OM-USB-TEMP-AI User's Guide
Functional Details
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Once the resistance value is calculated, the value is linearized in order to convert it to a temperature value. The
measurement is returned by software as a 32-bit floating point value in a voltage, resistance or temperature
format.
Data linearization
An on-board microcontroller automatically performs linearization on RTD and thermistor measurements.
RTD measurements are linearized using a Callendar-Van Dusen coefficients algorithm (you select DIN,
SAMA, or ITS-90).
Thermistor measurements are linearized using a Steinhart-Hart linearization algorithm (you supply the
coefficients from the sensor manufacturer's data sheet).
USB connector
The USB connector pr5V power and communication. No external power supply is required.
LED
The LED indicates the communication status of the OM-USB-TEMP-AI. It uses up to 5 mA of current. The
table below defines the function of the OM-USB-TEMP-AI LED.
LED Illumination
LED
Illumination
Indication
Steady green
The OM-USB-TEMP-AI is connected to a computer or external USB hub.
Pulsing green
Data is being transferred.
Upon connection, the LED should flash three times and then remain lit (indicates a successful
installation).
Power
The
+5V
terminal is isolated (500 VDC) from the USB +5V.
Caution!
The +5V terminal is an output terminal. Do not connect to an external power supply or you may
damage the OM-USB-TEMP-AI and possibly the computer.
