How to generate Digital Pulse using PXI-6238

[SRAZA]

Dear All

                  I want to produce Digital pulse from PXI-6238 or PXI-6704 or PXI-6527 ( i have all these)  with DAQmx 8.7.1 in LabVIEW 7.1. when i configure a channel in any of the above cards using DAQ assistant with continuse pulse/samples or N pulse it generates error 200077

Error - 200077 occured on DAQ Assistant

Possible Reasons:

Requested value is not a supported value for this property.
The property value may be invalid because it conflicts with another property.

Property: SampTimingType
Requested value: Sample Clock
You Can Select: On Demand

i like to generate pulse  up to  10kHz or even lower

Plz guide me.

[RikkiTikkiTucker]

Hi SRAZA,

Can you give a little more insight on your issue?  Does this error always occur? Can you provide screenshots of your code to show your setup?  This will help the community take a deeper look into your issue!

Thanks!

[SRAZA]

Thanks a lot for looking at my problem.  When I chose N Samples or Continuous it generates a message after pressing OK “The task has currently an error....................". But works OK with 1 Samples (on demand).  As I have to generate 10 kHz digital pulse, should I use 1 sample option and loop it 10K times to get the 10 kHz pulse?  I have attached all the screen shots in PDF.

What is meant by 1sample? dose it mean on Pulse??

Thanking you once again Tucker

[RikkiTikkiTucker]

Hi SRAZA,

I see what you are saying.  It appears your card does not support a Continuous mode for Digital Output tasks.  By 1 sample on demand, this means that everytime your DAQ Assistant is called in LabVIEW, it will generate a single sample for your Digital Output Task.  I would recommend checking out the Digital - SW Timed Output.vi example in the NI Example Finder, this might be able to help you with your application.

Thanks!

[Dennis_Knutson]

The specs clearly state that you have software timed digital I/O. With this, you will be lucky to get 1kHz in single sample mode. Try using the counter. Try to not use the DAQ Assistant.

[SRAZA]

Thanks all of you for looking at my post.  Can any body tell me what is differance between 1Sample(on demand ) and  1Pulse (on demand). same for continuous and N .....

[LDob]

Hello SRAZA,

Does this help document have the information you are asking for? It shows how the N Samples, 1 Sample (On Demand), and Continuous Samples acquisition modes work for the Run Once and Run Continuously modes.

http://zone.ni.com/reference/en-XX/help/371268J-01/expresswb/acquiring_data/

Lauren

Applications Engineering

National Instruments

[SRAZA]

Dear Sir Thanks for posting. This page elobrates differecancy between 1 Sample , N and Continuous . But has not discussed Pulse ....  actully i am confussed with 1 sample and 1 pulse (demand) . My DAQ assistant give me option for 1 Sample not for 1 pulse. But on right bottom side of the DAQ assistant configuration in Help it is shown that 1 Pulse on demand is also there. My qestion is that since my HW dont have this 1pulse option so should i take 1 sample meaning for 1 pulse. in my project i need pulses..

thanks again

[Dennis_Knutson]

This is quite basic. A single sample (with digital I/O), is either a logic zero or logic one. A pulse is a signal with both so you would simply need two writes to output a pulse. The duration of each single sample is poorly controlled with software only timing as already stated. Is there a reason you don't want to use a counter output as opposed to a digital line?

[SRAZA]

Thanks a lot for this eloboration .  This mens that samples= 2 * Pulse(S) if i am right?  No i dont have any reason for using digiltal line. it was just due to lack  my knowlege at that time. now i am using Counter output.  But getting some problem . If  you can help me . I just posted at http://forums.ni.com/t5/Multifunction-DAQ/DAQ-Pulses-on-LabVIEW-Graph-Chart/m-p/3190426/highlight/fa...

.

Thanks once again.