Regarding the issue of thermal resistors
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How to use a multimeter to test the three terminals of a PLC thermistor module when their numbers are unknown? Should the ohm meter or voltage meter be used to determine which terminal is connected to one end of the thermistor, and which two terminals are connected to the shorted end of the thermistor?
I suggest that you remove it first and then conduct the test
The thermistor isn’t connected; it’s just about using a multimeter to determine which terminals of the temperature module are connected to a three-wire thermistor
First, remove the wires; then use a multimeter to measure the resistance of the thermal resistor. The pair of wires with very low resistance between them belong to the same terminal. Using a three-wire system in place of a two-wire system is not cost-effective, as the accuracy decreases as the cable length increases.
This hasn’t been tested; it was connected according to the wiring diagram, and if there’s a mistake, simply adjust the wires.
If that’s the case, you can determine it directly by checking the incoming line
There’s no need for a multimeter; a resistance box or a resistor of around 100 ohms will suffice.