visa read & write

[marwen_saafi]

How can I use visa (serial port) to write in COM and read from another.

[crossrulz]

What language are you using?  C++? C#? LabVIEW? LabWindows/CVI?

Regardless, there should be some really good examples available to you.

[marwen_saafi]

i'm using labview

[crossrulz]

Then look in the Example Finder (Help->Find Examples) and do a search for Simple Serial Write & Read.  It is an ok example of how to perform a write to an instrument and then read data coming back from it.  You should be able to easily expand it to write on one port and read on another.