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IndustryArena Forum > MetalWorking Machines > CNC "do-it-yourself" > Do I need a controller board with encoder input if my motors drivers have it already?
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  1. #1

    Do I need a controller board with encoder input if my motors drivers have it already?

    Hello, I have a general CNC/Encoder question...

    I'm developing a CNC Mill and I have closed loop stepper motors with drivers that have encoders input built in.

    Example Motor:
    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    I'm looking at potentially using Acorn CNC as my control board which seems to only have one encoder input for the spindle speed.

    Question is - do I need multiple encoder inputs on the main control board if my motor drivers already have encoder input?

    Would this just be redundant? Or is there some benefit to having additional encoder inputs on the main control board?

    Thanks for your time.

  2. #2
    Community Moderator Al_The_Man's Avatar
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Normally you only require one encoder per axis.
    It is to wherever the loop is closed back to.
    Systems such as Mach etc, do not close the loop back to the vector controller, but the independent drives.
    Sytems that close the loop back to the controller, do not need 'intelligent' drives, Galil Motion, Dynomotion etc. Just simple torque mode drives.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3

    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Gotcha - so in having 3 stepper motors for x, y, z - each with a closed loop between it and it's drive should be sufficient for error control. I suppose there's no need for additional error communication back to the main controller then.

    Perfect - this opens up a lot more options in terms of the controller board I can use.

    I was originally thinking Acorn CNC but will probably go with a Hicon Integra because I already have a license for Mach4. I like the fact there's tons of inputs & outputs for sensors and relays.

    I'll look at Galil and Dynomotion first to see if they have Mach4-compatible controllers and pros/cons over the Hicon.

    I'd welcome any input you have from experience.

    Thank you again!

  4. #4
    Community Moderator Al_The_Man's Avatar
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Dynomotion is a stand alone controller, but has the option of using the Mach as a HMI interface.
    There is a forum here for it.
    I have used Galil extensively, but it needs a 3rd party controller, at one time I programmed my own for the older cards.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  5. #5
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Hi,
    Dynamotion has no Mach4 plugin.

    Gallil does have a plugin but a three axis Galill controller starts about $2000.

    An Ethernet SmoothStepper is a Mach4 ready ste/direction controller and cost $180.

    Craig

  6. #6
    Community Moderator Al_The_Man's Avatar
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Quote Originally Posted by joeavaerage View Post
    Hi,
    Dynamotion has no Mach4 plugin.

    Craig
    Unless they have changed, they had a Mach3 HMI front end option, the trajectory control is done in the external controller.
    One advantage with Galil is the electronic gearing, up to 8 axis.!
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  7. #7

    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Nice - I see Dynomotion has a Mach3 plugin but I'm looking to use Mach4 for this build so unless I switch gears on that end...

    Galil's look like they'd be nice and you probably get what you pay for - but I'd need to add on the controller card and I'm building this into a mini-pc so I don't have a pci slot available for a full sized card without getting creative.

    I just searched the forum here and saw PMDX as an option as well. It could suit my needs and seems to be a little less expensive. I'm not sure which (hicon or pmdx) will be an easier install and has a good plugin for integration with Mach4 so a little research to do there.

    Hopefully can nail it down between the two before I start finding another capable controller.

    Thank you again!

  8. #8
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Hi,
    there are three cheap options for Mach4 ready controllers, all about $120, the UC100 (and not the Chinese fake), the PMDX-411 and the PoKeys 57CNCdb25.

    All are USB input to single port output. Given that they are single port you are very constrained for IO, inputs particularly. I would recommend a controller that
    has more IO, at least 'two ports worth'.

    The PMDX-424 has two port=34 IO's $250
    The UC400 has two ports=34 IO's $150
    The Ethernet SmoothStepper has three ports=51 IO's $180
    The UC300 has 5ports=85 IO's $150
    The 57CNC has 57 IO's. $150

    Of these the Ethernet SmoothStepper has the most complete suite of realtime supports, things like realtime (hardware) THC and laser rastering/vectoring.
    Note that the UC400, UC300, Ethernet SmoothStepper require one or more breakout boards, the 57CNC benefits from a breakout board and the PMDX-424
    has a built in breakout board.

    The cost of the breakout board/boards should be considered as part of the controller, in which case they all work out very similar in price, in the region $250-$350
    The Hicon Integra starts at $600 depending on required activations.

    Craig

  9. #9

    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    This is great information, thank you! I'm going to research all of these.

    IO is really important because I plan on having multiple limit sensors, e-stop, water cooling on/off control, and eventually a power draw bar.

    The Hicon now looks expensive compared to the other options. I'm going for quality and ease of setup (more so than price considerations - although budget is not unlimited, of course)

    The PMDX seems to have a lot of support for Mach4 and a good amount IO's - plus the option for a breakout board for spindle controls, etc. It was looking like a good choice...

    Now I'm going to take a look at these others you mentioned to see if there's any benefits over the PMDX. I have to research what these "realtime supports" are that you mentioned and if that provides a benefit for milling operations.

