Unknown signal at start of signal generation

[ianhaigh]

Hi,

I'm working on a system to generate a sine wave to a hydraulic actuator, and then measure the displacement at various frequencies.

The problem I'm having is that Labview seems to be generating about 10 seconds worth of data that it has not been told to before it starts to generate the sine wave signal I want to produce from when I start to run it.

I've attached the VI and a screenshot on the unknown signal. If anyone could suggest where this is coming from I would be very grateful.

Many thanks,

Ian

[ianhaigh]

Also, I forgot to mention that when the frequency is altered, it takes the rig about 8 seconds to respond. I can't figure out where this delay is coming from either.

Ian

[TCPlomp]

You should look up the term Dataflow, this is the main source of your error.., do a  search on this forum and you will find many examples

You can also try searching this site and google for LabVIEW tutorials. Here, here, here, here and here are a few you can start with and here are some tutorial videos. You can also contact your local NI office and join one of their courses.
In addition, I suggest you read the LabVIEW style guide and the LabVIEW user manual (Help>>Search the LabVIEW Bookshelf).

Ton

[ianhaigh]

Thanks Ton,

I'd like to think I'm passed the tutorial stage, but the Development Guidelines certainly taught me a few things.

Thanks also for the pointer on Data Flow - I think I've figured out the source of the delay, even if I havent been able to fix it yet.

Cheers again,

Ian

[TCPlomp]

Your code looks like you are doing some unit/device under test (eg putting a signal through an external device)
In order to say anything useful about the reaction, you need synchronization. Look under LabVIEW help for multi funtion synchronization under the daqmx examples...

Also get as soon as possible rid of express vi's (that's a personal opinion)

Ton