Hall sensor connection

[rainman]

Hi all,

I have a question on hall sensor connection.

I have an electric actuator with the following connection




The hall sensor is supposed to connect to a PLC NPN input. The RED and BLACK goes to 24VDC and 0V DC respectively, YELLOW goes to my PLC input (which the PLC input common is pull high to 24VDC).

However, The PLC can't "read" the signal from YELLOW. Sadly I do not have an osciloscope.
While the actuator is moving, I measured across the YELLOW and BLACK and I get voltage like 12V, 17VDC....

Did I miss out anything?

Thanks all.

[Al_The_Man]

You have a source device so your PLC should be sink input.
Did you tie the GND to your PLC common?
with the load resistors in place, you should get a high to low reading on the sensors without any connection to the PLC.
Monitor with a voltmeter between common and Yellow, by turning the motor etc as slow as possible, before connecting to PLC.
If you turn slow enough you should be able to read a 24v to 0 transition, too fast and it will be anywhere in between.
Al.