The PT100 is a precision temperature sensing device that utilizes the predictable change in electrical resistance of platinum correlating to temperature. It is a Resistance Temperature Detector (RTD) with a nominal resistance of 100 ohms at 0°C. PT100 sensors are widely used in industrial and laboratory applications due to their high accuracy, long-term stability, and repeatability.
This circuit is a temperature control system that uses a thermocouple to measure temperature and a PID controller to regulate it. The PID controller drives a solid-state relay (SSR) to control an external load, with power supplied through an AC inlet socket.
Open Project in Cirkit Designer
This circuit is designed to measure temperature using a PT100 sensor interfaced with an Arduino Mega 2560 through an Adafruit MAX31865 RTD Sensor Breakout. The Arduino controls a relay based on the temperature threshold set via serial input and displays the temperature readings on an I2C LCD display. The relay can be used to control an external device, such as a heater or a fan, based on the temperature.
Open Project in Cirkit Designer
This circuit is a basic power control system that uses a rocker switch to control the flow of 220V power through a resettable fuse and a PT100 temperature sensor. The switch allows the user to turn the power on or off, while the fuse provides overcurrent protection and the PT100 sensor can be used for temperature monitoring.
Open Project in Cirkit Designer
This circuit uses an Arduino Nano to read temperature data from a MAX31865 thermocouple amplifier connected to a PT100 sensor, display the temperature on a round TFT screen, and log the data with timestamps using a DS3231 RTC. A momentary switch is used to control the logging and display a temperature graph on the TFT screen.
Open Project in Cirkit Designer| Pin Number | Description |
|---|---|
| 1 | RTD lead 1 |
| 2 | RTD lead 2 (optional) |
| 3 | RTD lead 3 (optional) |
Note: PT100 sensors can come in 2-wire, 3-wire, or 4-wire configurations. The table above shows a simplified 2-wire configuration.
Q: Can I use a PT100 sensor with an Arduino UNO? A: Yes, but you will need additional circuitry, such as an ADC with RTD support or an RTD-to-digital converter module.
Q: How often should I calibrate my PT100 sensor? A: Calibration frequency depends on the usage conditions and required accuracy. It is typically recommended to calibrate annually or after any mechanical shock or exposure to extreme temperatures.
Q: What is the difference between a 2-wire and a 4-wire PT100? A: A 2-wire PT100 has the simplest configuration but is most susceptible to lead resistance errors. A 4-wire PT100 offers the best accuracy by completely eliminating the effect of lead resistance.
Below is an example of how to interface a PT100 sensor with an Arduino UNO using a MAX31865 RTD-to-digital converter module.
#include <SPI.h>
#include <Adafruit_MAX31865.h>
// Use software SPI: CS, DI, DO, CLK
Adafruit_MAX31865 max = Adafruit_MAX31865(10, 11, 12, 13);
// or use hardware SPI, just pass in the CS pin
//Adafruit_MAX31865 max = Adafruit_MAX31865(10);
void setup() {
Serial.begin(115200);
Serial.println("MAX31865 PT100 Sensor Test");
max.begin(MAX31865_3WIRE); // Set to 2WIRE or 4WIRE as needed
}
void loop() {
uint16_t rtd = max.readRTD();
Serial.print("RTD value: "); Serial.println(rtd);
float ratio = rtd;
ratio /= 32768;
Serial.print("Ratio = "); Serial.println(ratio, 8);
Serial.print("Resistance = "); Serial.println(RREF * ratio, 8);
Serial.print("Temperature = "); Serial.println(max.temperature(RNOMINAL, RREF));
// Check and print any faults
uint8_t fault = max.readFault();
if (fault) {
Serial.print("Fault 0x"); Serial.println(fault, HEX);
if (fault & MAX31865_FAULT_HIGHTHRESH) {
Serial.println("RTD High Threshold");
}
if (fault & MAX31865_FAULT_LOWTHRESH) {
Serial.println("RTD Low Threshold");
}
if (fault & MAX31865_FAULT_REFINLOW) {
Serial.println("REFIN- > 0.85 x Bias");
}
if (fault & MAX31865_FAULT_REFINHIGH) {
Serial.println("REFIN- < 0.85 x Bias - FORCE- open");
}
if (fault & MAX31865_FAULT_RTDINLOW) {
Serial.println("RTDIN- < 0.85 x Bias - FORCE- open");
}
if (fault & MAX31865_FAULT_OVUV) {
Serial.println("Under/Over voltage");
}
max.clearFault();
}
Serial.println();
delay(1000);
}
Note: The above code uses the Adafruit_MAX31865 library to interface with the MAX31865 module. Make sure to install the library before compiling the code. The RREF and RNOMINAL constants should be set according to your specific hardware setup.
This documentation provides a comprehensive guide to using the PT100 sensor. For further assistance, consult the manufacturer's datasheet and application notes.