How To Calibrate A Rosemount 644 Temperature Transmitter?

Equipment required for calibrating a PT100 temperature transmitter (with HART protocol)

• Standard resistance box (or signal generator)
• 644 temperature transmitter
• HART handheld communicator
• High-precision digital multimeter (or calibrator)
• Several wires
• Resistor
• DC 24V power supply

1. Connect the resistance box to the temperature transmitter input, ensuring the use of three-wire/four-wire connection method.

2. Connect the power supply, temperature transmitter, 250-ohm resistor, ZYS digital multimeter in series to form a closed loop circuit, paying attention to polarity.

3. Connect the HART 475 handheld communicator across the resistor terminals. Wiring is complete.

1. Determine the transmitter's range and select at least 5 points as measurement points.

2. Power on and set the input resistance to the lower limit of the range. Check if the displayed data on the transmitter and the digital multimeter match. If not, adjust the lower limit value in the HART 388 communicator to match the corresponding data.

3. Adjust the upper limit value as in step 2.

4.Repeat the above steps for all test points.