Need Help With A Rotary Encoder

Discussion in 'General Electronics Chat' started by diebog, Apr 12, 2013.

  1. diebog

    Thread Starter Member

    Mar 23, 2013
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    Hi all, There is a rotary encoder on a piece of equipment I have which is a Granite cutting bridge saw. The encoder is used by a TouchWin display (like this) panel that lets the user input a dimension and it will cut that size. What I am looking to do is add a separate display that I can tie into the encoders output signal and be able to have the display readout inches as the encoder moves. Also need the ability to zero out.

    The TouchWin probably could be programed to do so, but I have no clue how to do that, so I just want to add a simple single DRO with zero capability to read the signal. The encoder is an OMRON E6B2-CWZ6C.

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    Last edited: Apr 12, 2013
  2. BillB3857

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    Almost all digital readouts I've seen are in decimal, not fractions. If you want fractional, I think you are moving into the realm of a microprocessor to take in the counts (600 per revolution on your encoder), the pitch of the lead screw or gear ratio of the drive, do the math to convert counts to distance and format the display for fractions.
     
  3. strantor

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    Oct 3, 2010
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    For this I would use a red lion panel meter (counter). I specify a brand because that's what I'm familiar with and confident will work; other brand may work, possibly even dirt cheap Chinese counters on eBay. Check out the redlion.net website and look at their scalable counters (specifically, look at the Gemini model) for an idea what you need.
     
  4. diebog

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    Mar 23, 2013
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    Thanks for the input strantor! Forgive me but I am a newbie and may need my hand held a little. lol.....so will this display be able to count out in fractions like I wanted? I would also like to be able to program it to delay "X" amount of revolutions to equal blade width when the zero "reset" button is pressed. So basically, say a cut is made, the saw motor is switched off, and is still in line with the cut. I want to be able to manually move the bridge on either side of the cut say 4". I need the computer that reads the encoders input to wait the number of revolutions to equal the 1/8" or so blade thickness. This of course will be trial and error to get it to cut exactly the correct dimension by playing with the negative revolutions it needs to subtract from the equation. An example that I can think of is a digital dial caliper. Some have the ability to count out in fractions, decimal mm and sae. These use an mini rotary encoder don't they?

    I would like to be able to build this myself, but haven't had any schooling in this field. Im guessing ill need some type of a processor to convert the signal to fractions, as Bill suggested.
     
    Last edited: Apr 24, 2013
  5. strantor

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    I missed the part where you said you wanted to read out in fractions; actually I don't see it at all. Apparently Bill saw it, but I can't find it. Weird.

    Anyway, no, I haven't seen a counter that will count inch fractions. They do it in decimal (.125 vs. 1/8) which is less confusing IMO. There may be such a counter but I haven't seen one and I doubt that it exists. If you absolutely must have the fractions, you're probably going to have to design that yourself and it would probably be a massive undertaking for you. Or you could just put a conversion chart next to the display.

    It seems to me that you could get around this problem simply by choosing which side of the blade to designate as your reference. But that comes dangerously close to me telling you how to do your job, so I'll focus on your request.

    Having a read through the Gemini 4000 manual, I see this, which seems to match the description of what you want:
    Have a look also at the detailed description of the Counter Load Function on page 5 of the manual. You would need to enter the width of the blade again every time the unit loses power, as this is not a stored value.

    The best deal I can find on the gemini is $200
    If you were an electronics engineer with a bench full of all the components and tools needed, you could probably design your own system for cheaper (as long as you don't bill yourself for your time). But I get the feeling this does not describe you. You would probably spend much more than this (especially if your time is worth anything) to try and build one yourself.
     
  6. diebog

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    Mar 23, 2013
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    Ya sorry about the fractions part. I accidentally deleted part of my original post that bill saw when I edited it.

