I/O Solutions for Temperature Monitoring

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Sensors used for temperature monitoring and data acquisition can be quite varied. Applications ranging from simple room temperature monitoring to highly sophisticated batch process control can all be highly dependent on obtaining accurate temperature readings. The primary types of sensors used for this purpose are resistance temperature detectors (RTDs), thermocouples, integrated circuit temperature detectors (ICTDs), thermistors, and infrared sensors.

RTDs determine changes in the electrical resistance of materials in relation to temperature. RTDs deliver very precise readings (typically to 2–3 decimal places) and are manufactured in a variety of form factors. Though they are sometimes composed of nickel, copper, or other metals, historically, RTDs have been made of platinum--largely due to the fact that platinum's resistance-temperature relationship is maintained in a very linear fashion across very broad temperature ranges. RTDs' platinum composition also makes them somewhat expensive and unsuitable for applications involving temperatures above 660 °C, as temperatures above this range compromise the inertness of the platinum and may cause it to become contaminated and deliver inaccurate readings.

This white paper describes various temperature sensors such as RTDs, thermocouples, ICTDs, thermistors, and infrared sensors, and the Opto 22 solutions for using them.