Acquire external and internal clocked data simultaneously

[jam8c7]

 

Is it possible to use a shared start trigger to collect 6 channels of data using an internal clock source while simultaneously collecting data from another set of 2 channels using an external clock source using the same DAQ Board?  The specific board that I am using is a PCI-6259 and am programming in LabVIEW software. 

[Justin_M]

Hi jam8c7,

It depends on the type of channels you are using.  All the channels of the same type, say analog input, must share the same clock.  However, if the 6 internally clocked channels are analog input, and the 2 externally clocked channels are of a different type (correlated digital I/O, for example), then you can use different clocks.  What are the types of channels you are trying to use in your application?

Thanks,

Justin M.

National Instruments

[jam8c7]

 Thanks for your reply.  All the signals are analog at this time.  In my previous message I stated that I would like to internally clock 6 channels and externally clock 2 channels.  That is actually backwards, I would like externally clock 6 and internally clock 2.  One channel that I would like to internally clock is a microphone.  The current pre-amp I am using has an analog output.   Is there a problem with sending that signal to an A/D converter then acquiring it digitally?  Just to confirm, would I be able to use the same start trigger for both the digital and analog data acqusitions?  If this is the case then I would only need to acquire the one channel digitally. 

[Justin_M]

jam8c7,

You can clock the analog and digital lines differently.  However, the digital lines do not have their own internal clock source and cannot be configured for a trigger.  To get around this, you can actually trigger the timing source itself.  For example, you could set the DIO lines to be clocked off of the counter output, and then set up a trigger for that counter output.  The following example might help:

Performing Triggered Digital IO with an M Series Device in LabVIEW

Thanks,

Justin