USB-6218 as an Oscilloscope

[dans]

Hi,

I am looking to setup a simple Oscilloscope using the USB-6218 DAQ.

I found the attached example but have not had any luck getting it to work. Just can't seem to see a signal.

I can't figure out how to alter the channel properties within the VI so that it matches my setup?

I am inputting a square wave on ai1 RSE.

What trigger arrangements do I need to setup???

Any tips appreciated.

Regards,

Dan

[gwd]

1. Does the hardware work when tested with measurement and automation explorer?

2. Are there any error messages?

[dans]

Hi,

Yep, the hardware is all working.

I have setup a simple DAQ Assistant to grab a channel and display it continuously on an Express Graph, and this is all working fine, with the signal visible as expected.

No error messages on the scope, just no signal visible.

I can't get my head around how the data acquisition is setup in Scope example?
Any tips?

Cheers,

Dan

[gwd]

Have you tried it with trigger at "none" (free-running??)

[dans]

Yep, has the trigger set to none.

Have now found the problem. The DAQmx create Channel within the waveread.vi is set to type default, which seems tomean Differential, whereas I had my signal Single Ended. So I think it was just floating off on the scope. Putting a differential signal in got it to work.

However, I can't seem to change the DAQmx Create Channel to an RSE value, without it reverting. How does this work?

Think I am going to look at the workings of this one and then use DAQ Assistant to create a Scope from Scratch!!! All Advice welcome!!

Thanks for the help.

Cheers,

Dan

[stilly32]

Hey Dans,

If you dig inside 2ch scope acquire>>wave read.vi, you can add a constant to the DAQmx Create Channel and change it from default to RSE. Like so:

Hope this helps,

Andrew S

Message Edited by stilly32 on 04-04-2007 05:53 PM

Message Edited by stilly32 on 04-04-2007 05:53 PM

[dans]

Thanks Andrew, did find that eventually, just missed the input because of the naming I think.

Cheers,

Dan