    The need or want for fraction display is more or less for ease of use for other users on the saw. I write and measure in fractions all day long and that's what terms are used most in the construction trade. Having an conversion chart would maybe be a possibility if nothing else will work. Just no were really to display on the type of saw I need it for and the time spent trying to convert to 16ths 32nds 64ths etc would kind of be a hassle. Decimals like .25, .5, .75 would be fairly easy to remember its just not ideal.

    Just about most digital dial calipers will read out in mm, decimal and fractions. It has the ability to zero out as well. So why is finding a display for an encoder so much different? I thought there would be a plethora of options but guess I was wrong. Ya your right, enginering something like this is not something I could do, I was more or less referring to assembling the components if someone could tell me what to get and such. Meaning it densest have to be a turn key deal, but I would need allot of help with the technical stuff.

    And I would need something to retain the blade width measurement because entering it every time could prove to cause many problems if forgotten and a cut was made thinking the blade was subtracted. I would also need it to be able to subtract the blade width value moving forward as well as the bridge of the saw moving back. Some tines a cut is made and you have to make the second cut from the backside of blade and others you need to move forward to cut. Granite slabs are heavy and usually remain on table and the saw is moved around the granite. The table does rotate, but again rotating when a cut needs to be one way if the display only accounts for blade width the other way could cause problems.
     
  7. strantor

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    It sounds to me like you are going to need a purpose-built solution. I don't know of any generic out-of-the-box products that meet your requirements. You might look into machine tool DROs like for a milling machine. I have never used one but I believe they can be set up to account for tool kerf. They are used usually with linear glass scale encoders, but I suspect that the output of the rotary encoder would be the same. Not cheap though.

    You mention digital calipers, which reminds me of the "poor man's DRO" which is just a modified digital caliper permanently installed on a machine (see pic). You may be able to implement this fairly cheaply and get your inch fractions. You would just have to keep track of your kerf; possibly write down the width of the blade, move to desired location and zero, then move additional width of blade and zero again, then cut.
     
  8. strantor

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    It's late and I'm sleepy so this next idea might not be as great as it seems, but...

    Follwing on with the poor man's DRO, for your purposes, you might be able to build it in such away that it automatically subtracts the width of the blade, by mounting it rigid on one end, and on the other end mount it in such a way that it can slide back and forth a limited amount; possibly by milling a bolt slot that is the exact width of the blade. This way, you begin to move the blade but the caliper does not begin to count, until you have moved exactly the width of the blade, then it runs out of room in the slot and begins counting. You should be able to make this work going in either direction I think.
     
  9. BillB3857

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  10. diebog

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    Mar 23, 2013
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    Possibly, but how would I get it to read my encoder's signal?
     
  11. strantor

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    WOW! I'be spent probably a whole cumulative day on that website in the past year, and never ran across these nifty little DROs. Thanks!
    You wouldn't. Looks like the same thing as a digital caliper, but with brackets. An "official" poor man's DRO.
     
  12. BillB3857

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    Google is your friend, Stantor! Key was "digital readout with fractions"
     
  13. strantor

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    I guess I was burdened by my own notion of how it should be. See, I've been planning to make a DIY DRO for my lathe for the past few months. I have a 2048PPR rotary encoder and one of those red lion counters already. I just didn't have time. So when OP came in asking for something so similar, I was already thinking inside the box I'd made for myself. I was googling things like "panel meter counter fractions".
     
  14. jordan_dear

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    Apr 29, 2013
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    hey frnd you just need to measure incoming pulses from that rotary encoder,and it should be consider by u that hw many pulses for particular size of length according to this observation you write a micro controller programme.
     
  15. diebog

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    Mar 23, 2013
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    That sounds great, but one problem.......how do I do that? lol I know nothing about programing.

    Another possibility is to find out how to program the "touch win" display/panel that the encoder is currently being used by. I have accidentally stumbled in to a screen with options that looks to do with programing, but all the damn options are in some sort of Chinese or Japenese symbols. I dont know how to go about decoding it into english or where to find a user manual for it.
     
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