DAQ Assistant buffer error

[mahe3173]

 

  

 I have a program shown above, whose output i want to send to an oscilloscope through daq assistant. when i connect the array/waveform to daqassist, LabVIEW adds a convert to dynamic data express, whose output is also shown. But I get a buffer error for the daq assistant, what settings should I use to fix this. PLEASE HELP. p.s. I know my program is also inefficient, tips to make it better is also appreciated, thank you.

[GerdW]

Hi mahe,

---

@mahe3173 wrote:

when i connect the array/waveform to daqassist, LabVIEW adds a convert to dynamic data express, whose output is also shown. But I get a buffer error for the daq assistant, what settings should I use to fix this.

I know my program is also inefficient, tips to make it better is also appreciated, thank you.

---

Your VI is very inefficient: to make it better you should read this and use plain DAQmx functions!

I would read the error message as "you write new samples too often"…

• Why do you need a shift register and two controls to set the number of iterations of your FOR loop?
• Why do you need to calculate sin(pi/2) so often? Why not use an InitArray function with a "1" as input?
• Why do you need 4 charts/graphs to display the same data array?
• Which sample rate do you set/want to use?
• Why don't you use real waveforms with sample timing included?
• Which hardware do you use?
• Why don't you attach your VI?

(When attaching code from recent LabVIEW versions please downconvert: File->Save for previous. Most recommend LV2021 or older, I prefer LV2019.)

[mahe3173]

Thank you so much for the insights. 

• Im using 4 charts so that i can see what the convert to dynamic data had done to my input array. 
• Im not using the direct waveform functions, as I can't figure a way to multiple the Blackman window to every pulse of the sine wave separately.
• I have a PXIE-6363 and scb-68a to output the waveform.
• I'm not sure I understand your question of which sample rate i want to use.
• also i have never used the plain daqmx functions and am in a time constraint to understand how they really work, sorry.

my issue is that I don't understand how to output a set of values in an array through daq assist. so far I've only sent out waveforms generated by the simulate signal. Ive attached the LV 2019 file below. Thank you!

[GerdW]

Hi mahe,

---

@mahe3173 wrote:

• I'm not sure I understand your question of which sample rate i want to use.

---

In the DAQAssistent you activated the checkmark to use the timing of the waveform signal, but you don't provide a waveform in your VI. All you create is an array of samples, with no timing information! The DAQAssistent most probably handles your array as a waveform using a dt of 1, so it outputs the samples at 1Hz…

What is the desired sample rate in your application?

When you create 20 samples per iteration: how long should it take to "play" those samples over the AO channel?

Again: using DAQmx functions and waveform wires is much simpler than understanding DDT wires and what they do to your data!