Date: Thu, 16 May 2002 12:14:27 -0500

Author: Tom Huber

Subject: Re: LabVIEW for LabPro? (was: LabVIEW Pricing? What to get?)

Post:

Paul,
We used LabPro's with LabVIEW to set and read analog voltages for some
labs a year ago (we wrote all of the drivers ourselves since the Vernier
ones were not yet widely released). Our drivers were fairly
specialized, so I am not sure if they would be of great value to post
them. One problem with the LabPro's is that they only support serial
(RS232) for anything other than their LoggerPro software. Talking to
David Vernier last year, it does not appear that they will be able to
support USB with LabVIEW. This limits the LabPro to about 2-3 samples
per second maximum in command/response mode.

For some experiments in our advanced lab course, we needed a faster
interface so we could read the input and control an output (from
LabVIEW). We also wanted a digital counter that we could read from the
program. We ended up purchasing a few LabJack interface units. (See
http://labjack.com for info). They are $99 each and have 4 12-bit
analog inputs (+/-10V), 4 digital inputs, 2 analog +/-10V outputs, and a
32 bit counter. They operate via USB and come with drivers for LabVIEW,
Visual Basic/C++, etc. We could take about 50 samples per second.
They worked very well as a counter and for most analog/digital input and
output.

The only concern that we had with them is that the input bias currents
for the analog inputs were on the order of 10-20 uA, so if they are
attached to a large resistor (>~100k) it can lead to a sizeable voltage.
Therefore you need to be a bit careful about what you attach them to
when making analog input measurements. On the whole, however, they
are a very nice unit (especially for the price) that are fairly easy to
use within LabVIEW.
Tom



Paul Nord wrote:

> Thanks for the many responses to my LabVIEW question. I hope to, someday,
> have budgets like yours.
>
> I downloaded the demo version and started playing around with the "LabVIEW
> for LabPro" Vi's from Vernier. They're pretty primitive. Anyone
> created a more robust Vi for the LabPro? Care to post them for common
> reference?
>
> Paul
>


--
Tom Huber, Physics Department, Gustavus Adolphus College, St. Peter, MN
Office: Olin 209 (507) 933-7036 FAX: (507) 933-6104
email: huber@gustavus.edu http://physics.gac.edu/~huber/

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