Hi, I have the same problem. I want to build communication between several RS232 devices(Mass flow controller) via Ethernet, and I have connect them in this order: Mass flow controller--IOLAN(terminal server which can connect up to 8 serial ports, and convert them to Ethernet connection)-Switch-computer. I can't find new com port via device manager and MAX, so I wrote some program with TCP/IP vi. However, when i send command through write.vi to serial device, I can't get response from read.vi, and I got error code"56" from write.vi. I am wondering whether there is something wrong between communication of IOLAN and serial devices, because I am sure the connection between IOLAN and computer is right. Please give me some suggestions. Thank you.