求翻译：　　一. 扫描技术 　　当PLC投入运行后，其工作过程一般分为三个阶段，即输入采样、用户程序执行和输出刷新三个阶段。完成上述三个阶段称作一个扫描周期。在整个运行期间，PLC的CPU以一定的扫描速度重复执行上述三个阶段。是什么意思？

I. When the PLC scanning technology put into operation, the work process is generally divided into three stages, namely the input sample, the user program execution and output refresh three stages. Completion of the three phases is called a scan cycle. During the entire operation, PLC CPU to a certa

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　　I. scan technology when the PLC after the operation, its work is generally divided into three phases, namely input sampling, and output the user program refreshes the three stages. Complete all three stages are called a scanning cycle. During the entire run, PLC CPU to a certain degree of scanning

　　First. The scanning is after PLC puts into operation, its course of job is generally divided