Adding a photo eye to a line. Help Please!

I work in a brewery/contract packaging buisness and i need to add an eye to our line. We make an energy drink for a customer and it has a sleeve label on it. I dont know if anyone is familiar with this type of label, but it comes on a roll and is shot over the bottle then ran through a steam tunnel to shrink the label to the contour of the bottle. If the bottle has moisture on it the label will not go all the way down before entering the steam tunnel. If this happens, the label sticks up about an inch over the top of the bottle. That is what i would like the eye to see. If the bottle gets into our filler (24 head 2x vacuum Sasib), the excess label sticking up gets cought in the fill head and destroys it costing us about $200 bucks a whack and an hour of down time. The sensor doesnt need to see any color or anything fancy, just if there is anything sticking out the top of the bottle. When it sees somehitng, i would like an alarm to go off, or eventually have a pneumatic cylinder push the bottle off the line. I have some extra photo eyes around here. Im not sure if i need a whole new PLC to do this, or if there is an easier way to make this happen. I have an old Allen Bradley PLC (AB-PLC 5/20) with a handfull of I/O units on it that were not using. If anyone can help me get this started it would be greatly appreciated. It SHOULD be pretty easy, i think but im not sure. Thanks in advance.

I dont need to use the AB PLC, and quite honestly, would rather not. I COULD reporgram the PLC used for the whole bottling line/filler, but that seems redundant just to add a photo eye and an alarm. Is there any easier way to do this other than reprogramming the PLC?


Eric Noe
LiquidMFG

[email protected]

Spotting the plastic sticking up

There can be difficulties if the film is translucent. Sometimes this takes a special eye. In theory this should work. You might have to get a vendor to bring in some photo-eyes to test if the ones you have don't work. Sick and P&F are possibilities as well as AB etc. In a situation like this, I usually try to get a vendor to bring in an "expert" who has alot of experience to give me suggestions. Naturally you have to us discernment in taking their suggestions. Timing might be an issue as well. You might have to use two eyes one to check for the error and then another to trigger the ejection. I doubt you would have to get this sophisticated, but it is something to keep in mind.

thanks

At the spot the eye is looking, the film is white. I would rather not have to bring in a vendor. They get annoying, always calling and hounding you to buy more stuff. We have photo eyes at the shop (AB i think). I can hook up the eye, and siren, although, i dont know what i would need to trigger the siren from the P.E. Im not worried about timing. I just need the alarm to go off when the eye sees something. That simple. The whole pneumatic cylinder idea might come later. For now, this is all i need. An alarm that goes off as soon as a sensor sees something. There is a good 30 feet of conveyor until the bottle would enter the filler. Thats at least 5-10 seconds. There is someone usually standing in proximity to the stretch that will be monitored. There will be ample time to grab the bottle after the siren goes off. Thanks again.


Eric Noe
LiquidMFG

[email protected]

so are you looking to integrate your photo eye into the existing system, or do you just want to have a photo eye that sets off an alarm without the current system noticing and just rely on an operator to stop the machine?

Option A means you're gonna need to tie it in, most likely to the PLC and add a little logic, or possibly study the schematics and find another way to fool the PLC into stopping the process. Option B could be done with some good ol' fashion wiring and a decent time delay on photo eye.

as for the photo eye, if you have a clear shot accross the top of the bottle, i'd go for a transmit/recieve setup, or a retrorelfective setup. i'd avoid proximity eyes, because they have a hell of a time with translucent materials and can be more hassle than they are worth.

what model photo eyes to you have already?

Considering the color of the lable is white, I would opt for a thru-beam. (seperate transmitter & reciver. Dark = On. You need to latch the alarm with a self holding contact on the relay. A timer in series with the relay coil will then turn off the alarm after a few seconds or so.

A simple stand alone circuit would be like so...

 

|    photo eye       timer                     | 

+-----||--------+-----|/|-----------(relay)----|

|        relay  |                              |  

+---------||----+-------------------[timer]----|

|               |                    2 sec.    |

|               |                              |  

|               +------------------{audiable}--|

|               |                    alarm     |

|               |                              | 

|               +-----------------{indicator)--|

|                                   lamp       |    

|                                              | 

+--------------------------------|transmitter|-|

|                                | power     | |

|                                              |

|                                              |

+--------------------------------|reciver|-----|

                                 | power |  

 

As a general solution, I would suggest an analog photo-eye (TX-RX).

The photo-eye Transmitter (TX) and photo-eye Receiver (RX) would be positioned above your limit (top of the bottle). The TX-RX set would have to be tuned to present a signal as long as there is no interference. As the bottles are moving through, if your TX-RX sees something, then the output toggles and you have a problem.

