Hall effect sensor wiring question

1024alexjones · May 12, 2017

I am trying to use this (http://www.mouser.com/ds/2/833/Magnetic-Proximity-Sensor-MP1014-Datasheet-1075726.pdf) sensor to detect a weak magnet and to switch a relay (24vdc) so that I can switch a PNP input on a PLC input card. I have tried using the pull up resistor as the document suggests but I am getting nowhere and now im afraid that I have burned the sensor up somehow. How would you set this thing up?

Highland Controls · May 12, 2017

What relay are you using? 20mA isn't much and exceeds most relay coils.

tarik1978 · May 12, 2017

Which model do you have?
Operating Supply Voltage (MP101401) 4.5 to 18 VDC
Operating Supply Voltage (MP101402) 4.5 to 24 VDC
If it's the second one I would use a relay with a coil that has a resistance >1.2k (24v÷20mA).
Without a pull up resistor,the coil will be connected to Vcc and Out with flyback diode

1024alexjones · May 12, 2017

Highland Controls said:
What relay are you using? 20mA isn't much and exceeds most relay coils.

Something like an AB 700-HLT1U24

Highland Controls · May 12, 2017

Something like it, or it?

shooter · May 12, 2017

you will need a 3k resistor as recomended, so the current will be around 7 mA.
This is good enough for a PLC, however most PLC will work on 24 Volt and that is too high for the sensor, and a simple relais will also not work as the current is way higher as 10 mA.

LadderLogic · May 12, 2017

Unless I am missing something here, if you are using a pull-up resistor, you will be able to connect it directly to the PNP PLC input, only your logic will be opposite (input on when the sensor is off and vice versa).

The sensor output is an NPN transistor so this is a common method of a quick conversion.

Gomez_ · May 12, 2017

Have you tried measuring the output with just a meter and no relay hooked up?

How do you have your relay connected?

EDIT

+1 LadderLogic, I was also thinking about that.

Pete.S. · May 12, 2017

1024alexjones said:
I am trying to use this (http://www.mouser.com/ds/2/833/Magnetic-Proximity-Sensor-MP1014-Datasheet-1075726.pdf) sensor to detect a weak magnet and to switch a relay (24vdc) so that I can switch a PNP input on a PLC input card. I have tried using the pull up resistor as the document suggests but I am getting nowhere and now im afraid that I have burned the sensor up somehow. How would you set this thing up?

It's not that hard if you're familiar with electronics.

You connect the 24V relay between Vcc (24V) and output on the hall effect sensor. And that is it. No resistors.

Then you wire 24V to the relay contacts to feed the 24V input on the PLC when the coil is energized.

Relay coil has to be less than 20mA.

Pete.S. · May 12, 2017

Pete.S. said:
It's not that hard if you're familiar with electronics.

You connect the 24V relay between Vcc (24V) and output on the hall effect sensor. And that is it. No resistors.

Then you wire 24V to the relay contacts to feed the 24V input on the PLC when the coil is energized.

Relay coil has to be less than 20mA.

It's not the best way to solves this though.

Best way is to pick an industrial hall effect sensor, like http://www.baumer.com/de-en/products/presence-detection/magnetic-sensors/hall-sensors/

Second best way is to use a NPN to PNP converter instead of a relay. Like http://uk.rs-online.com/web/p/signal-conditioning/5329980/

A third option is to buy a NPN input module for the PLC.

It is possible to connect a NPN output to a PLC input designed for NPN outputs, but the resistor you need depends very much on exactly what design the PLC input is and how much impedance it has. It's the last resort option, not recommended.

Hall effect sensor wiring question

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