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Optocoupler symbol?

Discussion in 'General Electronics Discussion' started by toddarc, Apr 17, 2016.

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  1. toddarc

    toddarc

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    Mar 5, 2014
    Can anyone identify this symbol for me? Looks kind of like an optocoupler but without the light rays... The lathe controller I bought shows these pretty much everywhere input/output signals are connected.

    Thanks!

    symbol_question.jpg
     
  2. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    It is an opto-coupler. No need for lines to indicate light transfer from the internal LED to the photo-transistor. Does it have a part number? Here is a page with many images of opto-couplers, most with arrows indicating the optical emitter, but some without. The function is obvious from its application.
     
    toddarc likes this.
  3. toddarc

    toddarc

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    Mar 5, 2014
    Thank you for the reply. There is no mention of the optocoupler in the manual or part number for it. I figured it must be some sort of isolation device but wasn't running across that exact symbol anywhere.
     
  4. Minder

    Minder

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    Apr 24, 2015
    The ULN2803 is a buffer driver, the opto is most likely a slot opto or retro-reflective type.
    Although the symbol is more representative of a slot type.
    There should be a 'flag' for a slot type or a reflector for the retro type somewhere on the M/C where they are triggered..
    M.
     
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  5. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    Good observation. I didn't notice he said "lathe controller" so these devices probably do act as sensors, typically as safety interlocks but also perhaps as limit switches. A hacker would probably disable them to get on with the real business of removing stock in the lathe.:rolleyes:
     
  6. toddarc

    toddarc

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    Mar 5, 2014
    The controller is a chinese 3-axis with a manual that assumes a fair amount of previous experience I think ;) From what I'm gathering, the individual components outlined mimic an opto isolation board like this one:

    http://www.ebay.com/itm/270630189789?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

    The manual outlines the optocoupler circuits with similar resistor values/placements. It also outlines the use of darlington transistor array for tool changer motor contactors, and as Minder pointed out - buffer drivers for encoder communications. Am fighting through this slowly, is just a learning curve. The manual mentions the use of their interface boards but there is no images of them or drawings. Most of the pins for outputs on the controller call for 0v availability, so am thinking they close to provide the ground for the internal led in the optocouplers (low signal) and require a resistor to the 5v source as a means to control current flow. I attempted to attach the pdf for anyone interested, but the file size is too large. I'll just keep picking away until it all makes sense to me.
     
  7. hevans1944

    hevans1944 Hop - AC8NS

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    Jun 21, 2012
    So, I guess they are just opto-isolators. I do this any time I have to interface "real world" signals to expensive electronics, both for inputs (to the LED half) and for outputs (from the photo-transistor half). The use of a Darlington connection is usually required to actuate relay outputs, but more common is the buffer-driver @Minder mentioned, many of which are designed to drive low-voltage relay coils. The Inboard DC Opto Isolation 8 Input Channels board looks like it is built like a BSH. Very high quality from visual appearance. And of course eight four-lead optical isolators are visible on this board. Is there a complimentary board for doing isolated digital outputs?

    Sounds like a fun project. Please let us know how it turns out, hopefully with some nice photos!
     
  8. Minder

    Minder

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    Apr 24, 2015
    What is the nature of the controller? Mach3 or Chinese special, the latter is known for almost zero documentation.
    Most hobby machines use these sensors for home or over travel limits.
    BTW most of my job is CNC retro-fits for a living.
    M.
     
  9. toddarc

    toddarc

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    Mar 5, 2014
    whoa, that's pretty cool that this touches into your day job!

    It's a chinese special. The documentation seems fairly decent - but again, I think it is geared towards OEM usage where people do this every day. I'm hoping this machine is a step up from hobby when completed. It is a mix-and-match of components but the gear head is driven by a 3hp vfd-driven motor and although I'm waiting for the servo motors to arrive, the matching drives are already here. I'll have around $3500 into it (cross my fingers) when completed (before tooling), but am hoping for some serious precision capability as opposed to buying a worn-out machine for the same money. I had looked at Mach3 but by the time a person buys everything (forward compatible with mach4) plus software the $600 I spent on the controller seemed reasonable. I might have gone with mach4 had it been more developed and proven.

