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Well. It depends if you are a LabVIEW island in a C [sic] of programmers. Then you only have to learn that you *must* specify the DLL function prototypes and keep shouting "Threadsafe, Threadsafe, Threadsafe" until their ears bleed No need to learn C/C++ then I think every LabVIEW programmer should have a pet C programmer

As has been said you want to play around with the routing table on a windows machine. Read up about the net route command https://technet.microsoft.com/en-gb/library/bb490991.aspx and windows routing in general, you will need http://serverfault.com/questions/510487/windows-get-the-interface-number-of-a-nic to get the if interface for the route add. I have PC's fitted with two NIC I ping out of NIC 1 to an IP wireless device across to air into another IP wireless device and then back into NIC 2 on the same PC. I can also with this setup do Iperf across the air and telnet out the each NIC as desired. Without setting up the routing table correctly, I would in truth just ping and Iperf across the backplane of the PC from one NIC to the other, but the routing ensures I go out one NIC. I do all this with LabVIEW and net route commands issued as system exec calls, it works well. I tend to delete all all routes and then set up my own. If you do this remember to alos add in a route to your network for the main PC LAN or you cannot get to internet or local server :-) Also note if any NICs are disabled or enabled, Windows will try and be clever and sort out the routing as it see's fit and break your rules, so to help overcome this I nearly always have a simple powered dumb Ethernet switch hanging on the NIC between my test device and PC, then if I power off my test device to NIC still sees a good active connection to something.

No. You'll need to tell the operating system what the preferred route is to the server. In Windows you can set network priority so that it will preferentially use a particular network card (for all connections), or use the command-line "route" command to set up a route specifically to your destination. You could do a system exec call to set that up before opening the TCP connection. I had to do something similar with a device that insisted that its MAC address be manually added to the arp table before it could communicate.