high speed output of custom bits

Hi all.

I am building my own communication message protocol and I am looking for NI device or HW to output voltages of 0s (<2.5V) and 1s (>2.5V up to 5V) at speed of 1 micro-sec per bit. Lets say 1 = a transition from 0 (holding for 0.5 micro-sec long) to 1 (holding for another 0.5 micro-sec long) to make the one bit = 1 micro-sec.

I have a USB-6001 device, but if I use DIO or AO channels, I can only switch between 0s and 1s every 1 msec, which is slow. Even if I have the switching done in a for-loop using NI-DAQmx software package. I am using Visual Studio C++ for my src.

Anyone has any thoughts of what NI device i can use? or maybe I should use something different than Visual Studio?

thanks