How do I make an Auto-ID Resistance Probe

LabPro, LabQuest, EasyLink, Go!Link, CBL 2 and the original CBL will all recognize an Auto-ID Resistance probe. No company has ever manufactured such a probe. It is however quite simple to create the hardware and adapt the software that controls your data collection.

##########     HARDWARE     ##########

Use the cable from an Analog Sensor Kit (CBL-ANK) or simply cut the cable from another sensor like TI-Light, TI-Voltage, etc. TI-Voltage is good because you can reuse the clips for your Resistance Probe.

Now it is a matter of connecting the proper conductors. Go to the following web page for details about the cable:
http://www.vernier.com/probes/specs/pinout.html

-1- Connect pin 3 (Vres) and pin 6(Vin-low). Add a clip of some kind to the end of this junction. Connect the resistance to be measured from the junction of these pins to pin 2 (Gnd).

-2- Connect a clip of some kind to the end of pin 2 (Gnd). If you want it to be an Auto-ID probe, connect a precision 3.3 kΩ resistor between pin 2 (Gnd) and pin 4 (AutoIDENT).

-3- Insulate pins 1 and 5 since they are not used.

Measurements are made between pin 2 (Gnd) and the junction of pin 3 and pin 6. The range of the sensor is 1 kΩ to 100 kΩ.

##########     SOFTWARE     ##########

++++++++++     Calculators     ++++++++++

*** DataMate (CBL 2 and LabPro) ***
Simply use DataMate and allow the sensor to Auto-ID.

*** EasyData (EasyLink, CBL2, LabPro) ***
Simply use EasyData and allow the sensor to Auto-ID.

*** With Original CBL ***
Vernier has no software to support this sensor with the original CBL. It is possible to write your own calculator program to collect data with this sensor and the CBL. Also, a properly made, Auto-ID Resistance Probe and an original CBL can be used to monitor resistance. Connect the probe to CH1 of the CBL, then press the MODE button on the CBL to enter Multimeter mode. Your sensors resistance readings will be displayed on the CBL screen.

++++++++++     Computers     ++++++++++

*** Logger Pro 3.x (with LabPro, LabQuest or Go!Link) ***
You will need to add a new sensor to the sensormap.xml file. This file is located in .../Vernier Software/Logger Pro 3/Support/sensormap.xml, (Windows,) or /Contents/Resources/sensormap.xml (Mac) in the application package. To get to the application package on Mac, ctrl-click on the Logger Pro application itself and select "Show Package Contents" then navigate to Contents/Resources.

-1- Close Logger Pro if it is running.

-2- Make a backup copy of the sensormap.xml file. Name it something like sensormap.xml.old.

-3- Open the sensomap.xml file with any text editing software.

-4- Copy the text in the attached file (sensormap_section.txt.)
Download the sensormap_section.txt using the link below:
http://www.vernier.com/til/files/1210/sensormap_section.txt

-5- Navigate all the way to the bottom of the sensormap.xml file and copy the text just above the file's closing tag that reads "SensorMap"

-6- Save the sensormap.xml file, then restart Logger Pro.

The next time you connect your Resistance Probe to your LabPro and start Logger Pro, the probe should be identified.

*** Logger Pro 2.x (with LabPro) ***
You will need to edit a file and create at least one new file in the following directory (or equivalent): .../Program Files/Vernier Software/Logger Pro (2.2)/Experiments/VSAutoID

-1- First open the file autoid.ini in a text editor and add the following lines:
[RES]
CHANNEL=4,0,0,0,0,0,0,0
FILE=RES.mbl

This instructs Logger Pro to open the file RES.mbl whenever it sees a Resistance Probe in CH1.

-2- Create the RES.mbl file. With your LabPro connected, start Logger Pro 2.x. Open a New file, set up a 0-5 Volt sensor in CH1 and change any of the other data collection parameters that you want to change (add a Meter Window, set the data collection rate, change the min and max of the Graph's Y axis, etc.)

-3- Go to Data:New Column:Formula. In the New Column Options Tab, enter a Long Name (Resistance), Short Name (Res) and Units (kOhm). You can also set the Significant Figures. Click the Definition tab to display the column's equation. In the equation line of this dialog type:
("Potential"*15)/(5-"Potential")
Click OK when you are done. This new, calculated column will turn the 0-5 Volt signal (Potential) into units of kΩ.

-4- Choose File:Save As and save the file in the above mentioned directory, with the filename RES.mbl

-5- Close Logger Pro. Browse the computer to locate the file you just created. Once found, right-click on the RES.mbl file and choose Properties. Mark this file as Read-only by checking the Read-only checkbox in the File Properties dialog.

Now the next time you start Logger Pro with an Auto-ID Resistance Probe in CH1 of LabPro, the RES.mbl file will be opened and you will be measuring resistance with your own custom-made Resistance Probe.

++++++++++     LabQuest     ++++++++++

LabQuest (v1.1) application does not have a simple way of adding support for the auto-id of the resistance probe. It is planned to be added in a future version.