Remote Temperature Monitoring with Linux

Digital multimeters are general-purpose electronic measurement tools. Although I used a thermistor for temperature measurement in this application, you can use other sensors that have resistance, voltage or electrical current as outputs. Some other conditions to measure include flow, pressure, weight, light level and humidity.

You don't need more multimeters to measure more than one temperature. You can connect a single multimeter to a switching device. You then would create a script to operate the switching device, which allows you to select one temperature sensor at a time.

This example shows how the tool concept behind Linux works for solving applications where cost and flexibility requirements are important. The wide variety of distributions available compared with other operating systems meant developing a system with all the features needed was practical. Additionally, you can add features using Perl and the development environment provided by the University Linux distribution.

The system can be duplicated for less than $100 US. The multimeter, thermistor and wiring accessories are available from numerous electronics retailers. Many retailers have Web sites, so it's easy to compare features, specs and pricing before ordering. Purchasing a used digital multimeter should be done with caution, as there is no easy way to tell whether accuracy of the instrument has been affected by the previous use.

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