What's the skibby on motion controllers?

[hoga01]

Will someone please enlighten be on motion controllers. Generally, I understand what they're for and how they work but I'm confused about their implementation. What language is used for programming them? Do they operate in conjunction with a host computer? If so, is the communication between the host computer and the motion controller a standard language or proprietary? Please help, I'm lost on this. My exposure to date is only simple step/direction control.

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[vacpress]

Hoga,

That is a great question, which I cannot answer. I look at things like the G100 from Gecko, or all these 'gaelil' or IMS 'motion controllers' on ebay, and really wonder what benefit they may have for us..

What I do understand is that many of them use RS232 to communicate using some command interface. I think some have modes for sending a pretty basic coordinate, and it goes there, and others are far more involved. To use one in a CNC machine, in most cases I think you have to write a program that can take GCODE or similar script, and convert it into commands for the specific device you are using..

For example, your gcode parser on the PC could read the gcode, conver the move commands or whatever and then send them via a custom VB or similar program, and send the device off on it's way. I think very powerfull systems can be created this way, and I bet many devices have libraries and examples pointing this way.


However, all of that is conjecture from reading about PLCs and other machine control systems on manufacturer websites..

To really get it figured, find some stuff on ebay, find the manufacturer, look for the manuals, even if you cannot afford the device, read the specs..

Then you will know more than me.

[vacpress]

A bit more conjecture.

I believe you could use a PLC or even a higher end basic stamp or other 'easy' device(or just a PC), to store and send commands, some motion controllers even have a PLC of sorts built in, from what I gather reading EBAY posts.

I have seen the inside of a commercial gantry router. It had 3 largish chinese looking stepper drivers, a seperate VFD for the spindle speed and a panel mount that communicated with that. Then a circuit board with a microcontroller and a bunch of memory and several RS232 or I2C or similar outputs leading to the host computer and the spindle controller VFD.

From operating it I know the PC program displayed and sent the GCODE(or modified gcodeish script) to the circuit board in the machine(motion controller) all at once, then that board sent step\direction signals and communicated with the spindle.

This is what motion controllers do, in effect. Getting them to obey is another issue. Some must be like PLCs and use semi-proprietary languages, others mut be sort of dumb and only understand 'goto' type commmands that they interpret.

I want to have a 'for the really busy, if not quite 'dummies'' version of what the Gecko motion controller offers. Because it was developed with artsoft, I hope it does alot for Mach3 owners.. But I simply cannot tell from the blurb on the gecko-soft website.

Hope I have helped despite my real lack of knowledge.

[Al_The_Man]

Will someone please enlighten be on motion controllers.

As Vacpress pointed out it is a very broad question, but basically Motion controllers can be identified as being in three groups, or maybe four if you count PLC's.
The first three would cover motion control where interpolated moves of two or more axis are required.
One such type uses a Dedicated motion card that sits in a PC slot such as Galil & Delta Tau etc.
These close the motion loop inside the card with motor command and feedback is constantly monitored, these use their own native language that can be programmed this way, or will need an interpreter and HMI for G code type programming, the PC just acts as a HMI.
The second would cover the stand-alone motion controller which often can be communicated with a PC or Operator terminal serially and a program would be written in Native language and the program downloaded to the unit and run in a dedicated application, limited operator programming neccessary.
An extension of this system would be dedicated commercial systems like Mitsubishi and Fanuc etc.
These posses embeded software with their own HMI and G code programming ability etc. and/or conversational programming.
The Third is the type popular here, where the PC act as a HMI and controller through the parallel port, but the motion control loop is not closed within the controller, as is the case with the preceeding types.
IOW commands are given via step/dir signals to semi-intelligent drives, but the controller does not have feedback as to the status of the motion.
The PLC type is capable of Motion control, but because of the slow update time is not used for interpolated moves, only point-to-point.
There are also systems that us High speed bus systems like ModBus etc to control intelligent drives, these can often be considered closed loop. or semi-closed loop.
This is just a brief touch on what is out there, you can search for more info on each system to get a better idea.
*HMI Human-Machine Interface.
Al.

[hoga01]

Thanks to everyone for responding, I appreciate the help. After reading the replies, it struck me as funny that the answer to my broad and absurdly complicated question is simply "yes".
Thanks again.

[vacpress]

hoga.

actually, the answer was 'no', essentially. to use a dedicated motion controller to work your low-budget hobby machine would most likely require signifigant specialized hardware and software devlopment. forget mach. you will end up with a simple RS232 communication app on the PC that sends the gcode, raw, or formated to a memory in the motion device, or attached to it.

that is the easy part. the hard part is converting standard gcode into something the controller can understand, and also handling all the other factors involved. lots of code! lots of specialized non-standard stuff to learn for a 1-off.. good experience, a great project, but probably not for a casual 'cnc hobbiest'.

i certainly wouldnt try it unless there was signifigant information about the device and my specific applications.. However! As I noted, it is possible some popular motion devices have some or most of this work done for you.

