FX3U-4AD-PT-ADP Power module
Key Facts

• Input Type: 4 channels for 3-wire Pt100 temperature sensors.
• Resolution: Provides accurate temperature readings down to 0.1°C.
• Power Supply: Requires an external 24V DC power supply connected to the terminal block, alongside internal logic power (5V DC) drawn from the main PLC base unit.
• Connection: Attaches directly to the left side of the PLC CPU or other special adapter modules. 

How It WorksA Pt100 sensor is a metal wire that changes its electrical resistance based on heat. The module measures this small resistance and converts it into a digital number the PLC can understand. For example, if you place a Pt100 sensor in water, the module reads the sensor's current resistance. It then sends that data to the PLC. You can scale these digital values directly in your programming software (like GX Works2) to display the exact temperature in degrees Celsius or Fahrenheit