aquisition rate interference with diferencial mode

[asnaev]

Hi there,

I have a subvi adquiring RSE current inputs in a timed loop (sample on demand)  and i managed to reduce the iteration time to 0,200s. My objective here is to reduce the time aquisition between samples to a minimum. My problem starts when i had a diferencial configuration channel to the daq, although my aquisition rate is the same for all channels the iteration duration increases to around 2 secs. this only happens when i had a diferencial channel. Can u guys explain me why this occurs and how to solve the problem. as anex i send the subvi.

[Hooovahh]

I've never used an express VI but I assume it is creating and then closing the task every time you are in that loop.  Instead open a reference outside the loop, read it in the loop, then close it outside the loop. There going to be some time needed to open and close the reference but you only call it once instead of once every 200ms.  The write to file is probably doing the same thing where it opens then closes all the time.  Just like the DAQ call open once, write in the loop, then close once.  This should help your time.

[asnaev]

That would work... but :). i am adquiring a freq channel from other daq on sample by request too and one daq must close for the other to open. That solution is not viable.