internal device routes to two clock sources

[Analog_lab]

Hi John,

Thanks a lot for your reply. I am able to use now counter0 to clock DO. I changed my sample mode to "Finite sample".

Before, I was getting following error.

Measurements: Onboard device memory underflow. Because of system and/or bus-bandwidth limitations, the driver could not write data to the device fast enough to keep up with the device output rate.

Reduce your sample rate, alter the data transfer method (from interrupts to DMA), use a product with more onboard memory, or reduce the number of programs your computer is executing concurrently.

Task Name: _unnamedTask<91>

I have attached my labview code. I am using  example program correlated dig write with counter.vi.

I have some question regarding the DAQ 6289.

1)  When I use Freqout as counter then I get an error saying Clock source not specified. I think, it does not recognize dev1\freqoutput terminal as clock source. I am mistaking in naming convention.

Error -89120 occurred at DAQmx Write (Digital 1D U32 1Chan NSamp).vi:1

Possible reason(s):

Source terminal to be routed could not be found on the device.

Make sure the terminal name is valid for the specified device. Refer to Measurement & Automation Explorer for valid terminal names.

Property: SampClk.Src
Property: SampClk.ActiveEdge
Source Device: Dev1
Source Terminal: freqoutput

Task Name: _unnamedTask<93>

2) As you mentioned about 80Mhz time base and division factor. Is there anyway I can control selection of timebase and division factor for counter in labview?

I have very little knowledge on daq card.

Thanks,

[John_P1]

Thanks for the extra info!  To answer your numbered questions:

1) The correct name for the internal output of the Frequency Generator (depending on your device name) would be something like: /Dev1/FrequencyOutput

2) DAQmx will choose the appropriate timebase for you so there shouldn't be a need to manually select the 80 MHz timebase.  If you wanted to do so, you could change the instance of the Create Channel vi to CO Pulse Ticks and specify the 80 MHz timebase as the source of ticks (4 ticks high and 4 ticks low would give a 10 MHz output with 50% duty cycle):

The error you are receiving (onboard device memory underflow) is a symptom of not being able to transfer data quickly enough from your PC's memory to the FIFO on the USB device.  The 1 MHz limit that you mentioned earlier is actually the maximum rate you can stream data continuously to the USB device (due to the high latency inherent to USB transfers) and doesn't have anything to do with the max frequency of the counter outputs:

The on-board FIFO is 2,047 samples for DO, so if you would like to continuously regenerate a waveform that is 2047 samples or less at the full 10 MHz then you may do so by enabling the following property node on your DO task:

I hope this helps, let us know if you have any questions!

Best Regards,

[Analog_lab]

Thanks John for yore help.