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Old September 21st, 2022, 11:59 AM   #1
BradleyAllen1
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Looking for suitable Photoeye replacement

Im looking to replace a retroreflective Photoeye with a throughbeam or light curtain. The retroreflective eye is causing some issues with reflective tape on boxes so i want to eliminate this problem. 42EF-P2MPB-F4 is the part number for my photoeye. Standard M12 connection running to an allen bradley SIO module, 24vdc PNP sensor. Im just not sure which specs are important when finding a replacement. And if my replacement is a throughbeam sensor, i have questions as to what additional changes would be required. I would then need an additional M12 cable for the extra powered device. And just not sure what that looks like in the logic. If studio would require any changes due to the extra cable, or how would i provide power to that additional device (transmitter/receiver)--- Any info would be greatly appreciated. I am a controls technician but still a little green in my second year.
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Old September 21st, 2022, 12:06 PM   #2
alan_505
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Unless the item is part of the IO tree then the PLC does not care what is connected to a digital Input.
As for wiring the transmitter of a through beam unit will only need power so again the PLC does not know about that.
Just get a supply from where the current Photoeye gets its power from and run it to the transmitter, and run the receiver signal back to the PLC using the existing wires.
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Old September 21st, 2022, 01:36 PM   #3
TWS
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We use these: https://www.keyence.com/products/sensor/laser/lr-t/.
Very precise sensing up to 5 meters. NPN, PNP or analog output.
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Old September 22nd, 2022, 04:43 AM   #4
Puddle
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Quote:
Originally Posted by BradleyAllen1 View Post
Im just not sure which specs are important when finding a replacement. And if my replacement is a throughbeam sensor, i have questions as to what additional changes would be required. I would then need an additional M12 cable for the extra powered device. And just not sure what that looks like in the logic. If studio would require any changes due to the extra cable, or how would i provide power to that additional device (transmitter/receiver)
For PNP you should have three connections: power, common and switched output. If it's both NPN and PNP you may have a fourth connection for the NPN output too.
For a throughbeam you would need power to the emitter, but you can just pick this up from the power and common terminals of your receiver.
As Alan said, all the PLC is looking for is 24v coming back to the input card.

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Originally Posted by TWS View Post
We use these: https://www.keyence.com/products/sensor/laser/lr-t/.
Very precise sensing up to 5 meters. NPN, PNP or analog output.
These are good and very robust, but Keyence stuff can be quite expensive. If the analog is needed, it's only available on the 5m model and not the 2m.
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Old September 22nd, 2022, 08:13 AM   #5
Keystone
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Banner has some polarized sensors that only work with retroreflectors. Designed to work with "shiny" objects. This way you do not need to power an emitter for the collector (input). Call Banner Eng. they were always helpful for me.
Item: https://www.bannerengineering.com/za...detection.html

No - I do not work for banner we have a lot in our plant.
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Old September 22nd, 2022, 10:03 AM   #6
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If you are going with the through-beam have a look below

https://www.automationdirect.com/adc...%20Receiver%22)


This would be a good set, if you look at the bottom you will find the wires and mounts on the bottom

https://www.automationdirect.com/adc...sors/fbr-lp-0e

https://www.automationdirect.com/adc...sors/fbe-00-0e
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Old September 22nd, 2022, 10:22 AM   #7
IanM8040
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sometimes you don't need a different sensor, you just need to mount them differently.

for instance, if you are reading reflective tape as part of the retroreflective sensor and it's triggering more than you need to. then consider that you should try to put your current sensor and reflector at an angle to the parts coming by, reflectors for these sensor are built to reflect back anything at the angle it came in at. tape on a box is not, so while you can get a reflection off tape while point at it from a perpendicular angle, you won't get that is most cases when you shoot off to the side.

If you can't just move the sensor and reflector at an angle, then possibly change the height they sit at to avoid the tape as much as possible.

if the sensors just can't be moved, then consider going with a diffuse (depending on the situation), Diffuse sensors don't use a reflector so they can't be tricked halfway through a part passing by unless there is a hole in something, but then it wouldn't matter because a retroreflective would also fail here too (which is why pallet sensing applications usually have sensors aimed at extreme angle where there are no gaps in pallets).


try some physical fixes before swapping to a whole new style sensor, it might work.
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Old September 23rd, 2022, 05:41 AM   #8
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We have used ultrasonic sensors in an area where we detect products which are sometimes black. Something like these but there are cheaper brands.

https://www.pepperl-fuchs.com/global...s&prodid=39276
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Old September 23rd, 2022, 08:22 AM   #9
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Quote:
Originally Posted by BradleyAllen1 View Post
The retroreflective eye is causing some issues with reflective tape on boxes so i want to eliminate this problem.
A through-beam sensor does sound as if it the simple solution you are looking for.
There are other methods, but if you have the possibility to install a trough-beam, then that is what I would recommend. There are millions of these out there working in environments with reflections, false light sources etc.
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Old September 24th, 2022, 05:19 AM   #10
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Yes through beam is definitely the answer, done this many times, we have had some really interesting ones.
Called to some conveyors where they were having problems with intermitent triggering of photocells, seemed weird as the cartons were not reflective but often detected no carton when there was one there, turned out to be a forklift yellow beacon triggering the photocell as it went past.
Had the same thing on some light curtains, took a couple of trips to find out what it was, just happened to notice it occured when a forklift passed the machine, solution some cardboard taped to the guard cage, after all, it was a cardboard box manufacturing company, not sure if they ever replaced it with something a little more aesthetic.
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Old September 24th, 2022, 12:51 PM   #11
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I had a similar situation on a reflective photoeye.

A table rose with a stack of circuit boards and interrupted the beam to the reflector, then the machine grabbed the top one and took it off.

The problem was some boards were electroplated after a conductive coating was applied to the inside of the hole - AND the outside edges. On those the sides got plated with very shiny copper.

The photoeye was suddenly reflected of the shiny edge and didn't go dark.

I ended up having to change the machine to a prox above to sense up.

Another problem with photoeyes was the shop was changed from mercury vapor highbay lights to all LED's and the new LED light would trip and hold on any photoeye it shined on.
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Old Today, 07:35 AM   #12
roxusa
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I went with through beam when we started running product in plastic wrap. Since you have the M12 connector simply attach a T splitter to it and a short cable back to new through beam (receiver) and another cable off splitter to the (emitter)
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