According to this, /etc/inittab has been deprecated. As suggested from this I created a /etc/init/serial-ttyS2.conf. After that I has to make the service start with the following command:
[root@sbc-l1c-pcc-00 ~]# initctl start serial-ttyS2
[root@sbc-l1c-pcc-00 ~]# ps aux | grep tty
root 7779 0.0 0.0 2016 536 ttyS2 Ss+ 13:38 0:00 /sbin/agetty/dev/ttyS2 9600 vt100
However when I try to connect no login prompt pop out, just a blank screen. I tried to restarted the serial-ttyS2 while the screen was still open and the login screen came out. And I have to do it every time I need to to connect. Does somebody have a clue why?