Compact-DAQ NI 9178 External Master Clock

[DaveG-GJ]

I want to use a 10 MHz GPS stabilized external clock as the master clock for a cDAQ system containing a Digital Output module and several Analog Input modules.  The external signal is a sine wave about 1 volt peak to peak.  I can plug the signal into the PFI0 (or PFI1) BNC connectors on the 9178 chassis and I would like to simply use the 10 MHz signal as the master clock for both DO functions and AI functions.  

The 10MHz sine wave needs to be "deglitched" so it provides a clean clock signal.  It seems I might be able to use the AnalogComparisonEvent to reliably detect each cycle of the 10MHz sine wave and to then route that event as the Master Timebase in the 9178 chassis.  But I have been unsuccessful so far.  Can someone tell me if this is possible or whether I must follow some other path such as using a counter or whatever?  Programming in .Net with DAQmx.  Thanks.

P.S.  I am hoping I don't have to build a separate small circuit just to square up the sine wave, and that I can indeed use an external clock to simply replace the internal clock and that I can tell DAQmx that the external clock is 10MHz.

[keroba]

Hi Dave,

Why do not you use the internal clock of your cDAQ? It is capable to give to modules a 10 MHz clock. If your are using LabVIEW  you just have to set the colck properties in the DAQmx timing.vi. You can see some LabVIEW  examples in help>>find examples>>Hardware input and output>>DAQmx>>Analog input (and select the example that adjust to your application) and/or Digital output (and select the example that adjust to your application)

Regards 

[DaveG-GJ]

Thanks for the reply.  The external clock is supplied by a GPS receiver that synchronizers a clock with Universal Time.  The clock is also derived from an oven controlled oscillator so that GPS outages can be handled with minimal drift.  The internal clock of the cDAQ is far too innacurate and far too unstable to remain synchronized with UTC over our planned measurements times.    

NI offers the NI 9467 module which does the same thing.  But it is only available in cRIO (==> LabView FPGA programming) and it must be used with LabView TimeKeeper (cRIO again).  cRio is significantly more expensive than cDaq.   And I do NOT use Labview and never will -- I find Windows .Net development with DAQmx far more efficient than LabView.

[keroba]

Ok  I see.

I think  that the only way here is to make the circuit to transform the sine wave to a square wave.

Best Regards