Poorman's Space Program

Using the Vernier LabPro in a BalloonSat (Part 1)

L. Paul Verhage

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As a part of my Ph.D. in Education program, I developed a lesson plan to use Vernier dataloggers in a BalloonSat inquiry lesson. The specific datalogger we used was the LabPro, one of several types of dataloggers Vernier sells. Most of the students this lesson plan was written for have never used the LabPro before. Therefore, it was important for me to develop instructions showing how to use the LabPro.

Figure 1. Vernier's LabPro data logger.

LabPro ia a $200 datalogger with multiple options for displaying data. Typically, students connect the LabPro to a PC and records data right at their lab bench. However, students can also program the LabPro to record data remotely. Once collected, data can be downloaded into a PC, TI graphing calculator, Vernier stand-alone unit, or Palm handheld.

The LabPro’s analog to digital conversion process allows you to record up to 50,000 readings per second with 12 bits of resolution A resolution of 12 bits divides the maximum voltage reading into 4,096 pieces. If the maximum voltage the LabPro can measure is 5 volts (at the time I’m writing this article, I haven’t found the maximum voltage it can safely handle), then the LabPro can distinguish voltages at a granularity of 5volts/4,096 readings, or 1.22 millivolts.

The internal memory of the LabPro allows it to record 12,000 voltage readings. The 21.5 cm tall unit weighs 373 grams, and it can record data from four analog voltage sensors simultaneously. Along with its four analog channels, it also has two digital channels that will record on/off events like the tripping of photogates or radiation detection. If you are taking a science class in high school or perhaps in a community college, you’re probably using a Vernier datalogger.

Figure 2. The four analog ports of the LabPro.

Figure 3. The two digital ports of the LabPro.

I wrote the following procedure for Dr. Ellis’ CT442 class at the University of Kansas (Rock, Chalk, Jayhawk!!). If you plan to do us a LabPro in a similar remote datalogging application, like a BalloonSat, practice running through the procedure so you’re prepared to follow it on the morning of the mission.

Preparing a LabPro for a Near Space Mission

1. Verify there are good batteries in the LabPro (four “AA” cells).

2. Connect a Vernier serial cable to the PC.

Figure 4. A LabPro Serial Cable

3. Slide the LabPro computer connection window to the left to reveal the serial port
Plug the round DIN connector of the serial cable into the LabPro.

Figure 5. A LabPros’ serial/USB port. Slide the cover to the left (as shown here) to reveal the serial port.

Figure 6. A serial cable plugged into the serial port of the LabPro. If the cover is slid to the right, the USB port is exposed.

Start up Logger Pro

With the LabPro, either:

1. Plug an analog sensor (like temperature or UVA) into one of the analog ports on the left side of the LabPro.

(or)

2. Plug a digital sensor (like the Geiger counter) into one of the digital ports on the right side of the LabPro.

Figure 7. An analog sensor plugged into analog port channel 1.

Next, in the Logger Pro software:

1. Click File

2. Click NEW

Note: If Logger Pro recognizes the sensor, then click the Ignore/Erase Data LabPro button.

Figure 8. Select Ignore/Erase because we don’t need the data from the last time the LabPro was used.

The window in the bottom right of the screen should display current data from the sensor plugged into the LabPro.

Figure 9. The current data from the sensor is displayed as large red text.

Note: If Logger Pro doesn’t recognize the sensor, then the window displays only the voltage from the sensor. You need to either upgrade the version of Logger Pro or copy the experiment file for that particular sensor to the PC.

More on Vernier Dataloggers

You can discover the wide world of Vernier dataloggers at their web site, http://www.vernier.com/. Next month I’ll begin discussing several LabPro sensors and how to build a BalloonSat around the LabPro.

Onwards and Upwards,

Your Near Space Guide

A full list of all of L. Paul Verhage's Poorman's Space Program projects in The Citizen Scientist accompanies this article. For a Near Space overview, see this PowerPoint presentation: Near Space Platforms For Amateur Space and Astronomy. To learn more about Paul and his balloon research, enter his name in the SAS Google search window. Editor.

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The Citizen Scientist (01 January 2010.)