Looking for a sensor

geniusintraining

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geniusintraining
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I bought one from AD, Polarized Retroreflective and it works but its really hard to set and I think its for a different application type.

What I have is a cart that travels back and forth (about 80 inches total travel), I mounted a reflector on the cart and I need to know when that cart is less than 50 inches away from one end, looking at a digital signal.

This is the sensor I bought https://www.automationdirect.com/ad...flective_(ss_-z-_fa_-z-_fb_series)/farn-bp-0a

It has a pot and says that its adjustable but I dont think its for sensing distance, I think its for breaking the beam/reflector

I think I need a 'diffuse' type but the distance is only up to 300mm and I need approx 1250, this does not have to be precise, with in 1-2 inches is fine

Anyone know what I need and it can be IFM, Banner, whomever just nothing fancy (expensive)
 
Reading and searching a little more, I think I need a retro-reflective

Looks like IFM has a couple that may work O5D100, OID250

Now on to search for cheaper versions if anyone else makes them, not that IFM is bad only about 150 each, but cheaper would be nicer
 
I've used ultrasonic with teach points. Automation Direct has them for about $125.00 in that sensing range. You just teach 2 points and the output of the sensor switches between those points.
 
Thanks guys,

I guess I also forgot to mention the reason I used the reflector was I only want to pick up the cart, if someone or something is in the way I dont want to get a false signal that the cart is in position, I would use a prox but it can be parked anywhere in the 50 inches, so I need to read 0-50 inches
 
Had a similar issue with an AGV at the straight end of its travel. If your cart is moving in a single direction back and forth use a downward looking polarized retroreflective photoelectric sensor mounted on the cart and attach reflectors to the floor at the distance you want to sense position. I used AD sensor and reflectors. Worked like a charm.


https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/photoelectric_sensors/photoelectric_accessories/reflectors/rl106

https://www.automationdirect.com/ad...l/polarized_retroreflective_(axial)/dmp-0p-1h
 
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If you use retro-reflective, you want polarized so it only senses the polarized reflector. If your sensor is pointed straight at (in line with) the travel path of the target, but you only want it to switch at a certain distance, then I think any type of retro-reflective sensor will be problematic. So that makes me think that a laser or ultrasonic with teach points will be better, but then how do you filter out false triggers from the wrong object?

Could it work better if you used a polarized retro-reflective sensor from a position where it would only hit the target at the correct distance by moving the senor out of line with the target, so that when the target is in position, the alignment with the beam occurs?

I may have read into this an incorrect assumption that the sensor beam will be always pointed directly at the target...ignore all this if my assumption is incorrect.
 
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I had to invent a way to detect a transfer car being within 3' of the end of travel during an install many years ago. I solved it much the same way OKiePC is suggesting.
I used a Photoswitch 42RL1 photocell (most of you will be too young to remember them) and some reflector tape that I found at a local truck stop. The photocell was mounted at an angle to the travel and adjusted so that the reflector tape came into view during the last 3' of travel. That setup was still working about 10 years later.
 
mendonsy said:
... and some reflector tape that I found at a local truck stop. ...
Click to expand...


OT: my brother told me he had spurious signals for a photo-sensor aimed across a conveyor line, then he noticed it happened when plant personnel, wearing photo-reflective vests, walked by, or even someone with a white hard hat. I suspect he was not the first.


The piece of cardboard he tried first was too bright, until covered using a black sharpie. So it seems Staples is in the automation industry now, along with truck stops.
 
drbitboy said:
OT: my brother told me he had spurious signals for a photo-sensor aimed across a conveyor line, then he noticed it happened when plant personnel, wearing photo-reflective vests, walked by, or even someone with a white hard hat. I suspect he was not the first.


The piece of cardboard he tried first was too bright, until covered using a black sharpie. So it seems Staples is in the automation industry now, along with truck stops.
Click to expand...

When I worked in the food industry, I found out that cardboard is highly reflective. I used to have a table listing generic materials and the relative reflectivity. Black rubber materials also can be problematic. Polarized reflectors with polarized sensors almost always takes care of the false triggers you can get from standard non-polarized optical sensors.
 
drbitboy said:
OT: my brother told me he had spurious signals for a photo-sensor aimed across a conveyor line, then he noticed it happened when plant personnel, wearing photo-reflective vests, walked by, or even someone with a white hard hat. I suspect he was not the first.


The piece of cardboard he tried first was too bright, until covered using a black sharpie. So it seems Staples is in the automation industry now, along with truck stops.
Click to expand...

For years we’ve never had issues with our photocells, until recently some high end fancy designer luggage started coming out. There is luggage that is so highly reflective that the light reflects right back and never picks it up or causes it to bounce so fast the signal is no good. Adjusting the margin can help some.
 
I have a used Banner Q4XTKLAF600-Q8 you can have for free. It’s max range is 600 mm, so that won’t meet your requirements but could be used for testing.
 
Thanks guys!

I have a couple IFM's on the way, I will let you know.

I appreciate the offer Caveman!! 🍺
 
I went to a conveyor unit that had run fine for years, but suddenly stopped running and was constantly trying to move non-existent parts.

Turns out they replaced all the mercury vapor high-bay lights with LED fixtures and there was one directly over a diffuse photoeye that was looking up through the conveyor. The LED spectrum of the new light turned the photoeye on, and kept it on.

The quick and easy solution for the customer was to put one mercury vapor light back in that spot.

Not as good as the workers wearing construction vests though.
 

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