2.2 Hardware of CNC system
According to the number of microprocessors (CPUs) in the numerical control device, the numerical control system can be divided into single microprocessor system and multiple microprocessor system. Modern CNC devices are mostly modular structures with multiple microprocessors. Economical numerical control devices generally adopt single microprocessor structure, while advanced numerical control devices adopt multi-processor structure. Multi-processor structure can make CNC machine tools develop towards high speed, high precision and high intelligence.
2.2.1 Numerical control device with single microprocessor and multi microprocessor structure
Table 2-3 describes the numerical control devices with single microprocessor and multiple microprocessor structures in detail.
Table 2-3 Numerical Control Device with Single Microprocessor and Multi-processor Structure
| Number | Processor type | Detailed description | |
| 1 | Single microprocessor | Stand-alone system | The entire CNC device has only one CPU, which centrally controls and manages the entire system resources and realizes various CNC functions through time-sharing processing. This CPU not only processes the input of the keyboard and CRT display, but also performs real-time processing such as decoding, tool compensation calculation and interpolation. In this way, the feed speed is obviously affected by the fact that there is only one CPU in the entire CNC device, which centrally controls and manages the entire system resources and realizes various CNC functions through time-sharing processing. The CPU should not only process the keyboard input and CRT display, but also perform real-time processing such as decoding, cutter compensation calculation and interpolation, so the feed speed is obviously affected |
| Master-slave structure | In the CNC system, only one CPU (called the master CPU) has the control and use right to the system resources. Other functional parts with CPU can only accept the control command or data of the master CPU, or send request information to the master CPU to obtain the required data, which is in a subordinate position. Therefore, this structure is called master-slave structure, which is also classified as single-microprocessor structure | ||
| 2 | Multi-processor | Multi-CPU architecture | Multi-processor structure CNC device means that there are two or more CPUs in the CNC device, that is, some functional modules in the system also have CPUs, which can be divided into multi-master structure and distributed structure according to the relationship between components |
| Multimaster structure | There are two or more modules with CPU in the system that control or use the system resources. Modules adopt tight coupling (correlation and dependency) and have centralized operating system. Solve bus contention through arbiter and exchange information through common memory | ||
| Distributed structure | The system has two or more functional modules with CPU. Each module has its own independent operating environment. Loose coupling is used between modules, and communication is used to exchange information | ||
