To clarify the situation:
As Tonyr1084 stated; this is a standard proximity sensor which I expected to output a signal when a ferrous material is close to the end of the sensor (closed state) and output no signal when the ferrous material is removed (open state)
What I am seeing with the sensor is:
VS = input voltage
VO = output voltage
When the sensor is in the Closed State VO= VS.
When the sensor is in the Open State VO= VS-2. I was expecting this to be VO=0

Those measurements indicate the sensor is damaged...

With PNP =on, output should =VS if open collector and no load.
With PNP = off, output should = ~mv, if open collector and no load.

 

With PNP = off, output should = ~mv, if open collector and no load.

Leakage of the PNP into high resistance meter?

 

Leakage of the PNP into high resistance meter?

Yes sir. The collector is floating but the meter presents a tiny load

 

This should work.
When metal is detected (within 8mm), output should be approx +12v
When no metal is detected, output should be ~mV.

 

This should work.

Pin 3 is the negative lead on the sensor.

 

Pin 3 is the negative lead on the sensor.

Fixed...thank you..

 

Sounds to me like the TS has been measuring the leakage current AlbertHall mentioned.

 

This should work.
When metal is detected (within 8mm), output should be approx +12v
When no metal is detected, output should be ~mV.

View attachment 223974

Got it to work.
The signal Conditioner (for which there is no datasheet) that it connects into was pulling the Pin 4 Voltage up.
I ended up with a 330 Ohm resistor in the RL position which dropped Pin 4 to 0.3V when the sensor is OPEN and ~12V when CLOSED

Thanks for all the Help.

 

To clarify the situation:
As Tonyr1084 stated; this is a standard proximity sensor which I expected to output a signal when a ferrous material is close to the end of the sensor (closed state) and output no signal when the ferrous material is removed (open state)
What I am seeing with the sensor is:
VS = input voltage
VO = output voltage
When the sensor is in the Closed State VO= VS.
When the sensor is in the Open State VO= VS-2. I was expecting this to be VO=0

SORRY, but that is NOT a STANDARD proximity switch, unless you are using it incorrectly with no load current drawn. And based on the final results this was a correct evaluation. Open collector devices must ALWAYS have a proper load connected in order to function correctly.