pyserial Raspberry works on Raspbian but doesn't work on Arc

[mangelic]

Hi everyone, I am new on Arch and I have installed the pyserial module for python. I want to use raspberry pi UART with Xbee modules. First of all, the system and hardware works fine in raspbian and now I want to change the OS. I installed the packages python and python2 and I disabled the serial console with "systemctl disable getty@ttyAMA0.service" "systemctl stop getty@ttyAMA0.service" commands. I have already commented the line on /boot/config.txt "console=ttyAMA0 etc...". The problem is that when I test the serial port using a loopback (Tx connected directly with Rx) works fine but when I connect the Xbee I can send messages but not receive them. I use the "_init_" function in the pyserial module to configure baudrate and parity and timeout bla bla. But it seems to fail and doesn't match with Xbee config. Hardware is not a problem because in raspbian works great, it seems to be a software issue. Could somebody help me?
Thanks and regards!