Problem: Data input at twice the rate signal output

[Wali Akthar]

Hi,

I have been trying to figure out this problem for a while now.
I want to be able to output a multichannel signal and simultaneously acquire it back. The problem I have is that my output signal consists of two channels of data (2048points at 204.8Hz = 10 secs of data). These two channels consist of simple sine waves where channel 1 has 3 cycles and channel 2 has 5 cycles within 10 sec interval. Now when I output this and acquire it back I get channel 1 having 3 cycles and channel 2 having 5 cycles within 5 seconds whilst the rest (5-10secs) is zero!!
Something is out by a factor of 2 somewhere....but where !!
Another thing...if I was Rate = 204.8 then I get a status error for the function call SCAN_Start


-10697 rateNotSupportedError Unable to convert your timebase/interval pair to match the actual hardware capabilities of this board.

but if I use Rate=200 when calling DAQ_Rate before SCAN_Start then it works fine!!!


PLEASE HELP ME !!!!!

[Sastry V.]

Hi Wali,

This is happening because the DAQ_RATE seems to be selecting a timebase that is not supported by the E series card. As you know, you can use only 100KHz or 20MHz internal timebase with E series cards, so specify the timebase and interval yourself and see if it works.

Please do let me know what happens.

Sorry for the delay in posting the response.

Sincerely,
Sastry V.
Applications Engineer
National Instruments