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Sensor issues

Sensor issues

Sensor issues

hello I am new here and I hope I can have some help with my new project!

Chlorine tablets are being counted on a conveyor by a sensor and when count reaches 100 a gate is open(air piston driven) so they can fall inside a bucket. This go on and on for 8 hours.

Hardware use:
- click PLC
- ac solenoid valve
- air piston
- sensor

The issue is with the sensor, I already used Two different types but problem doesn't seem to go away.
The sensor start counting and everything seems good for like one hour but after this it stops counting. The environment is really dirty because chorine raw material is really dusty so I tried cleaning the glass of the sensors and having some ventilation but nothing works. So every time the sensors stop sending signals when tablets are passing by I have to stop everything and realign the sensor again(every time I clean the sensor glass I have to realign so it can detect the chlorine parts again ).
-sensors I already tried were the Omron E3Z-ll81 and an infrared proximity switch. Is there a sensor for this type of environment or what it seems I have been doing wrong here ?
I have some experience with PLC’s but I consider myself still a beginner although I have done already lot of projects in the past but this is the first time I am trying to work with sensors!

Thank you much !

RE: Sensor issues

Got a picture of the sensor tablet scene? That would help a lot.

What does the tablet even look like?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Sensor issues

Have a look at some ultrasound sensor that might solv it.
Exempel IFM UGT528 UGB00300GOKG (stainless steel)

Depens on size of tablets and where you ca put the sensor.

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

RE: Sensor issues

Maybe its not really the sensor. Maybe you're overrunning your counter and when you power-down to clean the sensor it resets the counter. Have you tried just re-booting when you have the problem without touching the sensor? Otherwise it sounds like a problem with the mounting bracketry if you have to realign it each time.

RE: Sensor issues

As I remembered how this laser photocells are constructed at least in the past, if you have one that is both sender and receiver is that when you adjust the distans window you actually mechanically adjust the angle of the sender and receiver inside the photosensor, making the angel where the beam hits the object and sending it back smaller or larger and moving the sensing window closer or further away.
The sensing window isn't very large making them very sensitiv.

Meaning if the beam does not hit the target and can be reflected back in the right angle the signal goes zero.
And with a laser beam sensor you have a very narrow beam, witch of course is good if you want to detect small objects with good precision.
But if you have it in a dusty environment and especially if there is crystals that can break of the light the senders light will be optically refracted and spreading out when going through the dusty "glas" and the same when it comes back to the receiver.
Most laser and photosensors does not except all wave length and a too week a signal back to produce a high signal.
This would cause a lot of problems if it would except all kinds of light to set it high.

Since we do not know exactly how large this tabletts are and how fixed in position they are coming out on this conveyor or where the dust comes from it's hard to give advice on a solution.
Can the sensor be put above detecting from above I am guessing it is horisontal now, is there equally as much dust there?

I do not think it's the plc.
But I am a programmer so of course that would be the first thing I would have checked. winky smile

Best Regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

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