Why am I getting an error about units?

[MinerHokieRamp]

I have Labview 7 Express Student Edition on a Dell laptop with XP Pro. I was building a vi with the Simulate Signal Express vi, connecting pointer slides to the amplitude and frequency terminals. I got a broken wire and an error message on the frequency terminal; the error said 'units are incompatible'. There was no error or broken wire on the amplitude terminal.

On the slider, I tried showing units and typing in 'Hz'. This didn't help. How does one setup the units for amplitude and frequency...both at the slider and at the simulate signal express vi?

Thanks,

Jeff

[jpeters]

You could try using the Convert Unit primitive. This would remove the units from your slider. Wire the slider to the primitive then the output to the express VI. Good luck.

Jeff P

[MinerHokieRamp]

Thanks Jeff. According to the book that included the student edition cd, there is a demo vi that does what I want to do. I couldn't find it in the learning directory so I was trying to recreate it as shown in the book. The vi diagram in the book (about page 514) doesn't include the Convert Unit primitive.

I'm trying to come up with some audio demonstrations for an 8th grade class, illustrating wavelength measurement and constructive and destructive interference. I'd like to be able to connect a signal from the vi to the laptop's audio output jack. I've searched ni.com, looking for a way to both display a sine wave and play the tone in the speaker but no luck so far.

I might have to just create .wav files and play them. It sure would be fun to
be able to move the slider's pointer and let them hear the change in tone.

Thanks,

JeffreyP

[Ankita A.]

Hi Jeffrey,

I am not sure why you cannot connect two slide pointers to a Simulate Signal Express VI's Amplitude and Frequency terminals. Please try to do it again in a new VI. If you still have the same problem, please let me know and I will try to investigate the issue further.

As for the sound application, you might want to check
out LabVIEW shipping example Continuous Sound Output.vi and modify it based on your needs.

Regards,
Ankita A.
National Instruments

[jpeters]

This seems to be a bug in LabVIEW 7.x and has been reported to R&D via the proper channels.

Jeff Peters
LabVIEW R & D

[MinerHokieRamp]

You were able to duplicate the error?

JeffreyP

[jpeters]

Yes. I just attached a slider with units to the terminals stated.