Is there any way to specify the output update rate of a DAQ Assistant freaquency task?

[Aleksi-]

Hello.

I need to measure freaquency of a digital pulse counter in LabVIEW. I know that this is possible with DAQ assistant and I already tried it and it works.

The problem is this: The DAQ Assistant freaquency output seems to be updating only once in ~1s which is even nearly the rate that I need for this application. Is there any way to increase this output rate for freaquency measurement?

All help is appriciated!

[crossrulz]

What is the frequency range you are trying to measure?  What DAQ module are you using to measure this?

[Aleksi-]

I'm using NI USB 6353. The freaquency range is about 0-140000Hz.

Edit. 140 000, not 14 000.

[Aleksi-]

Any ideas on how to make the DAQ Assitant output update rate higher?

Help is greatly appreciated.

[GerdW]

Hi Aleksi,

when you want to control all DAQmx settings you should not use ExpressVIs…

Why don't you use basic DAQmx functions?

[Aleksi-]

I've checked some basic block -ipmplementations of a basic digital freaquency measurement but I still haven't come up with a way to adjust the update rate of the output.

[Aleksi-]

I still haven't come up with a solution to this problem. What actually is the core reason for the update rate being so slow and how can I change that?

Edit.

To be more precise I am using "one sample on demand" for the counting and the DAQ Assistant is inside a for-loop.

Thank you.

[ongeelim]

Hi Aleksi,

As what GerdW mentioned, its best to use basic (or low level) DAQ functions for configuration.

Anyhow, can you post a screenshot of the configuration of the DAQ Assistant?

Also, did you place any timing functions (like Wait, or Wait Until Next ms Multiple function) in the While For Loop?

-Ee Lim-

[Aleksi-]

I know but I'm a rookie so I have been trying to avoid using them.  I quess I should give it a try.

Anyhow you can see the Daq Assistant settings attached. And yes, I am using a Delay function inside the for loop (0,01s). I quess that's a problem? I do need it so I must come up with something else I quess.

Thanks for your help.

Edit. I haven't touched any of the settings that are not visible in the picture.

[ongeelim]

Hi Aleksi,

Well, you don't have to worry about building basic DAQ functions from scatch. There is already an example code in LabVIEW, where the codes for frequency measurement are already done for you.

All you need is to go to Help > Find Example, and look for the following example VI as shown in the diagram below:

I'm still trying to figure out the reason why the response is slow using DAQ Assistant.

-Ee Lim-