Question: I want to connect three bar code readers using three RS 232 ports, and take the ethernet port to a plc to read the bar codes. Can serial device server USR-N540 meet my demand?

Answer: USR-N540 can reach the need you want, you can make USR-N540 work at TCP Client mode, PLC work at server mode, the setting method is simple, you can refer to article.

Question: Hi. The plc will need to read ASCII string from the bar code scanner will the ASCII string come from the USR-NS520/USR-N540 on TCP? 

Answer: The N540/N520 can transparent transmission data, so no matter what you send from serial port , the LAN port can receive the same string.

Question: If I connect three bar code scanners and all bar code scanners are reading bar codes at the same time will the ethernet port send all three strings at the same time and how will I know which string came from which scanner. 

Answer: You can set different registration package for different com, the registration package can send with the data.