My background includes 15 years of programming PLC's.
AO's were simple. You passed the
AO a value between preset ranges and it
output a proportional voltage signal based on the hardware capabilities.
I foolishly thought LabView and DAQ AO's would be about the same. I built a vi to generate a DC signal which I could control the amplitude of. I also tied it to a chart to monitor how it worked. I managed to draw some very pretty ramping pictures on my chart, but when I put a DMM across the physical terminals I see no voltage.
Then I used MAX to test the channel and measured it again. Now I see voltage on my DMM. I was attempting to use the DAQ Assistant to do this. Do I need to force it to re-read the changing value I am sending it? All of the examples I find show me more primitive methods, and I could not seem to get any of them to do what I want either. I need to send a speed reference to a DC drive.
My incorrect method was to recursively add a value for ramping the signal up or subtract to ramp down. This method works perfectly on an industrial PLC. I connected a chart to the signal just as it entered the DAQ Assistant, but the only way I could check the actual was with the DMM.
Are there any examples that use the Assistant? If not then I guess I will have figure out how to use the primitives anyway.
technomage
