I got a problem in using DAQmx. The NI I use is NI9265 (current generator) with cDAQ 9181 chassis (ethernet connection).
Now I'd use all 4 channels of 9265 to generate 2 current signals and 2 frequency signals to inject them into an equipment
which has a web interface that allows me to read the signal input (the 4 signals from NI). My problem is with my code the generated
signals are successfully read on the web interface, but if I change the values of any of the input signal, it takes more than 10s
for me to read on the web interface. This delay, after some search, shall be caused by buffering. I would like to ask with my code below
(based on an existed example), how can I minimize the delay?
(I tried to change the values of sample rate and number of samples, but made little difference, and beyond a limit, the code will fail to run).
di you notice this behaviour even on Front Panel, without using any web interface? Are you using web services or Remote Front Panel? Did you try to read generated signals with an oscilloscope?
Did you try to look at NI Example Finder in order to develop a simpler code?
That's good idea to do such check. From what I saw, in front panel I could read the generated waveforms in waveform graph instantaneously when I change the input freq. And still with this program, I took off the DC current generation to see if there's any differenece with the frequency generation, but it showed no difference. (I mean it still took morn than 10s for the freq being shown on the web interface even without the generation of current).
I'm not using remote front panel, but using my labview program locally, I just read the generated signals from a web interface of the device who receives them from NI.
i have a simple example to generate just DC current for 2 channels, that it uses only DAQ assistence instead of DAQmx blocks. With this simple program I can see the intantaneous change of current on the web interface.
I haven't tried to use the oscilloscope to read frequencies cuz I need others' help. But from my supervisor, this program worked with almost no delay on
the USB chassis, nevertheless now our goal is to use this damn ethernet chassis.
And I'd like to ask if you have any examples regarding to generate frequency siganls dynamiclly (I can change the value during the running of the program) with NI9265 for me to try?
Thanks for the suggestions anyway.
In the program I attached I didn't use any sub VI. During my develping this program I just used some
example codes from example finding in labview. if you mean the simple frequency generation example
program, you can find it in Help - Find examples - hardware input and output - DAQmx - Analog generation -