Interworld Electronics

PT-104 Platinum Resistance Thermometer Data Logger

The PT-104 is a four channel temperature measuring device. It offers the ultimate in resolution (0.001 °C) and accuracy (0.01 °C) when used with PT100 sensors. It can also be used to measure resistance and voltage. Measures temperature, resistance and voltage High resolution and accuracy Can be accessed via a modem For use with PT100 and PT1000 sensors A wide range of PT-100 sensors are available for use with the PT-104, see below for more details.

Accuracy and Resolution

Although accurate temperature sensors are widely available, it has been difficult to take advantage of them due to errors caused by the measuring device. The PT104 however, is inherently accurate due to its novel design. Rather than relying on voltage references (which tend to be temperature sensitive) it uses 'reference' resistors which are extremely stable (low temperature co-efficient and drift). The exact value of each resistor is stored in a EEPROM to provide the ultimate in accuracy (yearly re-calibration is recommended). To achieve the 0.001 °C resolution a state of the art ADC is used that can resolve to better than 1 part in 16 million.

Temperature

The PT104 measures temperature using platinum resistance thermometers (PRTs). Both common industry standards (PT100 and PT1000) are supported. The unit is compatible with 2, 3 and 4 wire sensors (4 wire PT100 sensors are recommended for accurate measurements). More information on sensors can be found below.

Resistance

When measuring resistance, the unit uses a four-wire circuit to give the greatest possible accuracy.

Two resistance ranges are available (0 to 375 ohms and 0 to 10,000 ohms). The unit is calibrated for 0 to 375 ohms so this range should be used for accurate measurements.

Voltage

For voltage measurements, each input connector can be treated as a differential input with ground, or two single ended inputs. Both inputs must be zero volts or above, though it does not matter which input has the higher voltage.

Two voltage ranges are available (0 to 115mV and 0 to 2500mV). For accurate measurements use the 0 to 2500mV range.

Software

The PT-104 is supplied with PicoLog software for advanced data logging. PicoLog will automatically detect which sensor is connected and will display readings in the correct units. For users who wish to write their own custom software, drivers and examples are supplied.

Remote Data Collection

The PT104 is normally connected directly to a PC, but it is also possible to communicate with the PT104 using a modem (radio or telephone) so that you can collect data from a remote site.

PT-104 Specification

PT100 Sensors

Platinum resistance thermometers (PRTs) offer excellent accuracy over a wide temperature range (from -200 to 850°C). Sensors are interchangeable between different manufacturers, and are available in various accuracy ratings and packages to suit most applications. Unlike thermocouples, it is not necessary to use special cables to connect to the sensor. (See our application note on choosing and using PT100 sensors for more information.)   Pico Technology supplies sensors (see below) that comply with BS1904 class B (DIN 43760): these sensors offer an accuracy of ±0.3 at 0°C. For increased accuracy we also supply tenth-DIN sensors (±0.03 at 0 °C). Specialist manufacturers can provide sensors with 0.001 at 0 °C accuracy (at a price). Please note that these accuracy specifications relate to the SENSOR ONLY. It is necessary to add the sensor error to the PT-104 error. An additional range of PT100 temperature sensors are available with a 7 to 10 day lead time. Click here for more information.

**IEC751:1983 Specifications

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