PCI 6731 DO Clock

[waterland]

 NI PCI 6731 use as digital output.

 In Visual C++, I have an array of byte value (usigned int)  to output through port0.  I would like to use the internal sample clock to update the DO lines at rate of 1000Hz.  The function is called in the following way:

DAQmxCfgSampClkTiming(taskHandle, "OnboardClk", 1000.0, DAQmx_Val_rising, DAQmx_Val_Contsamps, 1000);

The error returned shows:   External Sample Clock must be specified for this application.

How do I use the internal clock?

[wildcat_600]

Hello waterland,

The reason that you are seeing this error is because the PCI-6731 uses correlated digital I/O and therefore has no dedicated clock source for digital output.  You need to specify a different clock source instead of just OnboardClk. 

There are a few pages in the help file that will explain this in more detail and also what other clock sources you can use.  You can find the help file at this location:  Analog Output Series Help. In the help file browse to Contents Tab >> Digital I/O >> Digital Waveform Generation.  This page will have a link to the possible clock sources that you can use. 

If you have any other questions please let me know.

Have a great day,

Brian P.
Applications Engineer