原来用5v485工作正常，后来做低功耗，改3.3v485，出问题了，发送正常，无法接收，电路没变，连接9013的两只电阻，换成了6.2k，原来是10k，AB两端没加
上拉和接地电阻，后来接上两个6.2k,也不行，上来就接收到乱码，
6.2k电阻是换算过来的，由5v,我给厂家发信，回答是
Now that you have changed to a 3.3V part and pull-up is now going to 3.3V instead of 5V you will need to change values of divider such that it will provide >200mV at Receiver input when cable is disconnected.
，那位兄台做过指点一下，电路图是经过测试的5v系统，正常收发
多谢多谢
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