Re: [beam] Re: Lasers
- I think when you say unable to use anything like a microcontroller or PLC you are sort of mixing things up and making life difficult.A PLC generally is a box of electronics and never cheap.A microcontroller on the other hand is just a chip and (if you choose the right one) is as cheap and as hard to use as an LED.Whereas one time you might have used a 555 timer (for example to generate a 38KHz signal) it is now easier to use a microcontroller chip.And since this is Beam, you should understand freeforming so you wouldn't even need a PCB.----- Original Message -----From: WilliamSent: Monday, November 07, 2011 2:10 AMSubject: [beam] Re: Lasers
To add on to the below statement, when i said "unfortunately i am unable to do that at this point" about encoding i was referring to that i am unable to use anything like a microcontroller or PLC at the time. I am defiantly going to see if i can work in that idea some way of using the cap.
--- In email@example.com, William Koepp <william.koepp@...> wrote:
> Mr. Buckley I do apologize for my mood. The way i came off was not intended, i am just stressed with this project. Mr Dumse a encoded signal was my original thought but unfortunately i am unable to do that at this point. I do greatly appreciate everyone that did comment and help. All of you guys are intelligent and experienced and that is why i come to y'all. I have decided to go with lasers and will just have to cut back somewhere else on the project, as things progress in the project i will update y'all if you like and any future comments i will be more welcoming of and less apprehensive.
- Yes i am unable to use micro's. For some reason my professor seems against them and is all big on PLC's, especially Siemens made ones. I am unable though to use a PLC because we have none to spare and as you said they are costly. I am really going to try and push the topic of using microcontrollers for this do to the added safety it can provide. I have yet to work with any true PLCs myself, so in your experience would it be easy to wire a PLC to the picaxes if i am able to go with those? We will eventually add a PLC into the system. To the freeforming, well i am ok but far from great, we have some perf/proto board on hand i think so i might as well use it.
- Seems as if your professor is living in the last century or at least fondly imagining that he is teaching you the way 'industry' does it, Buy some equipment, wire it together and hey presto you have your system. In that case instead of designing a light curtain he should be insisting you obtain items off the shelf to create your curtain.Why would you wan to wire a PLC to a PicAxe? See later.I suggested you generate a 38KHz signal to drive an IR-LED, you can't (or at least you couldn't) do that with a PLC. In the past you would have used a 555 timer IC or similar to generate the signal which would of course depend on the stability of the resistors and capacitors used.Nowadays it is easier to use a singlechip microcontroller with an inbuilt oscillator and program a pin to output a 38KHz signal.I mentioned a PicAxe because they are easy to program and generating 38KHz output and signals to Sony codes is built into the language and they don't need a programmer because they have a bootloader. You could do the same with other small PICs or AVRs but maybe need to get programmers and compilers. Reinventing wheels is costly in terms of time at least. And if you are making a one-off who cares if the parts cost is 10c or 50c. Having generated your 38KHz IR beam a 38KHz detector IC would do all the work giving you a low for signal present and high for no signal. You could feed that signal into whatever latching circuit you want to use. It would be the output from that circuit you would feed to the PLC. Now the latch maybe another small microcontroller that is looking for codes in the IR stream for added safety. Again the PicAxe chips have that functionality (for Sony codes) built into the language.It depends on the PLC you use what logic levels it can read.You need to understand PLCs because that is what industry uses, they are very rugged and virtually bomb proof but it is horses for courses, you wouldn't try and clean your teeth with a yard brush.DAvid----- Original Message -----From: William KoeppSent: Monday, November 07, 2011 3:59 AMSubject: Re: [beam] Re: LasersYes i am unable to use micro's. For some reason my professor seems against them and is all big on PLC's, especially Siemens made ones. I am unable though to use a PLC because we have none to spare and as you said they are costly. I am really going to try and push the topic of using microcontrollers for this do to the added safety it can provide. I have yet to work with any true PLCs myself, so in your experience would it be easy to wire a PLC to the picaxes if i am able to go with those? We will eventually add a PLC into the system. To the freeforming, well i am ok but far from great, we have some perf/proto board on hand i think so i might as well use it.
- Hahaha yeah he does do the "when i was in the industry..." alot. The reason i asked is because he wants to get rid of the adept controller it has and wire it to a PLC sometime next year, which i dont understand because we are about to put a brand new $4k DEPS board into the controller. I just try to do as he asks and keep a good GPA. I will be taking a PLC course but it is not for another two semesters i believe.
- William said: Sunday, November 06, 2011 8:10 PM
> When i said "unfortunately i am unable to do thatMaybe I'm too long winded in my replies. Seems you've missed my
> at this point" about encoding i was referring to
> that i am unable to use anything like a
> microcontroller or PLC at the time. ...
> I am defiantly going to see if i can work
> in that idea some way of using the cap.
Let me make it simple.
Get an IS471F and a matching IR LED. Put the IS471F on one side
of the opening. Put the IR LED (via wires run on the floor or
elsewise) on the other side.
You can get ~9" detection doing this as an IRPD, but straight
on, as a break-beam it might go quite a bit further. Then you
have your encoding, already built in. The IS471F provides the
drive to the LED, and that drive is encoded. Then inside the
IS471F is the whole circuit that checks incoming IR light for
that encoding. Very simple. Very cheap.
If you don't get the range you want (testing is called "an
experiment", useful in your learning) you can extend it by
putting the LED and the detector at the focal point of a lens.
Probably cheaper, you could use a laser for the IR LED. Or use
the similar S6986, and use a visible laser. Only a little more
expensive, but is much easier to get lined up.
There's your whole project. Output is a open collector to GND to
signal something in the beam.
- Thank you Randy for the idea. I am going to try to use a Picaxe or 555 timer though. we have the 555's on hand. Yes i think your reply hand gone a bit over my head, and if i tried to explain it to the others, who have even less understanding of electronics, it would def go right over there head. I will keep your idea's in mind though because situations are constantly changing. I have my proposal in about 30mins, so i will find out what is excepted and what is not.
- " If you put a DC blocking capacitor in line with the
signal, no matter if there's a little steady ambient light, or a
lot of steady ambient light, the output of the cap is 0V. DC
does not pass through a cap. However, if the signal is modulated
with a higher frequency, the signal appears at the output of the
cap, because caps pass the AC component riding on a DC signal
level, while blocking the DC from passing. "
A basic lesson.
use simply solutions, a capacitor, a crystal (32.768 kHz) or ressonator (445kHz) and a watch-dog.