Three-wire and four-wire thermistor configurations
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Three-wire thermal resistors A1, B1, and C1 are used on-site, while the program is configured for a four-wire system with A, B, C, and D. Now, if AC is shorted together and A1 is connected to B1 and D is connected to C1, is there any problem with this connection? Currently, the resistance measured at the site is around 120 ohms at approximately 50 degrees, but the program shows only 1 degree
Perhaps A is short-circuited to A1, then B1 is connected to C, and C1 is connected to D; you need to check the manual of the RTD module for this!
Look at the four wires ABCD; those two form a pair, for example AB or AC. Then, A1B1C1 also forms a pair (they are short-circuited, with a resistance of almost 0). Identify which wire is alone, and then connect that single wire to one of the wires in the pair – this way the number of wires becomes 4. After that, just connect them according to the short-circuiting pattern of ABCD. Generally, the temperature difference will be around 1-4 degrees.