A Vevor KH-870A was given to me. I could only use it with the annoying Signmaker Software under Windows.
Basic setup
With help of a Friend I managed to pump HPGL code directly into it. The steps are relatively easy:
1. Add your user to the dialout group:
sudo usermod -a -G dialout username
2. Check which device the plotter is:
Type dmesg -w
then connect plotter USB cable to the computer
3. Make the device accessible for your user:
chmod 666 /dev/usb/...
Now you can either send HPGL directly to the plotter, or use tools like Inkscape.
Inkscape
You can send HPGL to the plotter via the menu: extensions > export > plotting.
Be aware that objects like circles and rectangles have to be converted into paths before sending code to the plotter, otherwise they will be scaled wrong.
In the pop up window, select „serial“ as connection type, but enter the device address in the „parallel“ field (no idea why it has to be like that). Afterwards you can click apply and the plotting will start immediately.
Tested on Inkscape 1.4.3