Inductive Sensors - PNP vs NPN - N.O. vs N.C. - Datalogic
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- čas přidán 1. 04. 2018
- In this video we go over the basics of what an inductive sensor is and how they work. We also define the difference between momentary and maintained switches, NPN and PNP transistors, and normally open verses normally closed switches.
If you are interested in buying some Datalogic inductive sensors as used in the video please visit the following link: www.flexibleassembly.com/auto... - Věda a technologie
I needed to know this, and watched a couple of videos.
This is the best explanation in the shortest amount of time without skimping on important details that were crucial for me to really get it, kudos!
I need to watch this video again loads of information! Thank you for the video.
@komigennufan Thank you for your feedback. I will take this into consideration in future videos! Also, all our videos have full closed captions if that makes it easier to understand me.
Thank u for great explanation
excellent video..well done
thank you #########very nice explanation ## thanks again
Nice video thank you!
Thumbs up for that awesome Toyota MR2 turbo at the stop light!
Too many thanks, you're help me to understand
Glad to hear that!
To better understand it, in NPN sensor drawing (4:16), top part is actually PLC input (could be relay or something else). There is permanent 24VDC on PLC input and wire going from PLC input to sensor is going to the collector of transistor which is switching negative (N pn - switching negative).
If you take DC voltage multi-meter and connect black probe to 0VDC and red probe to PLC input and there is 24VDC, that's mean you have to use NPN sensor. On other side, if you want to test the sensor, connect red probe to 24VDC and black probe to sensor output, if multi-meter display 24V, then it's NPN sensor. Sensor have to be in ON state of course.
IN PNP sensor drawing (4:16), bottom part is actually PLC input (could be relay or something else). There is permanent 0VDC on PLC input and wire going from PLC input to sensor is going to the collector of transistor which is switching positive (P np - switching positive).
If you take DC voltage multi-meter and connect red probe to 24VDC and black probe to PLC input and there is 24VDC, that's mean you have to use PNP sensor. On other side, if you want to test the sensor, connect black probe to 0VDC and red probe to sensor output, if multi-meter display 24V, then it's PNP sensor. Sensor have to be in ON state of course.
Thank you for the information!
Nice video clip, keep it up, thank you for sharing it :)
Nice
How about 110/230V AC sensors? Are they PNP and NPN too? And does it matter if they are connected to L or N?
Thanks, the video was good. I have two questions:
1. Why do I need an oscillator to generate magnetic field? I think current through a coil is enough
2. Why the amplitude of is oscillation gets dampened when metal comes in contact with the magnetic field?
The oscillator is used to drive the coil and detect changes to the magnetic field as metallic objects enter into the field and disturb it. To answer your second question here is an excerpt from a well written wikipedia article - "When power is applied, the resulting oscillation is a high frequency alternating electric current in the coil that has a constantly changing magnetic field able to induces eddy currents in proximal (target) conductors. The closer the target is and the greater its conductivity (metals are good conductors, for example), the greater the induced eddy currents are and the more effect their resulting opposing magnetic fields have on the magnitude and frequency of the oscillation. Its magnitude is reduced as the load is increased in a non-magnetic conductor like aluminum because the induced field in the target opposes the source induction field, lowering net inductive impedance and therefore simultaneously tuning the oscillation frequency higher. But that magnitude is less affected if the target is a highly magnetically permeable material, like iron, as that high permeability increases the coil inductance, lowering the frequency of oscillation." Source: en.wikipedia.org/wiki/Inductive_sensor
Can you adjust the distance sensing of the inductive sensor? Say for example, 1 inch away from the sensor, would it be able to detect the object? Thank you in advanced for the answer.
For the Datalogic inductive sensors there is no way to tune the distance they sense (like you would focus a camera). The operating distance (range) of Datalogic inductive sensors is determined by the diameter of the sensor and the shielding type. The magnetic field they produce that detects metals is proportional to the diameter. For example an unshielded sensor with an 8 mm diameter can detect as far as 1.5-3 mm while a 30 mm sensor can detect 10-20 mm. The variance in those ranges is dependent on the type of material being detected (ferrous metals have increased range). I'd recommend using a sensor with a longer range than needed, then recessing the sensor farther away from the part being detected to reach the desired distance.
can you show the internal components of the proximity switch and how its working in detail. Does all the proximity sensor will have switch itself or externally need to connect
The inner workings of these digital Datalogic inductive sensors (proximity) are a series of elements designed to read changes in oscillating magnetic fields. They include the following circuits:
1. Field sensor
2. Oscillator
3. Demodulator
4. Flip-flop
5. Output
These specific sensors have a few wires coming out of them. 2 for power and one for the output. The output can be connected to whatever PLC or circuit you design for your purposes.
For more general information proximity sensors and how they work check out this article:
en.wikipedia.org/wiki/Inductive_sensor
I have just one question: Where can i get this keyboard with cruise ctrl??
LOL! Good eye! Those are custom keycaps that I made for a keyboard I designed on WASDkeyboards.com
how NPN and PNP relates with concept of sinking and sourcing?
It looks like these sensors have a low sensitivity. The sensing distance is 5 mm or even less. Is there some way to have a 25 or 30 mm distance for sensing very small metallic objects like 1-2 mm dia screws/nails ?
These particular sensors are very small, which directly relates to their sensing distance. For inductive sensors the larger the sensing surface, the larger the sensing range. For examples the induction sensors used in roads for monitoring traffic have a diameter of over 3 feet and can sense the present a vehicle sitting well above 10 inches from their surface. The size of the magnetic field generated by the inductive sensor is generally directly related to the size of the sensor itself.