    I've been a maintenance mechanic for maybe 15 years now. However, the system design has always been implemented long before I happen upon a machine. Years ago I remember changing out an optocoupler or two on an isolation board of sorts but now much of that experience is coming back in "Ah-ha" moments as I pick through this project. Hevans1944's last post caused another one as he talked about "(to the LED half) and (from the photo-transistor half)". Although kind of vague, the manual does show the optocoupler orientation to the controller reversed from input to output (photo-transistor leads hanging out over the cnc side for inputs as opposed to the output picture above).

    Am working this weekend, but will throw the manual pdf on my web server space and provide a link in a day or two so more of what I'm referring to makes sense.

    Thanks!
     
  10. toddarc

    toddarc

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    Mar 5, 2014
    Here is the pdf link if you guys are bored and want to take a peek.

    http://www.preventativemaintenanceconsulting.com/misc/NEW990TDb.pdf

    I'll be working on mechanicals in the short term and will be ordering some of the electronic components so that they'll be here when that phase begins.

    Thanks for steering me in the right direction!
     
  11. Minder

    Minder

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    Apr 24, 2015
    Interesting.
    What kind of command is does it use for the servo drives?
    ±10vdc or step/dir?
    There must be a parameter page for set up for encoder resolution etc?
    Too bad the display is cluttered with Chinese symbols.
    M.
     
  12. toddarc

    toddarc

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    Mar 5, 2014
    The servo drives are pulse/dir and the spindle(s) are 0-10vdc with encoder feedback. The manual talks about assigning the third axis as rotary or linear so am wondering if that could be set up for a servo spindle to allow things like gear hobbing etc., but have only lightly read through that section and am a long ways from entertaining that notion.

    I remember seeing something about "Spindle Encoder pulses X 4" in a setting or two while thumbing through the manual. Am not sure why you multiply by 4 but you are able to enter encoder resolution. I noticed even gear ratios can be specified for gearhead so with a bit of messing around it would even be possible to have the controller shift gears for different applications. Not sure how much gear shifting I'll need to do with a vfd but thought it was interesting.

    I received the "English version" with standardized buttons and display. I have noticed broken English in some of the referenced screen interactions but am hoping it will be little more than a minor convenience - we will see...
     
  13. toddarc

    toddarc

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    Mar 5, 2014
    I have 1 more hurdle... I'm having a hard time wrapping my mind around the servo drive hookups to the controller. The controller has TTL connections but the drives are able to connect to many different signal types. If someone has a moment, could you take a peek and give educated input? The drive signal info starts at page 57 here (actual drive is MR-J2S-10A):

    http://dl.mitsubishielectric.com/dl/fa/document/manual/servo/sh030006/sh030006j.pdf

    and the controller signal info starts at page 91 here:

    http://www.preventativemaintenanceconsulting.com/misc/NEW990TDb.pdf
    I will be running overtravel signals through the controller so really all I am looking for are the actual TTL connections for step/dir.

    For those interested, here is a pic of my project today:

    lathe_7_11_16.JPG


    Turret is just setting on top as I was getting a rough idea for height. I'll be setting up for gang tooling for the short term.

    Thanks for your help!
     
    Last edited: Jul 11, 2016
  14. Minder

    Minder

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    Apr 24, 2015
    The encoder resolution x4 means that the drive is capable of using all 4 edges of the quadrature signal to increase the basic encoder resolution x4 this way.
    Are you using this drive for a spindle? the input appears to be 10vdc analogue.
    M.
     
  15. toddarc

    toddarc

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    Mar 5, 2014
    No, am using a VFD for the spindle that can utilize the analog signal - paired with an encoder. I'm using the Mitsubishi drives for the X and Z axis'. I am just not familiar with the differences between types of signals used for Servo Drives, and am not sure what the voltage requirements for the signals are. And, it appears the Chinese and Japanese use different letters to define the function of the pin connections so that is complicating matters. I broke down and ordered a motion control book on Amazon tonight as this appears to be a huge hole in my knowledge as a maintenance mechanic. Is easy to replace components on a system - but harder to configure from scratch...

    Thanks Minder!
     
  16. Minder

    Minder

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    Apr 24, 2015
    Those are nice drives but a little overkill for a first project, also the controller appears to use step/direction means of control which the Mitsubishi drives may not have, at least I could not see it in the manual, also you need a program to configure the drives up by parameter etc.
    M.
     
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