Category Archives: Inductive

Wiring 3 Wire DC NPN and PNP Sensors




I recently received a question on PNP and NPN sensors. They wanted an explanation of what a sink is and how to wire one. Confusion over the Normally Open and Normally Closed function of the sensor is also a common question. Several diagrams will show a resistor attached to the blue wire and a load across the others, what does it all mean?

It is quite confusing sometimes the language we use for these devices. Sometimes it is the way we talk about the sensor and sometimes about the device we are connecting. (PLC)
We will break it down and go over the wiring to a PLC input. Let’s get started. Continue Reading!

Wiring an Inductive Proximity NPN PNP Sensor to the Click PLC

A proximity sensor (switch) is able to detect object presence without physical contact like a limit switch. No physical contact means that the switch has no parts that will wear out. The life span of the sensor is increased with less maintenance.
An inductive proximity sensor will detect ferrous metals. The sensor develops an electric field when metal (sensing object) is introduced usually killing the oscillation circuit of the sensor triggering the output.

We will be wiring an inductive proximity switch into the input of our Click PLC. The AM1-A0-4A is an extended range 12mm tubular sensor that can be wired into the PLC as a sink or source input. Let’s get started. Continue Reading!