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USB-DAQ-RD supports 2-channel PT-100/PT-1000 RTD temperature sensors, providing 15-bit resolution with temperature resolution of up to 0.03125°C and a total accuracy of 0.05%, suitable for high-precision temperature monitoring.

USB-DAQ-RD

Product Features​

  1. USB 2.0 Full Speed bus-powered
  2. 21-channel 3.3V Digital I/O (5V tolerant)
  3. Supports I2C/SPI/UART/PWM/Counter
  4. 2-channel RTD input
  5. Supports PT-100 or PT-1000
  6. Supports Python, C#, and LabVIEW

Pinout​

USB-DAQ-RD Pinout

RTD Sensor Wiring Instructions​

The following is the equivalent circuit diagram for the RTD inputs of the USB-DAQ-RD. The measurement principle involves using a precision citation current (Excitation Current) of approximately 1~4 mA, which is sent into the RTD sensor via the EX+ and EX- pins. As the current flows through the RTD sensor, a voltage drop occurs across it, which is then measured by an internal amplifier and ADC via the RTD+ and RTD- pins. Therefore, all four pins (EX+, EX-, RTD+, and RTD-) must be used when measuring temperature; none should be left as "No Connection" (Floating).

Wiring instructions for three common types of RTD sensors are as follows:

  • For short distances (within 3 meters), the measurement error between these three types of sensors is negligible.
  • If the sensor is more than 5 meters from the USB-DAQ-RD, a 4-wire RTD sensor is recommended.
  • For 4-wire sensors, refer directly to the 4-wire connection diagram below.
  • For 3-wire sensors, an external wire must be used to short RTD- and EX- on one side (or RTD+ and EX+ on the other side).
  • For 2-wire sensors, RTD+ must be shorted to EX+, and RTD- must be shorted to EX-.
RTD Wiring

4-Wire Connection​

RTD 4-Wire Connection