Newb question: Converting G-code to 1-10 VDC analog signal?

Folks,

I am trying to repurpose a meter by meter XY platform into a 3d printer. The existing system uses linear motors driven by servo amps that get a 1-10 VDC control signal. I have seen a Rambo (?) controller board used on the larger delta printer that appears to control stepper amplifiers. Can it also control servo amps?

I do understand that I am building a system upside down with the XY sitting on the bottom and at high speeds the taller objects will sway like a tree. I am working with what I have.

The existing motion controller is an older two axis delta tau system that is controlled via some proprietary serial commands from a older HMI controller.

Any help is appreciated.

Thanks

Larry

Use LinuxCNC.

- You might be able to modify the coding to apply an analog signal using the RAMPS 1.4 software and some Arduino hardware. If you have a nice platform I would suggest investing in some PWM Steppers and just buy a RAMPS 1.4 kit from eBay, the kits are usually under $30.

GOC, the existing platform can support approximately 1000 pounds, the linear motors and amps are functional, I've got positional resolution to at least .001 inch possibly finer. It does not make sense for me to rebuild the table with steppers and linear rails.

After posting last night, it occurred to me that the serial line between the 486 HMI and the delta tau controller is probably ASCII. I am in the process of coming up with a serial tap that will let me see what commands are being set. If I am extremely lucky, that serial communications is already G-Code. If it is not G-Code but still ASCII text, I guess it will be time to find some sort "magic" to convert G-Code to whatever language the controller speaks.

Why not buy a controller off the shelf for a $100 (aproximately) that will allow you to use STL files with out the hassle that you are currently enduring?

- Out of curiosity. If you do manage to find out how to communicate with your existing motor controllers via serial, how do you plan on keeping that in sync with your Z-Axis & Hot-End Stepper? Do you plan to code some custom controller software for this application?

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Originally Posted by -willy-

Why not buy a controller off the shelf for a $100 (aproximately) that will allow you to use STL files with out the hassle that you are currently enduring?

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I am not familiar with the controllers you are talking about. Any suggestions?

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Originally Posted by GOC

- Out of curiosity. If you do manage to find out how to communicate with your existing motor controllers via serial, how do you plan on keeping that in sync with your Z-Axis & Hot-End Stepper? Do you plan to code some custom controller software for this application?

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I am ASSUMING (with all that entails) that if I find some magic to convert the G-Code to something suitable, the Z axis will still be controlled with the standard G-Code. Print a plane, index Z, print a plane, index Z, repeat. Since most of the motion is in the XY plane, the biggest delay is happening right after the Z axis move. If I perform some sort of First In First Out logic magic, the XY commands will be waiting when the Z is done moving.

I have not worked with G-Code before, so it very possible I am just blowing smoke. I will find out soon enough.

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Originally Posted by LarryC

I am ASSUMING (with all that entails) that if I find some magic to convert the G-Code to something suitable, the Z axis will still be controlled with the standard G-Code. Print a plane, index Z, print a plane, index Z, repeat. Since most of the motion is in the XY plane, the biggest delay is happening right after the Z axis move. If I perform some sort of First In First Out logic magic, the XY commands will be waiting when the Z is done moving.

I have not worked with G-Code before, so it very possible I am just blowing smoke. I will find out soon enough.

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That is exactly what LinuxCNC does for you plus it controls the servos directly from the parallel port or IO on whatever embedded system you choose to use. Not a Raspi, the Raspi cannot run a real time Linux kernel sufficiently well.

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Originally Posted by Mjolinor

That is exactly what LinuxCNC does for you plus it controls the servos directly from the parallel port or IO on whatever embedded system you choose to use. Not a Raspi, the Raspi cannot run a real time Linux kernel sufficiently well.

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Thank you. It looks like I have some more investigation to do.

LarryC

- I'm curious to see the hardware your working with so that I may get a better understanding. Would you be able to snap/upload a few pics of your table, controllers, & motors (including inputs & wiring leading out of the devices)?

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Originally Posted by LarryC

I am not familiar with the controllers you are talking about. Any suggestions?

