Ultra sonic?

Can you give us a better idea of the setup? Is the sensor looking from the side? Are all books the same size? Same orientation? What rate are they coming through at? What is the normal (acceptable) spacing?

As much detail as possible is good for getting people to take an interest, and start thinking about what's going on, and what may be going wrong.

Including a drawing or photo is good if you can run to it.

you can also use opticalelectronic sensor to do it.

Why ultra sonics? Don't get me wrong --they are great.

Is this a digital input to a PLC? Or analog?

If you are looking for a hieght of books, why not through beam eyes horizontally, or if the books are standard, a physical whisker switch?

Like CNpower said is a electric light-sensor not usable like a photo-sensor.

How sensitive is the ultrasonic sensor to background noise? (electric and sound)

maybe you have to set it's sensitivity different By a circuit or by settings.

PS my 500th post

This machine makes books for school children "exercise books" the sensor is mounted above the books as they pass through at about 40 a minute just before a trimming guillotine.Sometimes the books pile up and i want to stop the machine when this happens.A book is about 8mm thick and they pass the sensor with about a 200mm gap between.I have mounted it about 400mm above the books.This sensor has a teach in method .First teach without books onto a flat surface then teach 2 books high for the detection.

I'd suggest getting the sensor closer - 8mm (the incremental difference) in 400 is not a lot - especially with (as you say) lots of vibration around.

You might try teaching with one book as OK, and 2 for stop - you'll be less likely to get false triggering when only 1 is present.

So teach with only one book at the A2 setting. Splits the difference and will probably now be taught in the way you desire.

Which type(& brand) are you using? i am not familiar with it and i do not know if the paper absorbs some of the ultrasonic energy

Hello darren221170:

You are talking of a collator/stitcher/trimmer, I think.

I worked one and it had two infra-red sensors. One on the three knife trimmer, the other, as the books went from horizontal to vertical when they fell onto the grabber which took them through to be cut. Ours was on the machine as was several touch sensors to stop the machine when there was a jam and, to stop you getting your figures cut off!

I assume you got your second hand and useful bits like sensor have gone?

I was chatting for a long time with Digi-Key and I send you the discussion on PM hope you do not mind.

These are the type of sensors you want.

Optical/electric. Look for part # OR547-ND.

This was on the list on the link above. It works at about 300mm. The 'part' comes as a pair, one with the infra red light, the other with the receiver.

There is other sensors which may be of use on the links below. I also have included to chat I had with the technicians and sales at Digi-Key. Please forgive me if this is not what you want.
http://media.digikey.com/photos/Omron%20Elect%20Photos/E3S-AT61.jpg

Take care and good luck!

If you go to the Digi-Key site you can chat and ask the technicians stuff.

Let me know what happens please?