DAQCard 6533 in Change Detection Setup

[Tired and alone]

Hello

I have set up my DAQCard 6533 for change detection using ports C and D. I feed an internally generated trigger signal, of duration 10uS at a repetition rate of 10KHz into one of the lines of port C and use this to initiate data input multiple times. The idea being that when the card sees a change on the port C line it takes data in on both ports. I then mask off the undesireable data to leave the valid data, coming in on port D. However, I seem to get twice the amount of data I was expecting. For instance if I apply 200 trigger pulses I get 400 data inputs? Is this because the DAQCard does not distinguish between the rising and falling edge of the trigger signal, effectively seeing two changes happening? My local s
ales engineer was unsure about this. Any guidance would be gratefully appreciated. Or am I doing something silly within my setup of the change detection?

[bman]

Yes, you are correct, the DAQCard is seeing two changes every pulse, one at the rising edge and one at the falling edge. If you think of it in terms of value, if the line starts off low, 0, then goes high, 1, then low again, 0, that's two changes, 0->1 and 1->0.

Brian

[Tired and alone]

Thanks Brian

I assumed that was the case but my local sales guy couldn't confirm it.