It sure would be sweet to kill the PC in favor of a dedicated embedded solution and closed loop control! no more 'lost steps', no more PC crashes durring machining. no more ~$1000 machine totally dedicated to running the cnc.

Please let us know if you get anywhere with that!

[hoga01]

Well, once again, I thank everyone for their input.
For the record, I don't have a motion controller nor the immediate need for one: I was only after knowledge and the answer panned out exactly as anticipated. Maybe there will be some actual standards in the future; I hear Allen Bradley is working on it. In the meantime, I guess everyone is stuck buying equipment based on compatibility instead of merit? I hope nobody's offended but it's all just plain stupid.

[Al_The_Man]

I hear Allen Bradley is working on it.

Allen_Bradley set a standard!! That'l be a switch, for CNC at least
As far as buying based on compatibility, I would say it is more like cost.
Merit usually cost's , and like alot of things in life, you get what you pay for.
Many of the members of these forums are Hobbyist's, and to get into playing with CNC, cost is often a concern.
I am fortunate enough to have had the opportunity to experience and implement quite a few of the more 'sophisticated' systems, to some degree this spoils one.
In spite of the many different competing systems, generally at least they all have in common is the RS274 programming language using the cartesian co-ordinate system.
Which I think, answers one of your original questions.
Al.

[vacpress]

http://cgi.ebay.com/Syn-Tek-PCI-M114...QQcmdZViewItem

here. check that guy out. follow the links.. looks neat! too bad it would probably take alot of work to get it to listen to gcode!

[Al_The_Man]

[url]
here. check that guy out. follow the links.. looks neat! too bad it would probably take alot of work to get it to listen to gcode!

Looks interesting, I went to the web site, but there is no mention of native programming language or minimum communication software etc?
Al.

[vacpress]

Hmm. There is a link at the bottom of the first page.. 'next'

it took me to a page about software. i didnt look at it too hard.. i need stepper driver boards still...

figured that would give people an idea... it looks to me like it operates via a serial link of some sort.. no memory on it?

i thought the list of interpolation modes and other information might be interesting to the original poster of this forum...

al, do you know of any motion controller products aimed at cnc? i mean, besides the hobbiest stuff, like the deskCNC usb board... that is also a motion controller... should point that out...

seems like there must be a few motion controllers that are popular choices for commercial gantry routers, and as a result have alot or all of the code figured out for us...

i am thinking of the control panel in the axyz corp router ive seen inside.. it looked very easy to integrate.. it has step\direction outputs, a vfd output of some sort, and limit switch inputs... it also had a control panel that let you step through gcode lines on an lcd, enter individual commands, etc... it could store upto 16 jobs, within a 500k memory or something tiny which meant it almost always needed a drip feed of code...

-R

[Al_The_Man]

al, do you know of any motion controller products aimed at cnc? i mean, besides the hobbiest stuff, like the deskCNC usb board... that is also a motion controller... should point that out...

seems like there must be a few motion controllers that are popular choices for commercial gantry routers, and as a result have alot or all of the code figured out for us...

There is Delta-Tau CNC, Galil with Camsoft, Acroloop with MotionMax.
There were a few very cost effective systems with all the above motion cards, that were developed under DOS with the ISA buss, unfortunately, with the advent of the PCI etc, they fell by the wayside, which was very unfortunate, as they possesed all the features you really need for multi-axis true closed loop control.
For example Messer MG Systems and Koike-Arunson used the Acroloop on their plasma tables, they also had a AcroMill s/w which I did some knee mills with, even has custom template shape programming.
If anyone gets hold of any of the ISA Acroloop cards, I have the old DOS software and manuals.
I am also interested in what Mach is doing with the Galil card system, which should result in a truly closed loop system analogue or digital control.
Al.

[unterhaus]

Is Art really looking at the Galil? Seems like a lot of work for a very small market.

Ignoring the GRex for now, if you want closed loop with a pc, EMC is still the only game in town for free software. I'm getting a Mesa Electronics PCI Anything card tomorrow http://www.mesanet.com/ -- it will do closed loop analog servo with encoder feedback. There are a number of other hardware choices with EMC. However, if a card has intelligence on board (such as Galil) it doesn't work with EMC at this point. The loop has to close in the computer to fit the current EMC model.

[vacpress]

Cool.

So, this Grex.. I thought it was the 'g100' or something along those lines, however, what is it?

I had thought it was developed with mach in mind?

[Alex_Fox]

Hello, hoga01

Motion controllers require a load (something to be moved), a prime mover (something to cause the load to move), some sensors (to be able to sense the motion and monitor the prime mover), and a controller to provide the intelligence to cause the prime mover to move the load as desired. Just about everything that is man-made requires motion control during its manufacture, packaging, distribution or use - that is what Wikipedia says about their implementation.
As for the language they use, smart drives and stand-alone motion controllers often use proprietary languages, as this article claims. I work for mobile app developers london but cannot really understand how it all works too.
Try reading these guides, probably, they will help.
Hope