Connect GRBL cnc to LMDE via USB

[petelodge89]

I am trying to connect LMDE to my GRBL arduino based cnc via usb, I want to install LMDE on my old mac to control the cnc via UGS Platform I am getting an error message when I try and connect error opening connection. could not connect to controller on port jserial.com://ACMO:115200. I have looked at posts elsewhere and I have tried some suggested terminal commands which showed error messages ie the commands were not correct for LMDE ie sudo chmod a+rw/dev/ttyUSBO ! Can anyone suggest how I might get the comms to work over USB. Many thanks

[Schildkroet]

Make sure you have sufficient rights
https://unix.stackexchange.com/questions/14354/read-write-to-a-serial-port-without-root

[petelodge89]

I tried sudo usermod -a- G dialout $user but that did not help. All I want to do is connect my cnc arduino controller to UGS platform, then I will do a full install wiping out mac os. All I use this imac for is the cnc. I have zero technical knowledge of unix, I don't really need it, I hope for this one task ! cheers, Pete

[breiler]

Are you certain that your Arduino is properly flashed with GRBL? Using the Arduino IDE, have you tried connecting to the device from the serial monitor?

[petelodge89]

The system works fine under the older version of mac os running on this imac connected via usb, so I had hoped that LMDE would just connect the same way with the existing usb connection. Why would it do anything else, USB is USB

[breiler]

Disconnect your Arduino and connect it again then run this sudo dmesg to make sure that the device you are connecting to is properly identified.

It should output something like this:

[  181.711150] usb 1-9.2: new full-speed USB device number 15 using xhci_hcd
[  181.829907] usb 1-9.2: New USB device found, idVendor=2a03, idProduct=0043, bcdDevice= 0.01
[  181.829924] usb 1-9.2: New USB device strings: Mfr=1, Product=2, SerialNumber=220
[  181.829930] usb 1-9.2: Product: Arduino Uno
[  181.829935] usb 1-9.2: Manufacturer: Arduino Srl            
[  181.829939] usb 1-9.2: SerialNumber: 85435333231351402161
[  181.854519] cdc_acm 1-9.2:1.0: ttyACM0: USB ACM device
[  181.854583] usbcore: registered new interface driver cdc_acm
[  181.854587] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

Then run this to make sure it has the right group permissions ls -al /dev/ttyACM0. Should output something like:

crw-rw----+ 1 root dialout 166, 0 dec 31 12:44 /dev/ttyACM0

Then run this command to make sure you have the proper group rights groups. This should include the dialout group.

Make sure you don't have brltty install, read this for more info:
arduino/help-center-content#155

[petelodge89]

Hi Joacim, thank you very much for your help. I have run sudo dmesg and it did indeed output the strings.as you show. I then ran the -al command it ouputted the string as you show but the /dev/tty/ACM0 is in yellow. You then ask me to run a command to determine if I have the correct group right, but no command is shown. I am working off an iso on a memory stick, I have checked and I can't see Britty. Many thanks, Peter

[breiler]

You then ask me to run a command to determine if I have the correct group right, but no command is shown.

What is the output when you run groups from the terminal?

I have checked and I can't see Britty.

How did you check? Did you run ps -C brltty?

[petelodge89]

when I run groups, I get mint cdrom sudo audio dip video plugdev users netdev bluetooth scanner, when I run sudo ps -C brltty I get PID TTY TIME CMD

[breiler]

I then ran the -al command it ouputted the string as you show but the /dev/tty/ACM0 is in yellow.

Since you didn't give me the actual output I will have to assume it has the group rights for the dialout group which is not in your list of assigned groups: mint cdrom sudo audio dip video plugdev users netdev bluetooth scanner

This means that you didn't successfully add your user to the group, normally you need to logout/login for it to take effect in the whole user session:
usermod -a -G dialout $USER

I am working off an iso on a memory stick

This is probably a bad idea as the group settings you make are not persisted.