Port busy when opening serial port on Ubuntu Linux 12.04 LTS about java-simple-serial-connector HOT 6 CLOSED

To solve this problem you must either run the program as root, add the current 
user to the group that /dev/ttyUSB0 belongs to (mine is 'dialout', although 
this didn't seem to work for me), or change permissions on the ttyUSB0 folder, 
although this may change once the computer is restarted/device unplugged

eg. chmod -R 777 /dev/ttyUSB0

I've found you need to give 7's (read, write, and execute) for it to work. But 
I am by no means an expert - if somebody has a better solution please feel free 
to correct me

I experienced the following with Ubuntu 12.10 (and also with 12.04 LTS):

On my system the culprit was modem-manager blocking the serial port after 
plugging in my FTDI (USB virtual serial) device. I got the "Port busy" 
exception for ~ 30 seconds. Then the port was accessible again. After a 
"apt-get purge modemmanger" everything is fine now. The port is accessible 
immediately after plugging the device.

In case the problem was with COM1 AKA /dev/ttyS0

Using chmod -R 777 /dev/ttyS0 only solves the problem until reboot, because the 
permissions will be reset. 

using  "ls -l /dev/ttyS0" I found out that the user group "dialout" has 
permissions on the "file", so I just added my user to that group and my problem 
was solved

Hope this helps

I've resolved this problem with:

chmod -R 777 /dev/ttyS0

Thanks :)

Hi every one, My name is Gopinath, i want connect weighbrige in ubuntu 10.04 
via the serial port. i want to read the weight using Java. please any one help 
me to do this.

Os: Ubuntu 10.04
Language : Java 1.7.0

Which library is easy to read, and how i can read the data, please assist me...


Thanks and Regards
Gopinath R