
   我厂USB转串口芯片方案有两种：

1、340芯片方案，是单IC方案，输出电平为RS232电平（9V），非TTL电平（5V），可用在PLC工业控制、路由器调试、串口通信。市面上其它工厂有非340的单IC方案，如单IC的PL2303方案，输出为TTL电平（5V），不能用在PLC工业控制、路由器调试、串口通信，只能用在编程器上。

2、pl2303+211方案是双IC方案，输出电平也是RS232电平，211芯片的作用是将PL2303输出的TTL电平（5V）转换成RS232电平（9V），可用在PLC工业控制、路由器调试、串口通信之外，还可以接MODEM，串口鼠标。



Our usb to rs232 have two categories chip: 

1、340-chip program, the chip is a single IC, the output voltage is rs232 voltage (9V), non-TTL voltage (5V), can be used in industrial controls(PLC), Debug routers,  serial communication. Other  factory has non-340 single-IC chip such as the PL2303 single IC chip ,the output voltage is TTL voltage (5V), can not be used in industrial controls(PLC),debug  router , serial communication, can only be used for programming unit .

2、pl2303+MAX211 program is two ic program,the output voltage is rs232 voltage (9V),MAX211 Can chage the pl2303 output voltage (TTL voltage 5V) to rs232 voltage (9V), Can be used in industrial controls(PLC),debug router,serial communication,also support MODEM,serial mouse,etc.



































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