Can I use a substitute for the Sample Clock?

[programmindragon]

I have three different analog inputs coming from one device (PCI-6221).  Two inputs are running at the same sample rate while the third needs a faster sample rate and a trigger.  I have these seperated as two seperate tasks but my problem is they both use the sample clock.  Can I use a substitute for the sample clock on the third channel?

I am running LabVIEW 8.2 on Windows XP.

Thanks in advance for your help.

[dansch]

Hi programmindragon,

I understand you are trying to configure your PCI-6221 to sample on multiple channels, while having different rates and triggers for the channels. Unfortunately, you can only configure one analog input task to run at once and all the channels in the task must share the same configurations, including the sample clock and trigger. This is due to the fact that all the channels are multiplexed to a single amplifier and ADC on the device. Thus, you will not be able to configure the two inputs at one rate and use a different clock rate and trigger for the third input. Is it possible to sample at the maximum rate on all channels and decimate the data that you don't need on the certain channels, as well as share the same type of triggering? Hopefully you will be able to run your application with the same configuration across multiple channels, otherwise you may need multiple DAQ devices. Please let me know if you have any further questions related to this issue.

Regards,

[programmindragon]

Thank you for your response Dan.  I ended up sampling all channels at the maximum rate which helps more than hinders by giving me better resolution on the remaining signals.  Thank you for explaining why I wasn't able to get multiple analog signals at different rates.