Independant analog output on two channels?

[BenYL]

For an unusual application, we are trying to measure the time delay (~2msec) of the lower branch signal below by measuring the phase shift of the two analog outputs. However, it is not working because the merge block is waiting for both signals to arrive which effectively re-syncs the signals. I've tried to simply clone the Analog Output block, but Labview complains about that since the outputs are both on the same device. Anyone have a solution besides buying a second DAQ card?

Ben

[ShaunR]

Not quite sure what you are doing here.

You are merging the generated and the echo response analogue signals and then outputting the result to the AO device. So the merged signal cannot be constructed until it has received both signals. It will then output the result to the analogue output device.

Wire the output of the signal generator directly to the analogue out device (remove the merge) then merge the analogue in with the reponse waveform from your echo server. I'm assuming your analogue out is connected to your anolgue input so I'm not sure why you would do this since you don't need the analogue devices at all.

[Neville D]

What hardware are you using and how many DMA channels does it have? The cheaper cards only have 1 DMA channel which means AO chans cannot be used independantly even if software timed. Alsothe onboard FIFO is also shared, which means the the AO channels cannot be used independantly.

Neville.