error -200018 DAQ AI/AO

[TechnicRC]

Good morning folks,

I recently fused by sensor readings vi with this swept sine frequency reponse vi and came up with an issue.  My DAQmx write AO VI seems to be running a bit crazy and generates and error -200018  The problem occured when I added the DAQAssistant vi (for AI) in the same loop as the Analog Output VI.  I tried to decrease the rates/samples to very small values (50 samples at 50Hz) but with no success. 

I have been searching through the forum and have been running through a lot of documentation and have found that people have had similar issues to me with AO/AI running side by side and with no real solution.

ex: http://forums.ni.com/t5/Multifunction-DAQ/Error-200018-using-PCI-6259-and-Labview-8-5/td-p/851264/pa...

http://forums.ni.com/t5/Multifunction-DAQ/200040-AO-Error-on-CompactDAQ-changing-with-AI-channel/td-...

People have stated that they found a work around by adding a DAQmx Is Task Done.vi after the DAQmx Write VI or switching the AO from DMA to Interrupt, or using the onboard memory but none of those solutions worked.

However I have found documentation specifically pertaining to my error (-200018) which can be found here https://decibel.ni.com/content/docs/DOC-15893 in the attached continuous buffered generation pdf on page 13 but with no stated solution...  Hoepfully you can provide further assistance.  I would assume you would be able to have AI and AO running side by side but I may be mistaken..

Error -200018:

DAC conversion attempted before data to be converted was available.

Decrease the output frequency to increase the period between DAC conversions, or reduce the size of your output buffer in order to write data more often. If you are using an external clock, check your signal for the presence of noise or glitches.

Task Name: _unnamedTask<14EC>

I would appreciate your help.

Thanks

Robert

[TechnicRC]

So I have been doing more testing and have simplified/optimized my code below to a point where the only thing happening is a PWM singal being generated (based on the swept sine wave calculation) from an AO port on the NI 9264 module.  The code works great UNTIL I add the DAQAssistant VI and try to read a voltage measurement using the NI 9205 module.  No matter what setting I set the AI too (rate/samples) the code failed to work.  

Here is the Error: -200018

DAC conversion attempted before data to be converted was available.

Decrease the output frequency to increase the period between DAC conversions, or reduce the size of your output buffer in order to write data more often. If you are using an external clock, check your signal for the presence of noise or glitches.

Task Name: _unnamedTask<6A>

I have found articles stating that AI/AO can be achieved by sharing the AO output clock.  What do you guys think?  Is this the right direction or is there an easier way?  Here are some links detailing this approach.

https://decibel.ni.com/content/docs/DOC-26326

http://zone.ni.com/devzone/cda/epd/p/id/773

Your folks help would be really appreciated

Robert

[Eric-E]

Hello,

Are you able to run an continuous acquisition example from LabVIEW Help for AO on the 9264 and for AI on the 9205 at the same time?

Thanks,

Eric E.