I have used the old SmartBits 200 with LabVIEW. What exactly is the name of the dll you got from Spirent? There was one dll that could be used in C/C++ but not in LabVIEW because LabVIEW does not have the correct datatypes. A wrapper dll is required to do the conversion. We had gotten the wrapper and a fairly complete set of VIs from Spirent. The wrapper we got used several clusters to pass information and this was all documented in the .h file that came with the wrapper. I think the wrpapper and VIs was something we had to pay for and in any case, I'm sure they would not work with the 6000. You might want to check with Spirent about this. Can you attach the .h file or any other documentation on the dll you got?