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3-wire RTD connection
In a 3-wire RTD configuration, AI+ terminal will output a precision current
excitation, 500 µA to RTD sensor and flow back through the Ex- terminal
and AI- terminal as shown in Figure 3 . Since the voltage generated by
the RTD connecting the AI+ terminal and the voltage connected to the AI-
terminal will cancel each other, this connection can effectively eliminate
the influence of the lead wire resistance, but in practical applications, the
resistance of the two lead wires is difficult to match completely, so there
will still be a certain degree of mismatch error.
Figure 3 3-wire RTD connection
