Can't access COM PORT for GRBL Controller !!!

Hello,

I’m doing a simple 2-axes plotter. I’m using Arduino UNO with the GRBL shield and 2 A4988 drivers. I connected everything and uploaded the grbl software from Github and I can move the two stepper motors from the serial monitor inside the Arduino IDE, as well as, navigating through the grbl setting and controls.

the problem comes when I’m trying to connect my setup to an external software other-than the Arduino IDE!! I keep receiving messages with the meaning that the software can’t find the port or can’t access it!! I got this problem with grbl controller, universal gcode sender and chillipepper.

Any help help will be highly appreciated.

Thanks in advance.


2018-12-15_23-56-21.jpg

I have faced problems like that when I try to run one Arduino window and then an other program system, Estlcam. That is because the PC allocates/connects the COM port to the first ot those systems. Then that port is locked and the second system can not open that COM port. I do like this: Pull out the USB connector, and put it back when You hear the signal from the PC noticing that the USB port was disconnected. Then open the system You want to run.

The suggestion by Railroader is perfectly acceptable.

In my case I simply close the program that is currently using the COM port.
Or if I want to swap between GRBL programs I simply use the disconnect option that most GRBL programs provide and re-connect with the next one.

You neglected to say what OS you were using but I use Windows (various flavours) with no problems.

Don't forget to set your firmware settings too in GRBL for the steps etc.
Most GRBL programs will connect at 115200 baud so also make sure you have the correct baud rates set.

@ballscrewbob
My knowledge and experience of Arduino IDE started growing not so very long ago… Is there any way to disconnect sn IDE Window? Selecting an other USB port ought to work as a switch off. Then I need a hub and some dummy Arduinos...

As you say you can swap the com port in the IDE too.
That will work also.

But unless you have multiple boards you wont be able to use the IDE at the same time as your GRBL based board anyway except with other boards. However as you say and more so if it is a windows computer you should be able to select any other port from the IDE to disconnect the one you want to free up for GRBL.

Have 3 GRBL based machines here and another 15 live boards and no real issues.
I can run three GRBL programs at once and still use the IDE on my other boards.

Thanks a lot! I have not got GRBL running yet but uses Estlcam for positioning my desktop CNC, cut simple straight lines, while making UNO sketches controlling the more sophisticated CNC work.

I dont mind esticam but I prefer UGS (Universal G Code Sender) but use LASER GRBL for all my laser work.

I cannot see the sense in all the extra coding to do it from a sketch especially with the memory constraints.

So many FREE programs out there that will accept a multitude of formats and spit out the G-CODE for you.
For 2D with no z axis laser grbl is great. It also now accepts vector drawings too.

I downloaded a free Fusion 360 but gave up rather soon. Got another CAD program that I haven't given much time. I make fntions like cut holës, cut Squares, inside or outside the coordinates using them äs a private lib does most of the "routine jobbs".
2D CAD sounds very interesting. Can You provide me a link to that?

If your holes are not quite right double check the GRBL firmware as there are a couple of places you can tweak to help with that aspect. Junction deviation and Arc tolerance are the two to watch for. Mine are at .01 and.002 mm respectively. I could tune them more but they do everything I need.

Most programs also have an option somewhere to also help with curves and radius.

Laser GRBL is not true CAD in that it can take pictures / vectors / G-code in and do some very fine work. Nice option is also to save the picture as a G-code file too which is great for repeat ability and such if you have a few things to do.

FlatCAM is another pretty decent free package. Used it a few times for smaller stuff.

I simply could not get to grips with fusion either LOL

Thanks a lot again!
I'll check those links!
How do You handle backlash in Your equipment?

Anti backlash nuts.

A lot depends on what you are using for the leadscrew ?
Its it isn't a proper leadscrew then a similar arrangement to a proper spring loaded anti backlash nut is also quite easy to fabricate.

It still needs to move fairly easily but with a very slight amount of pressure so as not to make the servos work too hard.

If you have a DTI you can easily measure the backlash and IIRC mine is in the region of .001 mm which is probably too fine for laser work but one of my home brew machines also has an interchangeable sled to be able to use a spindle so its one of those things I am not going to touch.

Railroader:
I have faced problems like that when I try to run one Arduino window and then an other program system, Estlcam. That is because the PC allocates/connects the COM port to the first ot those systems. Then that port is locked and the second system can not open that COM port. I do like this: Pull out the USB connector, and put it back when You hear the signal from the PC noticing that the USB port was disconnected. Then open the system You want to run.

Thanks a lot :slight_smile:
This works for me :smiley: