基于FPGA的开放式数控系统手持单元接口的设计

Design of handheld unit interface based on FPGA in open CNC system

针对“PC+可编程I/O接口卡”体系结构的开放式数控系统的需要,研究了基于“可变频率脉冲均匀倍频”方法的数控手持单元接口,利用可编程I/O接口卡上的现场可编程门阵列(Field Programmable Gata Array,FPGA)通过边沿提取,提高手持单元脉冲分辨率,利用边沿时间间隔作为均匀倍频依据,并通过设置缓冲区防止计时值丢失。所开发的接口可以克服现有手持单元接口的脉冲序列倍频输出频率固定以及封闭性的缺点。仿真结果表明,手持单元接口能够根据手轮旋转速度变化输出均匀脉冲,同时实现了手持单元的即插即用。

Aiming at the requirement of open CNC system based on PC with programmable I/O interface card architecture,studied the interface of CNC handheld unit based on variable frequency pulse uniform frequency doubling method.Using the FPGA on the programmable I/O interface card,the pulse resolution of the handheld unit was improved by edge extraction,the edge time interval was used as the basis of uniform frequency multiplying,and the loss of timing value was prevented by setting a buffer.The interface can overcome the shortcomings of fixed output frequency of existing handheld unit interfaces and the closure of handheld unit interface in commercial CNC system.The simulation result shows that the interface of handheld unit can output uniform pulse according to the change of handwheel rotation speed,and make plug-and-play of handheld units possible.