Labview with cdaq PID-Controller refrashrate 1000 Hz to slow / Error -200279

[RubR]

Hello everyone, 

i want to build a PID-Controller with a cdaq and the labview software,

like in this Youtube video from National instruments channel:

https://www.youtube.com/watch?v=fkbt85mBzuM&list=PLB968815D7BB78F9C&index=12

My problem is, that i need a faster meassurement as shown in the video.

I need to refresh the labview aplication with 1000 Hz.

I can also increase the speed of the AnalogIn modul to this rate,

ans everything works fine.

But when i used the 9263 Analog Out Modul with the pid controller, 

than i reached not higher rates than 10 times per second refrashrate. 

If i increase it higher, than i get after some time Problems like "buffer overflow",

because the AnalogOut Modul seems to be to slow.

To enclose the problem:

I connected the DAQ Assistant manager from the AnalogIn modul

directly with another DAQ Assistant manager from the AnalogOut modul.

So i want to give the meassured voltage out, as fast as possible.

Settings:

Analogout DAQassistant: "1 sample (on demand)"

Analogin DAQAssistant " Continuous samples", samples to read: 10, rate: 1000 Hz

After some seconds, i get these error:

 ----------------------------------------------------------------------------------------------------

Possible reason(s):

The application is not able to keep up with the hardware acquisition.
Increasing the buffer size, reading the data more frequently, or specifying a fixed number of samples to read instead of reading all available samples might correct the problem.

Property: RelativeTo
Corresponding Value: Current Read Position

 ----------------------------------------------------------------------------------------------------

Could some tell me, what the problem is and how i can fixe it,

to get the necessari speed?

best regards 

Ruben Rodermann

[Kevin_Price]

You're not going to get a reliable 1000 Hz PID loop rate on a cDAQ system.  Using DAQ Assistants will limit you too.

Your 1000 Hz rate for AI is probably a sample rate that delivers data in good-sized chunks, leading to a PID loop rate noticeably less than 1000 Hz.  This is efficient for data transfer but it also *necessarily* adds latency which is typically troublesome for PID loops.

What are you controlling?  What kind of response bandwidth does your system have?

-Kevin P