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IndustryArena Forum > CNC Electronics > Stepper Motors / Drives > Is necessary to use a breakout board?
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  1. #1
    Join Date
    Apr 2007
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    16

    Question Is necessary to use a breakout board?

    Hello everybody:
    I am trying to get in in the retrofits cnc machines with steppers, and I am looking several web pages, some of them sell different kind of drives and some of them too, sell different boards like breakoutboard, charge pumps and modio boards.
    Can somebody tell me the specific use of these boards?
    It is necessary to use them?
    rolveram

  2. #2
    My understanding is that it would be possible to go without, but really, that's a bad idea.

    A lot of the boards will give you visual feedback (dasblinkinlights) of what is going on, and make it far easier to make changes and fix problems.

    As for which one you should get, I don't know.

    -Jeff
    www.JeffAlbro.net/cnc/

  3. #3
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    Apr 2007
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    16
    Thank you for your advice. But someone else can tell me what are for?

  4. #4
    Join Date
    Apr 2005
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    3634
    http://www.campbelldesigns.com/breakout-board.php


    The PC parallel port break-out board was developed by James Cullins. James is the owner of Sound Logic in Grapevine Texas. The picture is of Rev level 1.8A.

    The question that I get asked once in awhile is: Why do I need a break-out board? The options are, solder directly to a DB25 connector. I have done this and it creates a lot of wiring that is hard to manage. The next option is to buy a DB25 to terminal strip converter board ($35 to $45). The converter board is a lot better than soldering directly to a DB 25 connector.

    Both option have their drawbacks which are addressed with the features in a break-out board.

    The first and very important feature is isolation. The break-out board provides total optical isolation of the parallel port from the power supply and the equipment being controlled. If high voltage is inadvertently applied to any lead on the parallel, it most likely will burn out something inside the PC. With the break-out board, the parallel port is isolated. Voltage can burn out parts in the break-out board, which can be replaced.

    The break-out board was designed to interface to the Gecko drives and inductive proximity sensors or standard micro switches. In the case of the Gecko drives, the board provides the 5 volts needed to power the optical isolators in the Gecko drives. The board also has a switch that will allow it to interface to other drives that want the ground connected to the PC ground.

    The break-out board has screw terminal for all signals. In most cases, a led is also present on most lines.

    The break-out board contains three power supplies. One 5 volt supply is used to provide 5 volts to power the optical isolators in the Gecko drives. A 12 volt power supply is provided to supply power to the proximity sensors. A second 5 volt supply is provided to convert the output from the proximity sensors back to 5 volts before it is sent back to the PC.

    The input connector is a 26 pin duel in-line connector. The 26 pin connector is connected (ribbon cable) to a 25 pin parallel port connector which would mount on the outside of your control box.

  5. #5
    Quote Originally Posted by rolveram View Post
    Hello everybody:
    I am trying to get in in the retrofits cnc machines with steppers, and I am looking several web pages, some of them sell different kind of drives and some of them too, sell different boards like breakoutboard, charge pumps and modio boards.
    Can somebody tell me the specific use of these boards?
    It is necessary to use them?
    rolveram
    Its necessary to use something! As to a breakout board I have a very mixed opinion; leaning towards not. What the key problem is; standard parrel port voltage is 3.3 volts on most PC's. Which is to low for signal transmission in a signal dirty enviroment. So you either need the B board or a card to take that voltage up to 5 volts.
    Ken
    Kenneth A. Emmert
    SMW Precision LLC
    Spokane, WA
    866-533-9016 Toll Free

  6. #6
    Join Date
    Dec 2005
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    390
    You could get by without a breakout board but be aware that any stray voltage could come back into your computer. Now, most likely, your computer will have isolation on the port itself. So, you might not lose anything, or possibly just the port, or possibly the computer itself.

    I have tried a few breakout boards and frankly have not been all that impressed. While yes they are providing the isolation their operation seemed flaky at best. Direct connections gave consistent results.

    If I was going the breakout board route again I would get the simplest one I could possibly get that provided isolation. I would also prefer one that required soldering instead of those screw down connectors but I've never seen that except in DIY designs.

