Clock Sharing Issues

[BadScientist]

Hi Folks,

I'm trying to utilize the onboard clock to both generate AO and analyze AI.  The vi's are attached.  The 2277 file generates 3 square wave pulses on three separate channels.  I'm trying to capture the combined return signals and measure the amplitudes of each pulse. 

My attempt to utilize the DAQmx export clock function on /dev1/PFI0 did not work.  I have read many of the posts and just don't understand what is going on.  I have a USB-6259 DAQ and LabView 7.1.

-Thanks for any assistance.  I will keep watching training videos.

[G_Lo]

Hi BadScientist,

I was able to run some test code using a simulated 6259 and exporting my clock to PFI0 and was not able to find any errors.  The 6259 specifications also state that this device has the ability to route your sample clock to PFI0.  If you are receiving errors, make sure to route signals within the same DAQ device.  It is a common mistake and very easy to make.  As a side note, you can also use the function called DAQmx Export Signal.vi in place of the property node to achieve the same functionality.  Once again, please elaborate on how the Export Function failed. 

[BadScientist]

G Lo,

Thanks for the reply.  I was able to get the output working onto PFI0 using the DAQmx Export Signal vi. 

Unfortunately, I am now stuck trying to use that as the input for the timing in the Cont Acq&Graph vi.  My first thought was to add a divider config vi to lower the rate.  However, I was unable to select the PFI0 as the source.  It will allow me only to select a counter.  Can I export the signal to the counter somehow or is there a better option.

-and I really appreciate the assistance.
 

[G_Lo]

BadScientist,

If you would like to divide the frequency of the signal that is input on PFI0 then you could utilize a counter for this.  This thread describes a method for this divide down.  You would need to specify the source of ticks as PFI0 and keep in mind that you can only divide down by an integer multiple of 4 or greater.  The divided clock can be accessed by selecting Ctr#InternalOutput as the clock source for your application.  For example, if you wish to use the divided clock for an analog output then the DAQmx Timing.vi (set as Sample Clock) for the analog output would have Ctr#InternalOutput as the source.  No external connections are necessary in this case.  Hope this helps! 

[BadScientist]

Thanks for the reply.  Unfortunately, I am still on LabView 7.1 and cannot open the vi.
Could you post a screen shot or save as previous revision?

Thanks!

[G_Lo]

BadScientist,

I have included a screenshot of the portion of code that will divide down your signal by an integer multiple > 4 and output the divided signal on Ctr#InternalOutput.