ThruBeam

Scott_Corriveau

Member
S
Join Date
Feb 2014
Location
USA
Posts
7
Hey Guys


This one i have never done before how you guys might have an idea.

I have a thrubeam normally open when object passes through close relay. No biggy. But i want to ignore high speed items and detect low speed items. Plc is a clic and it doesnt have many options.

Thanks Guys
 
Are all the items the same size ?

Do you have to detect them immediately after the trailing edge ?

If they're all the same size, you just use a timer. When the through-beam is blocked for more than X milliseconds, that's a "low-speed" object and you can use the "Done" condition of the timer in your logic.

If they're not the same size, well, that becomes a much more challenging application.
 
Simple input "debounce" application. Do a search for this term and you'll find many examples.

Instead of your input turning on an output, or whatever else it needs to do in your sequence, make it start a timer and use the timers done bit to trigger the output or rest of the sequence.

Adjust the timer value high enough so that it ignores your high speed items and catches the low speed items.

Edit: Beat me to it Ken... checked your PM's lately, btw? :)
 
Hey Ken

2 different sizes and 2 different speeds.

Scott


Ken Roach said:
Are all the items the same size ?

Do you have to detect them immediately after the trailing edge ?

If they're all the same size, you just use a timer. When the through-beam is blocked for more than X milliseconds, that's a "low-speed" object and you can use the "Done" condition of the timer in your logic.

If they're not the same size, well, that becomes a much more challenging application.
Click to expand...
 
More information gets you more participation in the thread and better answers.

What are the sizes ? What are the speeds ? Are the speeds known ? Are they changing ?

Maybe this is what you're hinting at: an object that's 10mm in length moving at 1 meter/second will block the photoeye for the same amount of time as an object that's 20mm in length and moving at 2 meter/second. That would make them indistinguishable using a single sensor.

Calculate the time each size and speed of object will take to pass the sensor, and you will clarify the problem.
 
Fell Asleep

Hey Ken

Sorry i fell asleep on the couch.


ok sounds stupid. I have a ball about 5 inches in dia and a shoe on a foot. Yes this is a foul light system for a candlepin bowling alley.

Balls can travel upwards of 90 mph need to block that input and only pickup the foot if it passes foul line which is a though beam.

Scott


Ken Roach said:
More information gets you more participation in the thread and better answers.

What are the sizes ? What are the speeds ? Are the speeds known ? Are they changing ?

Maybe this is what you're hinting at: an object that's 10mm in length moving at 1 meter/second will block the photoeye for the same amount of time as an object that's 20mm in length and moving at 2 meter/second. That would make them indistinguishable using a single sensor.

Calculate the time each size and speed of object will take to pass the sensor, and you will clarify the problem.
Click to expand...
 
Raising

Hey Uptown


Wish i could but i can not. has to be down with some type of speed filter. And Clic PLC is very limited. Looking for a down and dirty ladder logic to do it.

Scott




uptown47 said:
Can you raise the sensor up so that a ball would pass under it but a persons leg would trigger it?
Click to expand...
 
Well, with one sensor, your only option is timers but I can't see it being particularly reliable to be honest. Some people bowl slow (kids), some fast.. etc. Also the bowl and foot could cross the line together etc?

Maybe 2 sensors and then you would be looking at the order in which they come on and off to determine direction and therefore a foot crossing the line (i.e. a foot would travel back towards the bar, a bowling ball would only travel towards the pins). ;-)
 
League Play Only

Hey Uptown

They only turn these on for league play so slow bowlers are not an issue. most of the pros are pretty fast. My biggest problem is the software limits only have one style of timer on delay or off delay

Scott


uptown47 said:
Well, with one sensor, your only option is timers but I can't see it being particularly reliable to be honest. Some people bowl slow (kids), some fast.. etc. Also the bowl and foot could cross the line together etc?

Maybe 2 sensors and then you would be looking at the order in which they come on and off to determine direction and therefore a foot crossing the line (i.e. a foot would travel back towards the bar, a bowling ball would only travel towards the pins). ;-)
Click to expand...
 
It's just going to have to be an on-delay timer then. You'll have to experiment. Try setting it up for 400ms and see if the bowling balls trigger it. And then adjust accordingly. Obviously, if the timer comes on then sound the alarm/flash a light/squirt the offender with red dye etc etc... whatever the rules are. ;-)
 
I’m not an avid bowler and had to Goggle candlepin bowling. I would be lucky to break a 100 with bumpers but I would think that you could place the sensor low enough to pick up a foot just across the fowling line with a timer preset at say .5 – 1 sec and see what that gets you. You asked for down and dirty. FYI – I have never used the Click
I would think that the bowlers would try to get as close as they can to the foul line without going over and if this is the case I don’t envision the small 4.5” ball being in the same area as their foot. If they do release the ball before the foul line I don’t see that small of a ball blocking the sensor for that amount of time.
 
Candlepin

Hey Bob

yeah i know but the bawl play feild includes the approach so there are allowed to release ball before foul light beam this is why i need to filter it.My biggest problem is forgetting how to do stuff maybe one or two programs a year and clic which is very cheap just doesnt have the capablities that i am used to on siemens.

PS candle pin is a northeast and canada thing but its fun.

Scott



Bob O said:
I’m not an avid bowler and had to Goggle candlepin bowling. I would be lucky to break a 100 with bumpers but I would think that you could place the sensor low enough to pick up a foot just across the fowling line with a timer preset at say .5 – 1 sec and see what that gets you. You asked for down and dirty. FYI – I have never used the Click
I would think that the bowlers would try to get as close as they can to the foul line without going over and if this is the case I don’t envision the small 4.5” ball being in the same area as their foot. If they do release the ball before the foul line I don’t see that small of a ball blocking the sensor for that amount of time.
Click to expand...
 
Scott,
If my quick rough math is correct even at half speed 45 MPH = 66 fps and if the sensor was placed at a height to pick up the diameter of the ball which is about .33 ft in diameter, the ball would only be in front of the sensor for .005 seconds. I would try the Timer On instruction set at .5 – 1 sec preset and if the timer times out you have a foul.
 
put the sensor as low as possible, then the timer on about 0.2 sec or like bob says even o 0.5 to 1 second.
the loop time is not very important anymore as the foot is never able to take away under this 0.2 second.
probably there are rules for this.
 
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