Chinese CNC 3020 / 6040 - USB variant

Yep Rod, I really think you nailed it in your first 4 lines.

Very well said.

I was quite unaware Banana Benders could be so eloquent

Guys you are missing the basic concept. With linuxcnc transmitted over lan to a mesa card. That instruction could be parsed and sent out over many different transmission protocols as basic gcode instruction which grbl is capable of using.
the real time bit is a fallacy. ok grbl only handles 30k speeds, smoothie 250k (still accepts grbl styled instruction) so if the hardware is handling the operation it is no different that an instruction sent to a mesa card all be it slower for design reasons. windows based hobby machinists are not looking to become experts in linux or have a PC sat on a desk only used for one thing. My current machine handles cad, cam, simulation and the machine GUI. Apart from Fusion 360 how many other cad packages are written for linux. The discussion has gone from how can USB be achieved to excuses and outright denial that its even possible. That little serial message sent to a mesa card can be output via a usb port. speed is an issue but that can also be manipulated, Im sure the original spec for a parallel ports data rate is far less than that of even USB1.
many linux and indeed mach3 setups are using old parallel ports and bit banging the drive pulses. if the instruction was output as a gcode instruction to the usb instead of been bit manipulated to pulse the parallel port pins then that is what we are asking.

The advantage linuxcnc has as a gui over current grbl control panels is the canned cycles and probing (an extended gcode commeand set). Grbl will never handle these commands that is correct but if those command were written and transmitted as move instructions and the math was handled inside the gui then it is most definately possible - guess what linuxcnc does exactly that before bitbanging the pulses out of a parallel port. I may not be a programmer but when it comes to phsyical hardware and interfacing communications i do know a thing or two.
I have worked on forign vessels with a whole array of survey gear and had to get it all to talk to each other and a good old windows pc, worked with Industrial and fibre networks and automated my fair share of factory plant using control softwre such as Iconics not to mention PLCs. I get the distinct impression programmers can only do whats safe and what they know. No matter where this thread goes the answer will always be NO, Im not going to continue with this thread as its not ever going to be productive. Windows has won.

MrJTJinx wrote: Guys you are missing the basic concept. With linuxcnc transmitted over lan to a mesa card. That instruction could be parsed and sent out over many different transmission protocols as basic gcode instruction

Thats not how it works. You are still in the wrong paradigm.

Linuxcnc does not send gcode to the Mesa becasue Linuxcnc is the motion controller. That means it consumes the gcode.

What happens is that Linuxcnc tells the MESA stepgens to oscillate at a given frequency. Thats what the Mesa card does happilly forever until it is told to stop or vary the frequency. Linuxcnc can tell it to vary that frequency 1000 times a second.

Linuxcnc has already parsed the Gcode Well before hand and converted it into instructions to the Trajectory planner that are buffered. So by the time Linuxcnc starts telling the stepgens to generate steps, the gcode has essentially been thrown away as its done its job.

So when people say you could write a USB3 driver, it has to be capable of sending that set of low level instructions in real time.

Guys you are missing the basic concept. With linuxcnc transmitted over lan to a mesa card. That instruction could be parsed and sent out over many different transmission protocols as basic gcode instruction which grbl is capable of using.

Respectfully I believe you are missing our point. Linuxcnc will _never_ output gcode to an external controller.
If it did, it wouldn't be linuxcnc any more - that is the principle difference of linuxcnc - linuxcnc _is_ the controller.

Chris M

MrJTJinx wrote: No matter where this thread goes the answer will always be NO, Im not going to continue with this thread as its not ever going to be productive.

The reason why the answer is always NO is that you are always in the wrong paradigm. There is no point getting one motion controller control another motion controller. It particularly makes no sense when you are wanting to control a feeble controller such as GRBL with one that has vastly more capability and processing power that is orders of magnitude greater than the little Arduino.

It is this massive processing power on the OS platform that allows Linuxcnc to do all those things you yearn for that Grbl does not have the grunt to do.