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TR4 Thermistor Smart Interface

The TR4 is a digital interface to allow connection of thermistor temperature sensors to the SL5 Smart Logger. It provides a means of connecting up to four thermistors of the specified type to the system.

What is a thermistor?

A thermistor is a temperature sensing device whose resistance varies with temperature. The relationship is non-linear but offers greater accuracy and lower noise than a thermocouple type device when properly used. The TR-4 is factory calibrated to directly convert the resistance of the sensor to °C with great accuracy. However because there are many different types of thermistors available, the correct specification device must be used.

The TR4 is designed to work with a 10KΩ (nominal) NTC thermistor, RS151-237 or exact equivalent. This is a curve-matched device with an accuracy of ±0.2°C. No other type should be used. ICT can supply these thermistors, part number ICT151-237. The data sheet for this device is available here.

Digital Output

The TR4 is microprocessor-controlled so the conversion from analogue to digital signals and processing of raw resistance to engineering units is handled at the point of measurement. The digital serial output is compatible with the Smart Logger’s 3-wire Databus protocol and this allows the data to be transferred up to 4km without any loss in signal or degradation of data quality. The Smart Logger’s software interface provides the user with a simple to use menu via HyperTerminal.

Applications

The TR4 is an excellent multi-sensor device for any temperature measurement application. It is highly accurate, low cost and easy to use. The screw terminal connection of the TR4 Smart Interface allows easy and convenient access to swap or change thermistor sensors.