If you had a much larger inductive sensor you could easily detect a metallic object 25-30mm away, however the size and material properties of that object will dictate how "sensitive" the sensor would have to be. Also remember that ANY other metallic objects within that larger sensor range would also trip the sensor. Your fixtures would have to be made of another material.
In short, an inductive sensor can "see" metal when it interferes with the magnetic field it produces. If the object isn't ferrous or too small to create enough interference you would most likely be better off with a photoelectric sensor.
The small range on these sensors help them eliminate any false positives. For automation purposes where a metal surface will pass directly over the sensor these are perfect. For longer range sensing of objects usually photo electric sensors provide better results.
Is this Conventional Flow Theory?
Is there a clear advantage of NPN over PNP? Or they are suitable for different purposes? Can U give some examples?
NPN transistors are theoretically more efficient than PNP transistors due to electron theory versus hole theory.
crown cork is stainless steel type of material then how it isattracted by inductive proximity and refro reflective photo sensor?
Inductive sensors can detect the presence of stainless steel, but it will have a reduced sensing range due to the reduction factor of SS. Materials are not "attracted" to the sensor, they are just detected by the change in the electromagnetic field. There are special non-ferrous metal inductive sensors that can more easily detect SS.
A retro-reflective photo sensor is entirely different technology. It relies on the reflective properties of the target and requires line of sight. You do not need to see the metal you are detecting with an inductive sensor.
Photoelectric sensors and inductive sensors operate very differently.
Kindly tell me difference between sourcing and sinking with practical purposes
Sinking and Sourcing are terms used to define the control of direct current flow in a load. A sinking digital I/O (input/output) provides a grounded connection to the load, whereas a sourcing digital I/O provides a voltage source to the load. A sourcing input will always provide power to a sinking output. Whereas a sinking input will provide resistance for the sourcing output which provides power for the circuit. More explanations are found in this article: instrumentationtools.com/difference-between-the-sinking-and-sourcing/
i want to know how much voltage for a ECU in a automotive vehicle is required to turn on the base, i heard 5v is short to ground or something..?
Considering most car batteries are 12V I would guess the ECU would need somewhere between 9-14V to operate properly. That is just a guess. There will be a min/max for the specific model ECU, that information you would need to get from the manufacturer to ensure you are providing ample power without damaging the unit.
They don't provide enough info on how the ecus work totally other than the basic technician level.
I'm sorry I can't provide more information to help you on the matter, someone who's expertise is in automotive electrical engineering could provide you with much better information. Good luck!
What about PNP/NPN 3 wire sensors? Efector offers a lot of sensors that say PNP/NPN but the wiring isn't a plug n play the way you would think.
A 3 wire sensor would have 1 for power, 1 for ground and 1 for the signal to be sent to a PLC.
@@FlexibleAssembly With my experience if a system that uses an NPN sensor to trigger something (for example) a universal PNP/NPN will not work with factory wiring of the machine.
I'm not sure what type of machine you are referring to. Typically any NPN or PNP sensors would be plugged into a programmable logic controller (PLC) which would handle the signal and logic that it drives. If a machine requires a sensor to be plugged into it directly that you would have to use the specific sensor listed in their specifications.
Datalogic doesn't sell any inductive sensors which are 'universal PNP/NPN'. They have one type of circuit or the other. It would be the PLC that could be universal to handle either type of sensor.
Hi what is the name they tool you use to turn on the sensors?
It is an Inductive Sensor Tester from Datalogic. Basically a circuit which connects a battery and LED to the sensors so can you wire them up and test their function before installing.
Can we adjust the sensing distance?
The sensing distance cannot be adjusted for these inductive sensors. Each sensor (depending on size, shielding, and type) has a fixed distance that it can sense. This range changes based on the type of metal being sensed. Ferrous metals will detect farther away than non-ferrous metals. Data sheets are available for each sensor which provide a sensing range diagram based on different metals.
Do you sell that Datalogic test device?
We do sell the Datalogic Sensor Tester / Power Supply. Please email info@flexibleassembly.com and use the part number 95ACC2850. It is a special order part, we don't have a product page for it (yet).
Why my npn inductive sensor can detect all kinds of materials like plastics?
This video is specifically talking about inductive sensors, which can only detect metal. You may have a photo sensor or a different proximity sensor. Plastic can't interfere with the electromagnetic field generated by an inductive sensor so it's impossible to detect the presence of plastic alone. Perhaps the plastic you are using has metal parts within it, or the sensor is mislabeled. NPN or PNP makes no difference when it comes to detection of an object, it's just the way the circuit is configured.
Thank you for the information. I have anothet question. Is it possible for the inductive sensor to read as metal if i put non metal material that has a liquid in it
You're welcome! An inductive sensor would not be able to 'see' a non metal material with or without liquid in it. Only metal would disrupt the electromagnetic field enough to trigger the sensor. Metal suspended within a fluid could set it off however.
When a Proxy sensor become less responsive due to extremely low temperatures (-30c) will increasing voltage help ? for example going from 6 volts to 9 volts.
These specific inductive sensors have a recommended operating range of (-25 ... +70 °C). At temps below -30C I'd assume the resistance to shock impacts would drastically drop in these models. Special inductive prox sensors for industrial freezers rated to -100C seem to have better shielding to reduce these issues. I'm unsure if increasing voltage would help with lower temps.
So NC PNP and NO NPN must be the same
Almost, but not quite. One will provide a grounded connection to the load, whereas the other provides a voltage source to the load.
For some reason this video stays on black screen for me while all others don't... Great :(
Strange! Perhaps trying a different browser will help. We don't run ads on our videos so I don't think it would be a conflict with any ad blockers you may be running.
Nice video thank you!