delay problem

[baller]

hi all,

I would like to know if it is possible to have a microsecond delay instead of the standards millisecond delay, because  i need more accurate delays in a for loop.

[jasonhill]

I think what you need is a timed loop.  You may need to look at using an RT target for very high precision delays.
http://zone.ni.com/reference/en-XX/help/371361A-01/lvdialog/loop_configuration_db/

[baller]

would this mean that i would need to purchase the real time module or is there a way to get the delay in microseconds just by using the software.

thanks

[smercurio_fc]

This question gets asked at least once a month, it seems. You won't be able to get microsecond resolution unless you run on a real-time platform. This means hardware. You cannot get microsecond resolution just with software.

[Dynamik]

Hi Baller,

      Just out of curiosity, what are you doing in the loop?

Sometimes it's possible to restructure logic and/or exploit DAQ hardware capabilities to eliminate the need for such high-speed/precision software loop...

Cheers.

[Kevin_Price]

Just a slight clarification:

1. Even under Windows (or other non-RT operating systems I'd guess), you can configure a timed loop to cycle at sub-millisecond intervals if you generate a timing source with a DAQ board.  Think of this as your request for Windows to honor your timing needs. 

2. Windows will often try to meet your timing needs, but will NOT be 100% successful.  The timed loop can let you know if a loop starts late and you can respond as you see fit.  So while you can't count on Windows to regulate the timing intervals, you can do a pretty good job of measuring them.  This is sufficient for some apps.

3. Many times people want fast loop rates to try to set up a control loop for some physical device.  I'd caution you that the variability in loop interval times under Windows will be at least a HUGE problem to overcome, and more likely an impossible one.  If you have a fast-responding device that requires a sub-msec control loop, you should look into RT or perhaps a motion controller board.

-Kevin P.