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There are several possiblities. A easiest one that comes to mind is something that has been made for a printer that will use any gcode generator (Slic3r, Repetier-Host, Cura and so on).
This company (PrintRbot) offers their current revision at $100. http://printrbot.com/shop/printrboard-rev-f/
http://3k8g8c3p564l1zjnb621d3aoii6.w...vF-510x510.png

That board is for stepper motors, not servos.

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Originally Posted by Mjolinor

That board is for stepper motors, not servos.

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This would explain why I did not understand.

Mjolinor;

I looked up LinuxCNC and, as one would expect, it's not possible to run it on a Windows machine. From the LinuxCNC wiki (scroll to bottom):

"Why won't LinuxCNC run on Windows?

1. LinuxCNC runs in real-time, to give smooth motion. This is critical to accuracy and machine life. Hard real-time is not available on Windows in a price range many can afford... especially those interested in using a PC-based control.
   
2. LinuxCNC is intended to control machine tools. Machine tools are DANGEROUS and reliability/consistent behavior is extremely important. Compared to Windows, few viruses affect Linux. Even without consideration of viruses, Linux is far more stable.
   
3. The above also apply to virtual machines (e.g., VMware or Virtual Box) and emulators. It may be possible to trick LinuxCNC to run on a virtual machine but do so at your own risk!
   
4. The above notwithstanding, one can access a running LinuxCNC machine from a Windows machine, e.g., by running a Windows-based VNC client or X11 server."
   

This states that a dedicated Linux system is necessary. The Windows preferred alternative seems to be Mach3, but it's not free at $175. Do you advocate buying a dedicated system, devoted to Linux, over running Mach3 on a Windows machine, given that the costs are probably about equal? This question assumes, of course, that one doesn't already have a dedicated machine running Linux, as i expect most don't.

I suppose there is the alternative of partitioning a section of the hard drive to running Linux. What would you suggest?

No point asking me what I suggest. I don't use anything by Micro$hite other than mice. :)

My Stratasys printer sits idle because it uses Windose and I don't.

Mach 3 is not really a Windows equivalent as it will not directly control things to the same extent. For your purposes either will do as you already have the rather expensive hardware that Mach3 requires.

You do not need to buy Mach3, the trial version will do everything you need, it is just limited in the lines of code it allows but it allows sufficient to prove viability before you spend anything.

I would go with another partition for Linux because if you meet a problem then you can get it fixed, the LinuxCNC community is very strong active and capable or do both, one should learn something new every day and if you do both you will be learning ten new things every day for 5 years. :)

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Originally Posted by Mjolinor

My Stratasys printer sits idle because it uses Windose and I don't.

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So... how much are you selling it for? Because it would just be a shame for it to sit idle forever.

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Originally Posted by Feign

So... how much are you selling it for? Because it would just be a shame for it to sit idle forever.

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It's in the UK and you're not. :)

I just spent 6 months dissecting the CMB files so that I can now use any gcode with conversion then send it to the printer.

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Originally Posted by truly_bent

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I suppose there is the alternative of partitioning a section of the hard drive to running Linux. What would you suggest?

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- I would set up a partition for Linux and dual boot (Windows & Linux). Alternatively you could also set up a virtual machine to run Linux as well.

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Originally Posted by GOC

- I would set up a partition for Linux and dual boot (Windows & Linux). Alternatively you could also set up a virtual machine to run Linux as well.

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A virtual machine will not work, the timing cannot be controlled by the real time kernel if it has Windo$e behind it.

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Originally Posted by Mjolinor

A virtual machine will not work, the timing cannot be controlled by the real time kernel if it has Windo$e behind it.

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True, the RT Kernel will be fighting windows for CPU Priority. As a revision to my prior remark I can only suggest running a Linux core and use Virtual Box to run the Windows OS.

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Originally Posted by GOC

True, the RT Kernel will be fighting windows for CPU Priority. As a revision to my prior remark I can only suggest running a Linux core and use Virtual Box to run the Windows OS.

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Or just dump Micro$hite and use a proper OS all the time. :)