    Thank you!

  10. #10

    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Hmm...

    Without going into detail of why I'm eliminating the uc400, uc300 and 57CNC...

    The PMDX-424 and Ethernet SmoothStepper (ESS) appear to be the best options and both look like they have excellent documentation and support for Mach4.

    Ethernet SmoothStepper
    The ESS has an extra port on it which is a definite plus. I also like the Ethernet connectivity rather than USB - but that's a preference rather than one being better than the other.

    PMDX-424
    The PMDX board seems like it will be an easier install overall. Less breakout boards to deal with hooking up and mounting. Direct screw down connections right on the board.

    I did a little searching and found a bunch of threads comparing items from each manufacturer but they were all from at least 5 years ago...I'll continue searching.

    Any thoughts on which of these boards (ESS vs PMDX-424) is a better choice? Or is this simply preference at this point?
    - Not really concerned with the price on either - very acceptable
    - Does one have a better components? i.e. better/faster processor
    - Is one more reliable?
    - Is one inherently easier to set up?
    - joeavaerage, you mentioned the ESS has some realtime supports but I'm not sure I'll be taking advantage of them in a cnc mill scenario?

    Any input would be greatly appreciated.

    Thanks all!

  11. #11
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Hi
    both the ESS and the PMDX-424 are excellent choices, you would not be dissapointed with either.
    Both are well made and both have excellent manufacturer support, nothing to pick and choose between
    them.

    All external motion controllers provide realtime supports.

    Lets take a fairly simple example, say a home switch.

    If you rely on home switch event to propogate back to the PC and Mach the communication delay could be tens of milliseconds, which is
    unacceptable. So the external motion controller monitors the home switch input and stops motion imediately when an activation happens.
    It then reports to Mach, but the initial and time critical bahaviour, namely stopping the axis happens under direct hardware control automatically.
    That would be an example of a realtime support.

    All motion controllers are required to offer realtime supports, things like home switches per my example, but limit switches, probe events.
    Some are related to a specific operations, single point lathe threading for example. The motion controller has sole responsibility for the tool
    to engage the workpiece at a precise time so that successive passes of a threading tool are synchronized, and one pass does not obliterate
    earlier passes.

    The ESS has a full suite of reatime supports including single point lathe threading, backlash comp, realtime (hardware) THC, laser rastering.
    The PMDX-424 has single point lathe threading but does not have backlash comp,THC or realtime laser ops. Unless you have specific need
    for a particular support then you won't miss it. If however, for example, you decide to extend your machine to be a plasma table then you will
    probably need realtime THC and therefore the ESS would be the best choice.

    Craig

  12. #12

    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Beautiful. That explains things perfectly.

    As I researched the ESS more, I found the plethora of BOB's available and things started making much more sense as well.

    I don't believe I'll have an initial need for some of the realtime supports of the ESS but I may for future projects so I feel like getting accustomed to the ESS will be the best bet.

    So now as I thought I had things settled - I'm now on to researching BOB's for the ESS.

    Thank you both again!

  13. #13
    Community Moderator ger21's Avatar
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Look at the MB3 first, and you won't need to look any further. cncroom.com
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  14. #14

    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Ha! I came back to post my decision and it was - immediately the MB3 ...and here I'm reading your suggestion of just that.

    Thanks

  15. #15
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Hi,
    ger21 is right, the MB3 is a well thought out board and very nicely made. If it can be said to have a limitation is the you have to use the
    resources and achitecture that the manufacturer has determined, which might be considered a loss of flexibility. Having said that
    the reports from users is very good indeed.

    When I was building my machine the MB3 had not been released and so I used very much simpler one-port bi-directional boards. Because
    electronics is my thing the little bits of extra circuitry to do different things is no trouble. Depending on your electronic skills that may not
    be the case for you. On the other hand I have retained all the flexibility that comes form such simple boards.

    Craig

  16. #16

    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Hey - not sure why but maybe you all might know something I don't?

    cncroom.com is selling the ESS for $276 where as Warp9 is selling it for $180.

    CNCroom: ]ESS [ESSV1] - $276.92 : CNCRoom, The Room for CNC'ers, from Mini to Big machine, from Hobbyists to Gurus
    Warp9: https://warp9td.com/index.php/products

    I was going to just buy it all from cncroom.com but obviously not for $100 extra. Is there any reason for this price difference? It's the same thing, right?

  17. #17
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Hi,
    the last time I checked the price for the ESS/MB3 combo from CNCRoom had the ESS at the same price as from Warp9TD at $180USD.

    Could the website have added shipping automatically or converted to your local currency?

    Craig

  18. #18
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    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Hi,
    just revisited the CNCRoom site and I come to the same conclusion as you, they seem to be charging a premium for the ESS
    part of the combo. That is a recent development, as of a week ago the ESS was srill $180.

    Craig

  19. #19

    Re: Do I need a controller board with encoder input if my motors drivers have it alre

    Thanks for the feedback. Maybe a recent typo on their part. Placing the two orders separately then... thanks again for all your help!

    Dan

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