  7. #7
    While some features that are found in breakout boards can be optional, some are not. The first and most important one is that signals that go Geckodrives MUST be buffered. A computer’s parallel port will put out only 10mA, and geckos require 16mA. Yes, I know that are thousands of people connecting them directly to the parallel port and for most cases they do work. The reason for this is because of the process capacity of how the optoisolators are made. So if you are planning a CNC system, you should not be counting on getting lucky, count on been reliable and safe.

    Not all CNC systems are the same and one solution does not fit all. While some features can be optional, some are not. This is my analysis:

    - Buffering: Required by most drivers because of the high speed optos they use. The parallel port was not really designed to power all the signals and wires that people connect to it. Buffers also provide a great deal of protection because these could act as fusses in case of a short.

    - Pull-down (or pull-up) resistors: Required. Wires connected can act as aerial antennas. Noise can get into the parallel port. Pull-down resistors forces the inputs to be HI or LOW.

    - External Enable Pin: Required. This is something I use in all the breakout boards that I offer. It is a terminal that requires +5vdc to enable the outputs. I always recommend to the users of my boards to connect the e-stop line using active hi with a NC switch, and then run a second line in parallel to the EN pin. That way when you press it, you no just send the signal back into the pc so the control software can stop the system, but you are positively taking all the outputs to ground and stopping everything.

    - LEDs. Nice to have. For new users it is priceless to be able to see all the signals.

    - Optoisolation: It can be required or optional depending on the system and the user. I have had users tell me that they could buy a replacement PC motherboard for the price of an optoisolated breakout board (rarely true). The facts around this are that there are a lot of non-optoisolated drivers that can handle internally currents of up to 2000 volts, that I think you would be better off isolating. Meltdowns can happen. The risks can come not just come from the drivers, but from wires in and outside the control box.

    - Safety Charge Pump. If you are running relays that drive motors or turn on things. You MUST use this, it is not optional. You have to make sure everything remains off while the control software is not in control.

    - Other built in features: On-board relays, analog outputs for speed control, etc… These are nice to have if you need them. They provide a cleaner and safer setup.

    You can get a breakout board with all the required features for under $30 the rest really depends on your system.

    Arturo Duncan
    http://cnc4pc.com

  8. #8
    Join Date
    Feb 2007
    Posts
    1
    In a perfect world a BOB is not necessary. But would you be happy to live in a house that did not have fuses or circuit breakers? Over time, this shortcoming will cost you dearly. Accidents WILL happen.

  9. #9
    Join Date
    Dec 2005
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    3319
    Better yet, don't run the BOB and wire directly to the DB9 or DB25 pin on your PC.

    HOWEVER, when/if you OOPS something (and you will), plan to toast the LPT port. If you're lucky and have a plug in one which can be replace, if you can find them anymore (call Jameco).

    BUT, most new PC's use built in ones on the M/B. If you have a M/B based LPT port, you then have the joy and expense of replacing the expensive M/B.

    How lucky do you feel and competent are you that you'll NEVER make a wiring OOPS with your external CNC circuits?

    Do yourself a favor: spend the money and get a BOB. Mr. Campbell's information is worth more than you an ever imagine.

  10. #10
    Join Date
    Dec 2005
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    390
    This probably is not worth mentioning at all given the bipolar nature of the current discussion... but... Sound Logic boards, sold by Campbell, were the ones that I purchased and had problem after problem. Bob was not able to help and referred me to Cullins who sent me on wild goose hunts. I spent more on breakout board stuff than I would have on a new PC. I have also had problems with the breakout board apparently not getting the signal to the Gecko and the current mill position falling behind where Mach3 thinks it is.
    I like the idea of isolation and may try one of the CNC4PC boards but looking at this from pure economics the Sound Logic boards were not a sound choice in my case.

  11. #11
    Join Date
    Jun 2003
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    3312
    Are they necessary, no. Does it make life easier, yes. Can you have a clean setup with out one, yes. Can you screw things up without one, yes. Can you screw things up with one, yes.............. Will optical isolation protect you, maybe, maybe not, depends on installation and fault issue. Anybody want to donate to my political ambitions. :-)

    Seriously while the q & a may sound flip, it's honest. I've seen some pictures of "professional looking" boards that provided a fault path the screwed things up royally. I've also seen opto boards wired to completely defeat isolation.

