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Proximity Sensor Overview
Every electronics engineer must be know about the Proximity Sensor so, we will discuss all related points to this.
This sensor sens only nearness object without any touch we called as Proximity sensor.
This is the sensor where we can see in Mobile phones device also.
In this sensor there are two primary component that is
- Proximity Switch
- Active Face
The sensor is targeting towards Motion Direction and detect the nearby objects.
This sensor is generate emitting electromagnetic field to detect and no object found then it will not detect anythings.
The best example is unlocking the mobile screen through face this this sensor detect your face and unlock the mobile lock.
The material is used as plastic or metallic.
Proximity Sensors there are four flavors such as Inductive, Capacitive, Magnetic, and Ultrasonic.
Types Of Sensors
If you are looking for sensor this sensor comes with the (IR) Proximity Sensor.
There are various and different types of sensors available in the market.
- Inductive Sensor
This sensor is design as per the application like square body, round body, metallic body, plastic body.
- Capacitive Sensor
Capacitive sensor also available in any forms. Such as cylindric, plastic and metallic body.
- Photo Electric Sensor
Mostly this sensors are available in rectangular shape or cylindric shape.
- Magnetic Sensor
Magnetic sensors come with actuate with magnet mostly used for door.
Design Structure And Working Principal
Ultrasonic sensors are used for object detection but they are also used for distance sensing, some proximity sensors do have analog outputs so they can do some distance sense.
Which is really helpful when setting up the system to make sure the sensors a good range to detect the object.
Note that the ones that operate over larger distances are going to be the larger units.
There are two different mounting barrel style sensors.
One is optimized for flush-mounted applications it is threaded all the way up to the face it's called a shielded sensor - and one sticks up like this it is called UN-shielded.
The reason starts the sensing region face towards the below that kind of like this.
It is possible to connect serial proximity sensors?
Sure! Why would you want to do that?
Suppose you have three sensors and you only want to know when all three sensors are active at the same time.
Run all these three into the PLC and further process will done through software.
If suppose sensors are placed a long distance then what will happens from the PLC and you don't want to spend the money running three sets of cables? Or running low maybe on your Inputs of PLC .
Well, then this is a neat trick to have in your toolbox.
Connect the first signal wire to the PLC wire of the next sensor. Same thing apply for third Sensor also.
Finally, connect the third sensor negative terminal to the negative supply.
How many sensors can you put in series?
That depends on the sensors.
That is the voltage drop across the sensor. We apply the as shown the above 2.5 volts.
So if I have 10 sensors in series, they would need 25 Volts but I only have a 24 V dc supply, so that is not going to work is it?
So the maximum number of sensors in the series depends on how much voltage you have available to drop across all of the sensors.
When placing sensors side by side, a good rule of thumb is to leave at least one sensor diameter of space between them so they do not interfere with each other.
Keep watch switching frequency between the sensor.
Looks like this one is 5000 Hz but you might see some that is 100 Hz.
So if you are trying to detect objects moving by faster than 100 Hz like gear teeth for example and you are using 100 Hz sensors, then you are going to miss some of the objects right?.
I like for my switching frequency to be at least twice the rate of the objects I am trying to detect.
Which type to use NPN or PNP?
That depends on what you are connecting the sensor to. The main thing to know is sinking and sourcing is always paired up.
PLC is sourcing positive supply, then the sensor must be sinking.
PLC is sourcing negative supply how do you remember which is which?
Well, if the sensor is sourcing current from the positive supply, then it is PNP think of P for positive.
So if you have an application where short downtime is critical then consider using quick-disconnect cables it'll save you money in the long run.
Proximity sensors have indicators to tell us when and which the sensor is active.
I love that, but it is not always easy to see when the sensor is mounted and I wish i tell that power was correctly connected.
Well, look at this. You can show the supply status and easy to get the cables with indicators to built in and the status of both outputs.
the neck of the sensor that are easier to see the indicator is on and now you can tell if the system is wired correctly at a glance.
The length of the various patch cables with the LED that indicators you can insert temporarily data to do diagnostics and tests.
Proximity sensor Can we use in a vibrating environment?
You can, but keep the vibrations below 55 Hz and a max amplitude of 1 mm for no longer than 30 minutes on any axis.
Can be a magnet trip of proximity sensor? It can.
If the answer is yes you have a capacitive sensor then they detect non-metal objects.
Inductive sensor does include metal magnet?
It is depends on how much metal is in the magnet.
Once we look at one is 30 milliseconds, so we will not get the stable results until the 30 milliseconds after the sensor is turned on.
The sensors which is small in a size that will the most accurate result.
It will only detect when the presence of an object, then range is betwwn small to large sensors are fine to detect.
Check all the sensor and pick which one is best uses is to look at the last character of the part number.
An H is a 12 mm 4-pin connector that all of Automation Directs M12 cables suffix is the 8 mm connector which maybe 3 or 4 pins.
Make sure you select the correct one the three-pin connectors are what Truck calls Pico fast.
Speaking of connectors, these multi port junction boxes are really handy for combining groups of 4, 6, or 8 sensors into a single cable.
Now that is resolve the cable management problem for a bunch of cable. We use sensors this is so much easier. And order the mounting brackets with sensors.
mounting brackets are very inexpensive and they can save you from the trouble of making it by your own. With all the different form factors that include such as cabling options, output types, etc.
The good news is the Automation Direct website has a fantastic parametric search that will help you find the sensor you need quickly.
If we use parametric for search that is a huge time saver for every one. That enough to you can easily start with proximity sensors.
Check out more video on start from how video. That show how you connect to a PLC and then the program of PLC to use them.
If you have any questions, please contact or comment down below free award-winning tech support during regular business hours.
We are happy to help you.
Also you can read this Ultrasonic sensor details information is covered.
Thanks for reading this article and hope you learn something new here this is the helpful information to electronics engineer.
Use this information to your project or keep memorize this for interview purpose.
I already write article regarding electronics engineering branch so you can check out here..