Proximity Sensor Wiring Issue? Help needed.

[john-100]

Hi Ronald

use the 24V supply as the G540's 48V supply is more than the sensors 6 - 36V supply range

as the sensor has a N/C NPN output you can only connect one sensor directly to each G540 input


the G540 input circuit consists of the LED within an opto isolator that is connected in series with a 2200 ohm resistor powered from a +12V supply

when an input is grounded approximately 4.5 mA will flow from the G540 input to ground
you can measure this with a multimeter connected between the input and G540 ground
(the current is limited by the 2200 ohm resistor inside of the G540)


John

[ronald44181000]

So basically I had it hooked up correctly the first time I tried but instead of a 24V Wall Wart I had used a 9V Wall Wart. When I did that though the Probe would light up until I turned the Controller on and then Shut Off and not detect anything. I'll give it a go with the 24V Wall Wart.

[john-100]

provided the sensor has an NPN open collector output so there is no components connecting the + supply to the output

you can check this by powering the sensor and measuring the voltage between the blue ground wire and black "output" wire

an output near 0V will indicate an open collector output

this is what you have when a sensor with a NPN open collector output is connected to the G540 input 1




if the voltage between the sensor black output and blue ground/ 0V is more than 12V and possibly
a voltage near to 24V will indicate an internal pullup resistor connecting the +24V supply to the output

in this case you will need to use a diode to connect the sensor to the G540 input

the diodes anode goes to the G540 input and anode to the sensor NPN output

this will block any current flowing out of the sensor and back through the LED in the G540s opto-isolator (LEDs are not very good rectifiers the reverse breakdown voltage is only a few volts )





John

[ronald44181000]

I checked my circuit with a 24VDC power supply and by measuring the Voltage between the Blue and Brown wires I have a voltage of 27VDC. I realize that I need to run a Diode between the Black Sensor Wires and the G540. What I can't figure out is what Size of Diode should I use?

Any help would be Greatly Appreciated.

[john-100]

Hi Ronald

any silicon small signal diode like the 1N4148 would do

a 1A rectifier diode like the 1N4001 to 1N4007 will be mechanically more robust


John


PS


the 1N4148 has a glass encapsulation and thin wire connections

https://www.vishay.com/docs/81857/1n4148.pdf



the 1N4000 series has a larger epoxy encapsulation and thicker wire to carry a 1A current

https://www.digikey.com/en/datasheet...ivision-1n4001

[ronald44181000]

Hi Ronald

any silicon small signal diode like the 1N4148 would do

a 1A rectifier diode like the 1N4001 to 1N4007 will be mechanically more robust


John


PS


the 1N4148 has a glass encapsulation and thin wire connections

https://www.vishay.com/docs/81857/1n4148.pdf



the 1N4000 series has a larger epoxy encapsulation and thicker wire to carry a 1A current

https://www.digikey.com/en/datasheet...ivision-1n4001

Thanks for the quick response, I had gone out and bought a package of Transistors and Diodes to make sure I had at least a set of each. Ans though there was a reference for the Transistors there wasn't one for the Diodes that you listed in your Diagram. I hope this fixes this issue once and for all as you're the only assistance that I could find on this subject other than generalizations from my usual suppliers including Gecko Drives.

[john-100]

Hi Ronald

whats the part number of the diode you have ?

John

[ronald44181000]

Hi Ronald

whats the part number of the diode you have ?

John

IN4001 is the one I am going to use.

[pip9ball]

Hi John -

Hoping you can help me out.

I'm using a Gecko G540 board which is powered by a 36-48Vdc power supply.

The proximity sensors I have are: http://www.fctaiwan.com/en/Productde...&ProductId=124 (F3N-18TN05-N)

According to the wiring diagram, the input voltage should be between 12-24VDC.

Currently in mach3, when I move the sensor close to metal the LED on the sensor lights up, however the signal in mach3 doesn't trigger. Do you think it's possible to use a pull up resistor between the brown/black wires? If so, what size do you recommend?

Or, is it better to purchase a separate 24Vdc wall wart to power the sensors?

Thanks,

Phil