can 'Hardware timed single point 'sample mode with 'wait for next sample VI' in DAQmx provide real time control?

[vks]

hi

i am working on concept of realtime control and pc based control using LV2012 with PCI 6221 and cFP.i just wanna know can ' 'Hardware timed single point 'sample mode with 'wait for next sample VI'in DAQmx provide real time control?it is given in NI's whitepaper that these functions/VI s are used for deterministic tasks on real time platform.if it is so then what is the need for real time platforms like cFP for real time control.

kindly clear the ambiguity...

vks

[crossrulz]

Because Windows is not a deterministic OS.  The OS likes to steal clock cycles for various things like update the display, let other services run, etc.  You cannnot guarantee that your loop will run at the rate you told it to.

A Real Time OS is different.  It will allow you loops to run at the rate they need to with very little jitter.

I have measured jitter on Windows to be in the tens of milliseconds.  The RT (like cFP) are supposed to have a jitter in the microseconds.  Jitter is a bad thing when it comes to control algorithms, so you need the determinism of an RT system.