Chinese CNC 3020 / 6040 - USB variant

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06 Apr 2018 06:28 #108482 by Maitland
I had a hardware unit which may have had bugs, and I used it with some software which may have had bugs. It failed wrong- side. Therefore any hardware used with any software is dangerous. I think there could be a flaw in this argument somewhere.

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14 Jan 2020 08:30 #154806 by MrJTJinx
What is the future of Linuxcnc if it is never planned to support USB.
A PC with an installed Parallel port would now be in excess of 15 to 20 years old and built on pre Pentium architecture. The idea of running a machine on a PC built from a scrap yard makes no sense.
Ok there is limitations but suerly a git fork could be created for a USB version even if it was limited in functionality.
GRBL works ?

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14 Jan 2020 10:42 #154810 by rodw
Linuxcnc cannot support USB becasue USB is not real time.
The Mesa ethernet cards are really worth looking at or use their PCI/PCIe cards attached to a daughter card but there are several other options.

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14 Jan 2020 12:14 #154819 by Maitland
"The Mesa ethernet cards are really worth looking at"

Ethernet isn't real time either. If LinuxCNC can work with ethernet latency, it can work with USB, or serial or Bluetooth for that matter. PCI is practically dead: PCIe cards are expensive ($209 plus breakouts for Mesa).
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14 Jan 2020 13:27 - 14 Jan 2020 13:33 #154820 by MrJTJinx
Its starting to get expensive having CNC as a hobby.
£4500 is not un common as a build price for a completed CNC project which is starting to get into the realms of a second hand Haas.
The Mesa board at least looks affordable.

Is it possible to use a Lantroxix lan printer server or similar device which provides a lan to Lpt interface?
Last edit: 14 Jan 2020 13:33 by MrJTJinx.

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14 Jan 2020 13:42 #154823 by Todd Zuercher

What is the future of Linuxcnc if it is never planned to support USB.
A PC with an installed Parallel port would now be in excess of 15 to 20 years old and built on pre Pentium architecture. The idea of running a machine on a PC built from a scrap yard makes no sense.
Ok there is limitations but suerly a git fork could be created for a USB version even if it was limited in functionality.
GRBL works ?


Why are you hating on the parallel port so much. It is an excellent, simple and inexpensive way for a pc to have direct access to miscellaneous digital i/o. And current new(ish) chip-sets are still available and easily found that still have and come with them installed. Such as this www.asrock.com/mb/Intel/J4105B-ITX/index.us.asp

Sure using a parallel port may not be the best or most elegant way to connect to and control a CNC machine. But it is one of the simplest, most cost effective ones and is ideally suited for basic simple entry level machines like a simple 3 axis router table. Easily fulfilling the needs of 80% or more of entry level machines.

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14 Jan 2020 14:55 #154826 by MrJTJinx
Im not beating down on the parallel port as much as i am the retentive nature of programmer to not expand beyond their imagination. The question is why not create a USB variant why only stick to the parallel port.
Im looking for a GUI which will afford me the ability to do tool length, probing and possibly canned cycles. These are all functions which can be managed by the application (as Linuxcnc does). There are thousands og GRBL users out there who are crying out for a better GUI. Lets face it we all want Pathpilot. Even it is more user friendly than the dedicated controls used by industrial manufacturers such as Haas. The users of GRBL are well aware of its limitations ie lack of spindle sync so if its the same limitations with a USB version of Linuxcnc, so what. At least it would improve the GUI and give GRBL users some more toys.
As it happens AsRock have not been very reliable machines just for reference.
How dificult would it be for a genius programmer to write a HID into linuxcnc.

As the parallel port disapears then there is a much greater requirement for data aquisition cards to fill there place, these cards are inherently expensive making a self build cnc machine that much more expensive. Once a self project starts to exceed £4500 we may as well buy a second hand cn machine like a Haas VF1 for just a couple of thousand more.

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14 Jan 2020 15:52 #154828 by Todd Zuercher
Because to use a USB interface would essentially turn Linuxcnc into Mach3. (or at least add most of Mach3's biggest problem points to it.)

If you want a better UI for GRBL then write one. Linuxcnc is not GRBL and under the skin LinuxCNC works very differently.

One of the basic rules Linuxcnc is built on is closed loop feedback. In order for Linuxcnc to even run an open loop stepper system, it has to be "fooled" with an internal feedback loop. This is why good real time is so important and having good real time is what makes things like probing and spindle synchronization work so well in Linuxcnc.

The imminent demise of the parallel port has been professed for more than 30 years. Sure it is dead as far as printers are concerned, and has been for a long time. But it is no closer to going away completely now than it was 15yrs ago. I'm getting tired of hearing about it.
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14 Jan 2020 17:07 #154832 by MrJTJinx
Todd, your being hostile.
so basically programmers like you just want to do your own thing without even trying to accept or understand the requests of others.
I made a clear and concise argument so to converse with you further would be a waste of oxygen.

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14 Jan 2020 17:35 #154835 by tommylight
Linuxcnc is a machine controller with all the bells and whistles that go with it, so real time is real requirement.
USB can not do real time, not by a long shot, it is inherently impossible to do control a machine through it.
There are solutions around it, like mach3 and some controller boards for it, but still it is not real time as stopping the machine while working or messing something up will last long enough for the machine to do it's thing, leaving the user with tears while watching the messed up machine.
On the brighter side of things, if you insist on using Linuxcnc through USB, search for DaBit, he did make it work to a certain extent quite well.
And i agree with Todd, parallel port is not going away any time soon, it is direct access hardware and that makes it very usable fur such needs, and it is very cheap.
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