    Bottom line, figure out what components you are going to use, then decide.
    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com

  12. #12
    Join Date
    Sep 2003
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    1113
    If you want to connect more than 3 axes (thinking Xylotex here) thru a single LPT port, I have come to understand you'd need one. Apparently the 4 axis Xylotex board is set up a little differently. But then if you'd want to add a 5th axis to it - you'd need the BOB again. [Even though MACH2 and 3 pin out to support up to 6 axes.] Hope I'm making sense here.....
    Jim
    Experience is the BEST Teacher. Is that why it usually arrives in a shower of sparks, flash of light, loud bang, a cloud of smoke, AND -- a BILL to pay? You usually get it -- just after you need it.

  13. #13
    Join Date
    Dec 2005
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    3319
    In the early PC days, when the LPT ports were higher power, 5volt logic, things were a bit less touchy than they are now with 3.3 volt low power LPT's.

    In the early days, you could rely on the LPT to SOURCE current as they had a bit more "drive". However, now with the advent of low power LPT's, you're far better off purely SINKING current thru the LPT.

    Example: I have desktop PC's that use a dongle to protect my cam design software - it plugs into the printer port. These will run the dongle and a printer and whatever I hook up to them. I even have an analysis program that has a different dongle and the system runs with both dongles piggybacked, no problemo.

    Yet, on my laptop, the EXACT same dongles with the EXACT same programs will only run with 1 dongle. Each time I use the alternate program, I have to switch dongles. I can't even run the floppy simultaneously with the dongle (the LPT runs the floppy drive) as the thing won't power thru the dongle.

    When wired so as to SINK current from external signal sources and when and if properly buffered (some simple CMOS and/or TTL chips will suffice), you can READILY get the LPT to communicate with the outside world.

    HINT: get hold of the book "Real World Interfacing with your PC" by J.J. Barbarello (ISBN 0-7906-1145-7) for some good buffering and LPT interfacing tips.

    Remember: it is ultimately to use the LPT to SINK current from and not SOURCE current to external devices. Proper buffering is critical if you intend to "drive" anything with the LPT.

  14. #14
    Join Date
    Apr 2007
    Posts
    16
    thank you all of you. Now I understand better the exactly purpose of the BOB.
    rolveram

  15. #15
    Join Date
    Jul 2005
    Posts
    8
    OMG...! there are breakout boards that will isolate your parallel port from your drives out there!!

    haha all kidding aside
    i dont use em and i often wonder if i should but i always come back to the conclusion that "if it ain't broke why fix it" .
    actually i use very inexpensive drives for my mill/drill convert. i originally started to play with those cheap drives when i first got involved with automation using pic microcontrollers and steppers i guess i got tired of building dual H-bridges (bi-polar)


    Standard circuit to drive unipolar stepper motors with 5, 6 or 8 wires. Uses 4 IRFZ44's. Can be operated in free-standing or PC-controlled mode. Uses standard IC's: 4013, 4030 and 4093. Separate power supply to IC's. Full explanation provided.
    Price:
    per axis= $18.95 ...!
    some soldering required
    if in doubts cut it!.... if it is still too short ..don't give up! come back tomorrow and cut it again

  16. #16
    Join Date
    Jun 2003
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    3312
    Quote Originally Posted by NC Cams View Post
    In the early PC days, when the LPT ports were higher power, 5volt logic, things were a bit less touchy than they are now with 3.3 volt low power LPT's.

    In the early days, you could rely on the LPT to SOURCE current
    Come on NC, you know better than that. Old brain fog? (nuts) I thought I was the only one who got that. :drowning: Actually early PC's used TTL technology and the parallel port output was normally more like 3.6V(ish) due to the TTL totem pole output structure. TTL couldn't source much current (-2.4ma) but could sink 16 to 24ma. There was no specification though, and the LPT ports were done to drive Centronics printers. A 2.2K or 4.7K pullup to 5V, and 74LS374's were the "popular" data line drivers. Then came the IEEE-1284 specification and chips such as the 74ACT1284 came out to improve the high side drive a little (-4ma).

    So NC is correct on the advice to sink current with the output, not source.
    Phil, Still too many interests, too many projects, and not enough time!!!!!!!!
    Vist my websites - http://pminmo.com & http://millpcbs.com

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