Alejandroesteban83

Sensor issues

6 posts in this topic

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

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 !

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sensor is sensing and not counting... counting is done in the PLC logic.

for dusty environment i would prefer to not use optical sensor...capacitive or ultrasound or something else would be better... and if for some reason it had to be an optical sensor, i would definitely not go for a diffuse sensor, specially not one that responds to amount of reflected light and does not even have a background suppression. bean-through or polarized-reflective would perform better in such environment. also why not automate sensor cleaning? different options come to mind, perhaps simply occasionally blowing some air at it. 

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11 hours ago, Alejandroesteban83 said:

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

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 !

hi thank you for your answer, the counting stops because the sensor can’t detect the object anymore after about one hour of working fine. It doesn’t have to be an optical sensor so I will try the capacitive one then, through beam is not posible because tablets are aligned all together so the beam will always be break, thank you for your recommendation I will try it right away !

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tablets are aligned all together 

what is the shape and size of the tablets? what is the exact stack order in which they are "aligned all together"?

if they are cylindrical, there is a big difference between grouping on same axis (one axis aligned with cylinder axis) and grouping side to side (cylinder axis are parallel but not the same axis). later one allows sensor to be moved off enter and look at the perimeter.

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Tablets are 3” wide and 1.5” height, they are all going in the conveyor together next to each other, I’ll send a video tomorrow so you will see it more clearly, thank you for your response 😊

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that will show the rate too...

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