Don't tune the sensors to be on a hair-trigger. Give yourself a little bit of slack for atmospherics and dust. (You don't have dust in this operation... do you?)

This will detect any kind of interference... color doesn't matter (Labels do change now and then, don't they?).

It appears that... deep down inside, you are afraid to deal with PLC code.

This is NOT a case of Re-Writing PLC code... only a case of modifying the code. Sooner or later, yer gonna have to do it! This is an easy thing to deal with. So, why not now?

Eric,

I would be easy to add one rung to your existing PLC. You would need one spare input for the photo detector, and one spare output for the alarm. Take the program below and change the addresses to spares on your PLC.

Eric.Noe said:

I dont need to use the AB PLC, and quite honestly, would rather not. I COULD reporgram the PLC used for the whole bottling line/filler, but that seems redundant just to add a photo eye and an alarm. Is there any easier way to do this other than reprogramming the PLC?

Click to expand...

Guys,

IF there is a spare input and IF a spare output, and IF he has the software, and IF he has the warewithall, then sure; he can use the PLC. However all Eric want's to do is bring it to somebody's attention. A simple hardwire relay and timer will do the trick.

If your budget allows it I would seriously consider a scanner that will measure the height of each bottle to a 1/4" accuracy. These scanners are available from "Banner" and are not to expensive. You will need an analog PLC card for the 0-10v signal.

For this application I'd stick with a transmit/recieve photoeye. We use the Sunx FX-301P and have had awesome results. Sunx makes some of the best fibers I've used yet (with my limited experience!) I've played with some of the banner photoelectrics (mainly the D10s) and was not impressed.
Another thing to think about is the flicker of the photoeye. You will want it to pull up a timer and use the DN bit to trigger your alarm.
If you have a PLC with spare I/O, by all means use it!

I agree with Elevmike, Terry, and Lancie1 on the following points:

Elevmike

"A simple hardwire relay and timer will do the trick."

Click to expand...

ON THE OTHER HAND...
TerryWoods:

"This is NOT a case of Re-Writing PLC code... only a case of modifying the code. Sooner or later, yer gonna have to do it! This is an easy thing to deal with. So, why not now?"

Click to expand...

Lancie1:

"It would be easy to add one rung to your existing PLC."

Click to expand...

BECAUSE...
1. You can prevent the bad bottle from entering the steam tunnel if the alarm hasn't been ack'd if it's tied into the PLC.
2. Relays/timers will fail much more often than a correctly wired PLC input/output.


I would say use a discrete thru-beam photoeye and hardwire it as Elevmike has shown. That will give an alarm if the eye becomes misaligned or dirty in addition to detecting a bad product. The analog photoeye is a good idea for a PLC input, because then you can monitor the condition of the signal and pre-empt dirty lens conditions...but this guy is not ready for that yet.

Eric...The best solution for the long term will be to tie it in to the existing PLC...This is an ideally simple thing to get your feet wet with...and we can help you through it.

just my 2 cents

Just imagine...

What if we had no restraints for money, time, and resources... This would be so cool, with a vision system and a small robot to extract the pieces...
Sorry, I'm back to earth....

Thanks for all the help guys. Here is a little more info so i can figure out what i need to do. The PLC that i have (AB-PLC 5/20) is not being used at all. We bout a lot of conveyor off an auction, 3 semi trucks worth, and it came with a PLC cabinet. We just needed a 100 feet or so woth of the conveyor, so we got it and they gave us the PLC also. The whole cabinet is not being used AT ALL. All of the terminal blocks, I/O units, switches ect. are not in use at all and have no plans to be (yet). The photo eyes that i would like to use are AB 42MBS-5100 ser B Photoswitch with a 42MTB-5000 base. These are the eyes that were originally hooked up to the PLC that i would like to use. Im going to use the PLC. My question is, what kind of cable/sofware is needed to write a small program in that PLC. We have RS/Linx and RS/Logix (DataHighway?) for our main PLC, although this one looks to be a bit older. I dont think it will be too tough, i can tackle any PC problem, but the whole PLC/Automation thing is kinda new to me. I have all of the hardware to make this work, eyes, power boxes, realays, PLC, I/O, alarm, pneumatics; i just need a jump start with the software/programming end of it. Thanks again. You guys rock.


Eric Noe
LiquidMFG

[email protected]

Just a guess...

But I'm thinking, they were suggesting using the EXISTING PLC for the line... NOT adding a complete PLC for one sensor and alarm... Surely you have Maint. people that connect to the existing PLCs if only just to keep there backups up to date... grab on of these guys add the logic that Lance gave you and then just add the wiring from the sensor and to your light/siren... I WOULD NOT USE A PLC SOLELY FOR ONE SENSOR........

Here is a pic of the P.E. I have.