Synchronized Digital output (internal clock) NI-6259

[Brian F.]

Hello. 
Thank you for posting to the NI Discussion Forums. 
What method are you using to output the digital signals?&nbsp; Are you using waveform generation so the outputs can be hardware timed?&nbsp; If so, I invite you to check out the M Series User Manual located at: M Series User Manual<a href="http://www.ni.com/pdf/manuals/371022g.pdf" target="_blank"> http://www.ni.com/pdf/manuals/371022g.pdf</a> I found pages starting at 6-5 very helpful.&nbsp; A few passages that may be helpful are:

"You can generate digital waveforms on the Port 0 DIO lines. The DO waveform generation FIFO stores the digital samples. M Series devices have a DMA controller dedicated to moving data from the system memory to the DO waveform generation FIFO. The DAQ device moves samples from the FIFO to the DIO terminals on each rising or falling edge of a clock signal, do/SampleClock. You can configure each DIO signal to be an input, a static output, or a digital waveform generation output."&nbsp; So, all digital signals will be moved to all lines of Port 0 at the same time if you provide all lines data.&nbsp; This also points out that do/SampleClock is the clock that controls this output.In regards to question 3, "Use the DO Sample Clock (do/SampleClock) signal to update the DO terminals with the next sample from the DO waveform generation FIFO.&nbsp; M Series devices do not have the ability to divide down a timebase to produce an internal DO Sample Clock for digital waveform generation.&nbsp; Therefore, you must route an external signal or one of many internal signals from another subsystem to be the DO Sample Clock."

Finally, refer to page 6-4 for an answer to question #2.&nbsp; If you wish to know how to program this in LabVIEW, I would invite you to look at our Example Finder.&nbsp; This can be accessed by clicking on Help&gt;&gt;Find Examples when on the Front Panel or Block Diagram.&nbsp; Here you will see a directory structure of examples.&nbsp; Please click on Hardware Input and Output&gt;&gt;DAQmx&gt;&gt;Digital Measurements or Digital Generation.&nbsp; There are a lot of great examples here that will help get you started.&nbsp; Let me know if there is anything else we can do for you.&nbsp; Have a great day!

Brian FApplications EngineerNational InstrumentsMessage Edited by Brian F. on 05-09-2007 08:51 AM

[Brian F.]

Hello.&nbsp;
&nbsp;
The reason that the error is occuring is that using the do/sampleclock as a trigger is not supported with M Series cards.&nbsp; Furthermore, this is unnecessary because this is the clock that controls when&nbsp;DO is performed whether or not a trigger is configured.&nbsp; So, in other words, if we have no triggering in our program, and output a digital signal, by default, we will use the do/sampleclock.&nbsp; By selecting the same signal as your sample clock source, you are in fact routing that signal to itself and this is not allowed.&nbsp;
&nbsp;
So, in order to sync digital outputs, you must use an external clock.&nbsp; There is no way to output sync'ed digital outputs without one.&nbsp;
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Brian FApplications EngineerNational InstrumentsMessage Edited by Brian F. on 05-10-2007 03:04 PM

[Brian F.]

Hello.&nbsp;
You are correct in your last statement: you must use an external clock.&nbsp; As far as DAQ cards that would support the internal clocking, the 653x series of cards can do this.&nbsp; These include the PCI-6533, PXI-6533, PXI-6534, PCI-6534, PCIe-6536, PCIe-6537.
&nbsp;
Brian FApplications EngineerNational Instruments