Proximity sensor wiring to PLC/DCS


Thread Starter

VK Aggarwal

Can someone let me know how to wire Namur, 2 wire and three wire pnp/npn proximity sensors to DCS/PLC assuming the field to be safe area.I would like to wire these sensors to conventional digital input cards of PLC/DCS.


VK Aggarwal
What kind of digital input card are you using? Is the power for 2-wire coming out of the PLC or is it external?

In general, for a 2-wire switch, the power goes to the positive terminal of the switch and the negative goes back to the PLC. Ensure the same reference is used on both PLC/DCS and the switch. For a 3-wire, the power and common goes to the switch and the signal back to the PLC/DCS. Even in this case its very important to maintain the reference voltage.

Hope this answers your question.