Ultimaker Cura 4.11 doesn't allow selection of the ttyUSB port

[lesh 0]

My computer is a Toshiba laptop running Ubuntu 20.04, my printer is a Creality CR10S.  My Linux is up to date.

I replaced the motherboard for my printer, a Creality CR10S.  I couldn't get Ultimake Cura to find it.  After much googling around, and some low level type work on my laptop, I discovered that the connection was on ttyUSB0, and that using Arduino GUI terminal function, the board was working at 115200 baud.  Then I went to GitHub and retrieved the software for Ultimaker

In the software source code I found: 

The line that shows this is in the Ultimaker source code: .  
the file is Cura-master/plugins/USBPrinting/USBPrinterOutputDeviceManager.py

133            # set CURA_DEVICENAMES=USB[1-9] -> e.g. not matching /dev/ttyUSB0
134            pattern = environ.get('CURA_DEVICENAMES')
135           if pattern and not search(pattern, port[0]):
136                continue

 

There are several issues with this.  First of all, port scanning is very poor practice.  If ports are in use, the system can be disrupted and may result in catastrophic failures, especially in systems used for production.  Second, it presupposes the way ports are named.  Thus a change in the OS would demand a change in your software.  The better approach is like that of Android where you can choose the port from a list, and for production, an editable entry in the configuration with appropriate comment on port selection.

[GregValiant 980]

Since no Ultimaker printers use "USB printing" the plugin has not seen any updates or fixes for years and my understanding (after reading posts here and on GitHub) is that it isn't likely to be updated.  The main alternative is using RaspberryPI and Octoprint.

The problems that occur when printing via USB are not unique to Cura.  Pronterface and Repetier Host have issues as well.  I was sort of enamored with printing via USB and tried to write my own program.  It quickly turned into a quagmire and I ended up throwing it all away in favor of a program that is a front end for the printer and controls the printing from the SD card.  It's much better when the printer can just pull the next line of code when it needs it rather than going through buffer over-runs and under-runs.