Hello Andrew, Setting your buffer size to be the same size as your array is typically what is done. The buffer size is not in bytes, but in samples. Please take a look at some of the example programs that ship with LabVIEW. Go to Help >> Find Examples >> Hardware Input and Output >> Trad. DAQ(LV 7.x only) >> Analog Output >> Generate Continuous Sinewave.vi.
If you take a look at this VI, you will see that a sinewave array is produced using a FOR loop. This FOR loop generates an array that has the same number of samples as the buffer length input of AO Config. Take a look at this VI and see if you are able to modify it to fit your needs. In some cases, you may need to use a buffer that is larger than your actual data. This may be the case if your data array is generated dynamically and is not always consistent in size. The only size restriction in this case it that you are able to find a continuous section of memory that can accommodate the buffer. Let me know if you need additional assistance with this issue. The example programs should be a great reference. Regards, Bill B Applications Engineer National Instruments