PXI-5402 to PXI-4498 Synchronizing

Question

I have a PXI-1033 Chassis with a PXI-5402 function generator in slot 2 and a PXI-4498 16 channel simultaneous DAQ in slot 3. I'm controlling in with Labview 2011 64bit though a ExpressCard-8360. I'd like to synchronize it so that DAQ starts collecting data an even number of cycles after my function generator starts.
Ideally it would work like this:
1. Start Function Generator
2. Wait a specified amount of time for the mechanical system to settle
3. Wait until the next cycle of the output from the function generator starts.
4. Gather the required data from the DAQ.
I'd like steps 3 and 4 above to happen with as little delay as possible. Currently I'm doing it like this:
1. Init Function Generator
2. Configure reference clock to PXI_Clock, this is the chassis internal 10Mhz clock
3. Route the front panel Sync_Out to PXI_Trigger Line 0
4. Init the DAQ and create the AI virtual channel
5. Configure the reference clock to PXI_Clk10, this is the chassis internal 10Mhz clock.
         I believe that I now have the all the 10Mhz clocks PLL together. Am I correct?
6. Set to True the DAQmx Channel Property AI.RemoveFilterDelay
7. Start the function generator
8. Wait the specified amount of time
9. Setup the sample clock on the DAQ
10. Set the DAQ to trigger on the rising edge of PXI_Trigger Line 0
11. Use DAQmx Control Task to commit these settings
12. Start the Task
13. Read the samples with DAQmx Read
This seems to work well except that I can tell from my data that it takes several 'tick' of the sample clock from the time the trigger fires until the first sample is actually read. Is there a way to reduce or compensate for this time?
Thinga that don't seem possible due to the limitations of the hardware:
Using Sync Triggers are not possible because they are not available on the function generator.
Using the Tclk function since it can't be used with DAQmx
Using the the Start Trigger and setting the AI Delay Time (or whatever it's called) to delay the start of data acquisition since it has the same problems   with trigger delay as the sync out
Setting the DAQ to slave because you cannot set the Function generator to Master.
So, finally, is there a better way to do this synchronization that will more closely tie the receipt of the trigger and the beginning of data acquisition?
I've also thought I could use a reference trigger and acquire the necessary number of pretrigger samples but I don't know if it's possible to get the trigger delay time through one of the property nodes. Is there a property node for trigger delay?

Answer 1

Hi Ben Manthey,
By using the dummy read before your actual read gives you the option of how many samples you throw out. The AI.RemoveFilterDelay property node only gets rid of a constant number and you are unable to change that. It seemed like the first couple samples you got were after the zero line and with the dummy read you can control how many are erased and have your first sample right at zero line. In the following link the article discusses more about using the dummy read and its use: http://digital.ni.com/public.nsf/allkb/F989B25FF6CA55C386256CD20056E27D?OpenDocument. Also if you use the analog triggering, you do not have to worry about the extra samples and the following KnowledgeBase article discusses this: http://digital.ni.com/public.nsf/websearch/EA42429C0BF5510C86256DA9007876E3. I have also included the NI Dynamic Signal Acquisition User Manual to provide more information about the triggering of DSA devices: http://digital.ni.com/manuals.nsf/websearch/C7F1AE47873FDE428625773700589591.
Regards,
Tommy G.
Applications Engineer
National Instruments