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What are the advantages and disadvantages of 3 wire and 2 wire outputs?

PNP or NPN, 3-wire vs AC/DC, 2-wire

PNP and NPN are the best technical options. Because of product availability, PNP is the best choice of the two.

AC/DC 2-wire interface issues can arise from the leakage current. Some loads (ones with small current demands) are not able to turn off due to this leakage current. 


PNP or NPN, 3-wire  

– Fewer interface problems

– Largest selection

– Lowest unit costs



AC/DC, 2-wire

– Many interface issues

– Smaller selection

– Susceptible to noise



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