I am attempting to generate a signal which will be used as a marker during later data analysis. This signal will eventually be included with 7 other signals which will all be acquired during a sleep study. In my main program, which is too involved and I will not post here, the signal will change from outputting a constant 5 volts to 0 volts or vice versa. In order to make this diagnosis easy, I am trying to use the VI included below to update the signal immediately. I understand that the NI-6218 DAQ device has its own onboard buffer but when I try to get around the buffer by changing the Regen mode to "Not Allow Regeneration", or changing the Output.onbrdbufsize, or by changing the AO.DataXferReqCond, it doesn't work. I need the signal to immediately update so it marks the correct time (hopefully within a tenth of a second). The VI included below will represent this by changing from a sign wave to a triangle or square wave, but the generation of the new signal is not immediate. It seems to take a few seconds for the updated signal to propagate through the onboard buffer. Is there a way around this that I have not found so that the signal will be immediately updated and output as soon as a user pushes the button on the front pannel?
Software: LV15
DAQ: NI USB-6218