说明：  最近编写的S7-200与4台安川伺服以及位移数显表RS485通信，已经应用在项目上，很稳定。但基于485通信的特点，速率有些慢，大家注意！
(S7-200 recently written with four Yaskawa servo and displacement DRO RS485 communication, has been used in the project, is very stable. But based on the characteristics of 485, the rate is somewhat slow, pay attention!)