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Linux connection problem

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Cura can upload new firmware fine, but cannot connect for me.

I get this error:

cura trying baudrate 250000

There is some comment here (which does not work for me):


I am using Linux Mint which has python-serial 2.6, and the patch explanation above seems to only work for python 2.7 and python3.

I have tried Cura 13.06.5 and 13.10 without luck.

What steps should I do to be able to connect to the UM from Linux?


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250000 baud is a problem on Linux. I added a patch to the latest git version of Cura which might help, but I have not had reports that it works.

You can install the 115200 baudrate firmware, this should fix the connecting problem. It installs as default firmware if you run on linux.

(And the patch should work. PySerial is at version 2.6, but your Python version is 2.7, as Cura needs python 2.7)


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The default baudrate on the latest github Cura (yesterday) was set to 250000, so initially starting Cura failed on the initial machine test.

It connects now when I change that as follows:

File -> Machine Settings -> Baudrate = 115200


Expert -> Run first run wizard


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The connection stopped working for some odd reason.

If I set the serial port to the actual one wired to the UM (/dev/ttyACM0) then the SD card icon replaces the Print icon. I assume that the print icon disappears because Cura cannot connect to ttyACM0.

If the serial port is set to AUTO, then the Print icon shows up (with no SD icon), Clicking on the Print icon is doing something to the machine (slight sounds heard from the machine), but the connection fails with the following error log:

Changing monitoring state from 'Offline' to 'Detecting serial port'

Serial port list: [u'/dev/ttyACM0', '/dev/ttyUSB2', '/dev/ttyUSB0', '/dev/ttyUSB1']

Connecting to: /dev/ttyACM0

Error while connecting to /dev/ttyACM0: 'Timeout'

Connecting to: /dev/ttyUSB2

Error while connecting to /dev/ttyUSB2: 'Timeout'

Connecting to: /dev/ttyUSB0

Error while connecting to /dev/ttyUSB0: 'Failed to open serial port'

Connecting to: /dev/ttyUSB1

Error while connecting to /dev/ttyUSB1: 'Timeout'

Failed to open serial port (AUTO)

Changing monitoring state from 'Detecting serial port' to 'Error: Failed to autodetect...'

dmesg shows that ttyACM0 was connected (when I initially plugged in the cable):

[273450.701652] usb 8-1: new full-speed USB device number 11 using uhci_hcd

[273450.903657] usb 8-1: New USB device found, idVendor=2341, idProduct=0042

[273450.903662] usb 8-1: New USB device strings: Mfr=1, Product=2, SerialNumber=220

[273450.903665] usb 8-1: Manufacturer: Arduino (www.arduino.cc)

[273450.903667] usb 8-1: SerialNumber: 7523031373335151A120

[273450.905767] cdc_acm 8-1:1.0: ttyACM0: USB ACM device



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The auto-serial-port detection tries to find an Arduino Mega2560 bootloader. It might not find that for some reason, you could set the serial port from AUTO to ttyACM0, might help, this also sets longer timeouts on a few things (helps with none-Ultimaker hardware seen in RepRaps)


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The AUTO setting worked once today, but failed later. I tried setting to ACM0 and only the floppy disk icon shows now (with no SD card installed). Further tests with AUTO turned on shows the print icon, but the connection always fails.

As a side note comparison, Pronterface does connect to ACM0 and completes the entire print connected to the UM.

To confirm, I am not running Cura (13.10) and Pronterface (2013.08.17) at the same time, so there should be no connection conflict.

Are there any other tests or log files I can provide to help?


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