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Author Topic: External Motion Controllers.  (Read 278 times)

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External Motion Controllers.
« on: May 14, 2020, 03:53:41 PM »
Good day to everyone,
My name is John (Gargle) a semi retired 72yr old mechanical engineer. I have a small CNC router similar to an X Carve that I constructed from a kit . I run it via GRBL 0.8 and also through Easel (Inventables).  Would either of these be considered to be a suitable external motion controller to utilize Mach 4 Hobby? If not, any suggestions as to what I should use would be greatly appreciated. Also, advice on a suitable Mach 4 plugin device. 
Easel works well but lacks full 3d ability in its current form.

I have designed a much larger machine, currently still on the drawing board, so it is important to me to select the right devices that will ultimately run this machine correctly with Mach 4 as well.

Best Regards,

« Last Edit: May 14, 2020, 04:06:39 PM by Gargle »
Re: External Motion Controllers.
« Reply #1 on: May 14, 2020, 05:08:38 PM »

GRBL hardware is not applicable to Mach4.

An external motion controller, any external motion controller, requires a plugin that adapts the hardware to Mach4.
For instance the Mach4 trajectory planner produces numeric P(osition) V(elocity) over T(ime) data. The plugin digests that
data and translates that data to the hardware signals required for the controller to produce the pulse streams which in turn
control the axis motors.

The software plugin is therefore an absolutely critical and technically demanding piece of software and as such represents a huge
investment on the behalf of the hardware manufacturer. Note also that the plugin is applicable to that hardware controller alone,
as every controller differs thus an ESS plugin will be of no value to your GRBL hardware.

In order to craft a plugin requires an in depth knowledge of the internal workings of Mach4. As such anyone wanting to produce
a plugin for any piece of hardware, be it a motion controller or a pendant or bespoke communication unit, is advised to sign
a N(on) D(isclosure) A(greement) with NFS to get the required inside knowledge. Note that NFS are generally delighted that
someone should want to build a plugin, after all it benefits the uptake of Mach4 and thereby NFS's bottom line. Having said that
neither are they interested in distributing proprietary information about their product (Mach4) to all and sundry, serious players
need only apply.

At the current time there are six (seven if you include XHC, a dodgy Chinese made controller supposedly Mach4 capable) manufacturers
of external motion controllers that have an operable Mach4 plugin. Four of them are considered 'value end of the market'......with various
models of controllers ranging from $120 to $250, with various features and capabilities. They are:
1) Warp9 TD, the Ethernet SmoothStepper (ESS) is the model of choice
2)PMDX, the PMDX-411 and PMDX-424 are the models of choice
3)CNCDrive, the UC300, UC400 and UC100 are the models of choice
4)PoKeys, the 57CNC and 57CNCdb25 are the models of choice

I personally use the ESS, it has arguably the best suite of realtime supports of any Mach4 external motion controller on the market at the current time.

As an example of the investment you might consider if you wanted to switch to Mach4Hobby:

Mach4Hobbly license                   $200
ESS                                           $180
MB3 breakout board                    $180

Note that I allowed an MB3 breakout board, perhaps the most expensive board matched to the ESS but arguably the best developed
and high quality board.

Of the different boards from different manufacturers, some of which require a breakout board and some that do not, the prices will vary form
perhaps as low as $320 up to about $460. Either way you need to consider these figures.

If my understanding is correct GRBL hardware has stepper drivers included? None of the motion controller/breakout board hardware I've
mentioned have any stepper drivers, they are separate units.

May I suggest downloading Mach4Hobby and experimenting with it. If you don't install a motion control plugin, but rather just stick
with the Sim(ulator) plugin (supplied) you can use Mach4 in Demo mode as long as you like. If you install a motion control plugin, Mach4
considers that you now have the ability to control hardware and that in Demo mode you have a time restricted use. For instance if you buy
an ESS and install the ESS plugin you can now control your machine but for a maximum of six minutes before you will be required to
re-start Mach4, at least until such times as you license Mach4.


« Last Edit: May 15, 2020, 04:57:37 AM by Tweakie.CNC »
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