2 wire NPN sensor wiring, sinking sourcing?

Hi there,

I have a 2 wire npn sensor. For example in this diagram:


I'm guessing i should connect it to a PLC dc sourcing input as such? Would i need a resistor between the PLC #1 DI to the sensor Collector ?
https://snag.gy/TEpJXM.jpg

ow can i just have the brown wire of the sensor goes to input 1, and black wire goes to common (0 Vdc)? Assuming the PLC sourcing digital input internally already has a resistor?

I always used a 3 wire npn sensor, and wiring is done as such:

Your PLC will act as your load. Depending on what your common point (+ or OVDC) is on your PLC, will determine which wire is connected.

Two wire sensors are known for leakage. Please check the specifications on the sensor to determine the leakage current. Calculate the amount based on the input impedance of the PLC to determine if it will falsely trigger the input.
If it will then you may need resistor.

http://www.plctalk.net/qanda/showthread.php?t=72951
The above thread is similar.

Hope this helps you out.
Regards,

Thanks for the reply garry,
the leakage of the sensor i have is approximately 0.7 ma.

And if the plc input i were to use is a sourcing type, such as this: http://sie.ag/2v2jkSc

Based of the spec, the typ input current is at 7ma. Guess it wont work then? but on the other than, it also support 2-wire BERO

The specs for the card indicate a value of 7ma to have the card indicate an ON or 1 condition.This means that 10 of these 2 wire sensors. (Leakage 0.7ma) can be used per card common before you will get false signals.

Regards,

If you really want to use that sensor, connect it to a small SPDT relay and use the relay contact as your PLC input. That will eliminate the leakage problem for about $10.

a simple resistor on the input to gnd is fine. (make it 10kilo and 1 watt.