基于51单片机的学习资料！里面有串口通信232的程序资料和原理图（protel99）！程序清晰明了！注释的很清楚便于学习！-51 single-chip-based learning materials! There are 232 serial communication program information and schematics (protel99)! Program clarity! Note the very clear easy to learn!

利用protel制作的232串口到485串口的收发转换电路，利用的3.3V的MAX3326,功耗小，稳定性高，带有光耦隔离-Protel produced using to 232 send and receive serial conversion circuit 485, the use of 3.3V, MAX3326, power consumption, high stability, with optical isolators

基于PC串口232和485之间的通信转换，protel的PCB图附带原理图-232 to 484 that uart of computer