Rosemount 644 wiring diagram

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The Rosemount 644 temperature transmitter is available in two versions: the single-input 644H and the dual-input 644S. Engineer Yang from Xi’an Jingmin Electromechanical explains in this article how to wire the 644 temperature transmitter; everyone is welcome to learn about the precautions related to wiring the Rosemount 644 temperature transmitter together. Question 1: What are the functions of these four terminals at position ① in the diagram below? Question 2: What are the functions of these three terminals at position ② in the diagram below? Question 3: What are the functions of these three terminals at position ③ in the diagram below? Question 4: What is the purpose of this pin at position ④ in the diagram below? Question 5: What do the L and H positions of the dial at location ⑤ in the figure below represent? Question 6: What are the functions of these two terminals at position ⑥ in the above diagram? With reference to the diagram above, it is easy to understand the function of each position in the 644 unit: Answer to Question 1: The four terminals at position ① in the diagram are the input signal terminals of the single-input 644H temperature transmitter ； Answers to Questions 2 and 3: The terminals at positions ② and ③ in the diagram are the two input signal terminals of the dual-input 644S temperature transmitter ； Answer to Question 4: The pin at position ④ in the diagram is used to connect the display screen. In practice, some measurement points are equipped with display screens while others do not; one can open the instrument cover on site to check this. Answer to Question 5: In the diagram, positions H and L at ⑤ indicate the locations of the fault modes, that is, where the physical hardware alarm switches need to be set. H stands for high, L stands for low. Answer to Question 6: 644. The power terminals of the temperature transmitter. Remember this wiring diagram for the 644 temperature transmitter; there’s no need to worry about wiring it. Points to note when wiring the 644 temperature transmitter: 1. When connecting the thermal resistor input: The temperature transmitter can accept various thermal resistor configurations, including 2-wire, 3-wire, or 4-wire configurations. If the transmitter is installed at a location far from the 3-wire or 4-wire thermoresistors, and the resistance of each lead is at most 60 ohms, then the transmitter can operate as specified without the need for re-calibration. In this case, the wiring between the thermoresistor and the transmitter should have a shielding layer. If only two leads are used, and the two thermistor leads are connected in series with the sensor element, significant errors can occur when the length of the leads exceeds three feet. For 2-wire and 3-wire thermistors, additional lead resistance errors occur when the ambient temperature changes.