Design and Implementation of PC-based CNC Software (3)

. Implementation of interrupts in Windows environment

Windows is a non-exclusive multitasking system in which an application receives input through an application queue, and then the message loop gets the input message from the application queue and sends it to the appropriate window. In this mode of operation, real-time control is more difficult. However, from another perspective, the user's keyboard, mouse, and timer inputs are hardware interrupts, and the device drivers provided by Windows are actually interrupt service routines. Since the actual processing requires high real-time performance, it is necessary to implement a real-time task by means of interruption. Since interrupts can occur at any time, and are not limited to applications running on the device, the interrupt service routine must be in a fixed code segment. In the large frame EMS memory configuration, only one type of code can be used to perform such interrupt service at any time. This type of code is the code in the fixed code segment of the dynamic link library (DLL). Under the premise of ensuring reliability, DLLs must be used to implement interrupts. The use of DLL in our system to achieve hardware interrupts, reliable operation.

Replace the system enclosure and become a dedicated system

Progman.exe in Windows is the shell of Windows. It is an important part of Windows, but it is not a necessary component in Windows. Every user can compile their own shell. Since the CNC system is directly connected to the production equipment, the user often hopes that the CNC system is a dedicated system. In addition, Windows itself is a multi-tasking system. Simultaneous execution of multiple applications may cause conflicts between programs. Therefore, it is necessary to perform Windows. Transformation, transformation method is very simple, using CNC software instead of Windows "Shell" - Progman.exe, so that Windows directly runs the CNC software after startup, in the user's operation, can not feel the existence of Windows, while avoiding the application A conflict between hardware and software.

2 afterword

The PC-based CNC is an inevitable trend in the development of NC technology. It guarantees that the basic hardware and software of CNC is continuously updated with PC technology, so that NC technology can closely follow the development of PC technology, and the development results of PC can be directly applied. Saving development costs and shortening the development cycle are of great significance.

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Angular Contact Ball Bearing

Angular contact ball bearings mainly bear large unidirectional axial load. The greater the contact angle, the greater the load bearing capacity. The material of cage is steel plate, brass or engineering plastics. The forming method is stamping or turning. It is selected according to the bearing form or using condition. Others include combined angular contact ball bearings, double row angular contact ball bearings and four-point contact ball bearings.