What commands do you use to talk to a GPIB instrument in C#, visual studio? I need to be able to write commands to the instrument and read the output.
I use Agilent IO Library Suite.
Here is a tutorial to use it on C#: I/O programming examples in C#
Nevertheless, in my company we had stability issues with the VISA-COM implementation, so we wrote our own wrapper around the visa32.dll (also part of the IO Library suite) using P/Invoke.
(Disclosure: I work in a company that make intense use of GPIB instruments)