Phase difference issues in Heterogeneous device configuration

[satishgn]

Hi,

In heterogeneous device configuration-4472 + 446X + 6653(optional), after Routing the appropriate SampleClkTimebase & SyncPulse signal from the master device to each of the Slave device's & after setting the maximum SyncPulseMinDelayToStart in the master device, I am now faced with the phase difference problem.

From the DAQmx API reference manual, I got that this is happening due to the filter delays in both the devices & we have to account for this in our software. Has anyone done this before.

Jack, Are you online. You were very helpful to me for my previous post. Could you please help me to resolve this issue also. Thanks.

Satish.

[Marni]

Hello Satish. Thank you for contacting National Instruments! To get rid of the phase delay, subtract the time difference caused by the filter in software. You can take the data from NI DAQmx Read and use Get Waveform Components.vi to access t0. Use the subtract VI to subtract off a constant double of the delay time. Then use Build Waveform.vi to add the modified t0. This should fix the delay. Please let me know if you have any questions. Hope this helps! Have a great day!

Marni S.
National Instruments

[satishgn]

Marni, Thanks for the reply. Unfortunately I am not using Labview & I don't have one.
I'm using DAQmx ANSI C library. Do you have any sample code as how to achieve the functionality of the VI you mentioned.

Satish.

[Marni]

Hello Satish. The solution that I gave before is unique to LabVIEW, not NI-DAQ. If you are using ANSI C, you won't have the same functionality that you get with LabVIEW. You are going to have to figure out how to implement a delay in reading the data. This delay will not come from NI-DAQ, it will come from the ANSI C functions. Have a great day!

Marni S.
National Instruments

[satishgn]

Hello Marni,

The Problem is fixed now. In the software I've accounted for the fiter delay difference between 4476 & 4462 by the discarding the delay difference in samples b/w the 2 cards from the 4462 measurement.

Thanks.
Satish.