cDAQ Chassis buffered non-regeneration analog output too slow

[Byeong-uk]

Hi there,

I am configuring a real-time closed-loop control software using cDAQ chassis with AI and AO modules.

The purpose of the program is simple.

 - Establish a hardware timed sampling tasks that collects data, process it, and write the signals. 

My devices are: cDAQ-9179 (14 chassis, with usb 3.0 ready), NI-9223 AI, NI-9262 AO

I purchased those cDAQ modules to use broader channels, and they are looking so fancy as well.., and it gives me a feeling that they might less susceptible to noise compared to other types. 

I expected that these cDAQ series will work as good as the M series usb devices where they have shown almost 99% satisfactory performances to my applications (it needs >1800 Hz loop rate). I was using AO non-regeneration mode and it gave almost 1,800Hz update speed w/o extra latency. 

However, when I test the cDAQ using the attached vi they were too slow (OMG 😱). 

For individual reads and writes, the analog input is fast enough.

However, the analog output is too slow on the regeneration mode. The problem is that I have to use the regeneration mode to make asynchronous generations. 

Please refer to the test vi program if there are any mistakes or suggestions. 

I was stuck on this problem about 1 month. 

I would not happy to buy cRIO series, for the NI devices take tooooo long time to get. 

I believe it is a software problem.. or I would buy another embedded board such as ARM to use RTOS porting.

Please help me!!