to avoid analytical deviations caused by inconsistent data statistical standards.

III. Implementation Paths for Data Integration

1. Edge Layer Data Acquisition

• Built-in Interface Development: Directly reads internal data via APIs provided by CNC systems (e.g., Fanuc FOCAS, Siemens S7-1200 Open IE) with sampling frequency up to 100Hz, supporting acquisition of real-time position (accuracy 0.001mm), program name, alarm codes, and other core information.

• External Sensor Integration: For older machines, edge acquisition terminals are added, connecting temperature and vibration sensors via RS485 (transmission distance 1200m) or Ethernet interfaces to supplement condition monitoring data. Terminals support local storage (≥16GB) to prevent data loss during network outages.

• Data Preprocessing: Performs data cleaning (removing outliers such as sudden 1000r/min spindle speed jumps), format conversion (binary to JSON), and compression (5:1 compression ratio) at the edge layer to reduce uploaded data volume.

2. Workshop Layer Data Aggregation and Applications

• Data Middle Platform Construction: Deploys workshop-level data servers using time-series databases (e.g., InfluxDB, TimescaleDB) to store real-time equipment data with write speed ≥100,000 entries/second, supporting multi-dimensional queries by device, time, and data type.

• Real-Time Monitoring Dashboard: Implements data push via WebSocket with dashboard refresh cycle ≤1 second, displaying real-time equipment status (green=running, yellow=standby, red=fault), OEE values (accurate to 0.1%), and production progress to assist scheduling decisions.

• MES System Integration: Achieves bidirectional data interaction via RESTful APIs. MES issues production work orders (including part drawing numbers, processing quantities) to machines, while machines upload completion reports (including actual processing dimensions, pass rates) to MES with data synchronization delay <10 seconds.

IV. Network Security Protection Systems

1. Layered Protection Strategies

• Device-Level Security: Enables access control on CNC systems (setting administrator/operator permissions), disables USB ports (or allows only authenticated devices), and uses encrypted protocols (e.g., SFTP) for program transmission to prevent malicious code injection.

• Network-Level Security: Deploys industrial firewalls (supporting PROFINET, EtherCAT protocol identification), sets IP whitelists to restrict device communication ranges, and uses VLAN to physically isolate machine control networks from office networks to prevent cross-segment attacks.

• Application-Level Security: Adopts TLS 1.3 encryption for data transmission (key length ≥256 bits), enables token authentication for API interfaces (Token validity ≤24 hours), and regularly audits operation logs (retained ≥90 days) to trace abnormal access.

2. Typical Security Risks and Countermeasures

• Protocol Vulnerabilities: For potential risks in OPC UA protocols, regularly updates server firmware (at least quarterly) and disables unnecessary service ports (e.g., unused HTTP 80 ports).

• Data Leakage: Desensitizes sensitive processing data (e.g., aerospace part drawings by hiding critical dimensions), restricts query permissions for unauthorized users, and requires dual approval for download operations.

• DoS Attacks: Deploys traffic cleaning functions on core switches to automatically limit traffic when abnormal flows are detected (e.g., over 1000 connection requests per second), ensuring bandwidth for normal communication.

V. Technological Trends and Implementation Recommendations

1. Cutting-Edge Technology Applications

• 5G Wireless Communication: Leverages 5G's low latency (<20ms) and massive connectivity (1 million devices per square kilometer) to enable flexible networking for mobile equipment (e.g., robotic loading/unloading), particularly suitable for complex layouts in large workshops.

• Time-Sensitive Networking (TSN): Achieves simultaneous transmission of real-time control data and non-real-time information over the same network through standardized time synchronization (accuracy ±1μs) and traffic scheduling mechanisms, simplifying network architecture. Currently piloted in automotive welding production lines.

• Digital Thread Integration: Links processing data with product design (CAD) and process planning (CAPP) data to form a digital thread 贯穿 the entire product lifecycle, enabling automatic synchronization from design changes to processing parameter adjustments, reducing change response time by 50%.

2. Phased Implementation Paths

• Basic Stage (1-3 months): Completes Ethernet transformation of CNC machines, achieves collection of equipment status (on/off/alarm) and key parameters (spindle speed, feed rate), and builds a simple monitoring dashboard.

• Enhancement Stage (3-6 months): Deploys standardized communication protocols (e.g., OPC UA), achieves data interaction with MES systems, and develops functions such as equipment utilization analysis and automatic production report generation.

• Advanced Stage (6-12 months): Introduces TSN or 5G technology, achieves in-depth integration of processing data with design and quality systems, builds predictive maintenance models, and enables remote program debugging via networks (supporting 3D simulation preview).