As a controller, Send and ibwrt do nearly the same thing. They do take different parameters (Send takes an address to write to and will address the bus by itself, whereas ibwrt does not take an address and gets that information from a device-level descriptor which is passed to it, or a board level descriptor, in which case it will not do any addressing). Assuming you're writing a controller application and can use either, it doesn't really matter which ones you use. Do not, however, mix "multidevice calls" like Send and Receive with "board level" or "device level" calls like ibwrt and ibrd.
Hope this helps.
Scott B.
GPIB
National Instruments
