@Yveaux I see. Well I added the request() call to my sensor and the perl script is picking it up. However, it is not able to write to the serial device I guess?
20160201-12:14:57 RX: [105;4;2;0;2; ] fr=105 ci=004 c=C_REQ st=V_LIGHT noack -> Subscribe to '/mySensors/105/4/V_LIGHT'
20160201-12:14:57 [Subscribe '/mySensors/105/4/V_LIGHT']
20160201-12:14:57 TX: [105;4;1;0;2;0 ] fr=105 ci=004 c=C_SET st=V_LIGHT noack '0' -> Publish to gateway '/mySensors/105/4/V_LIGHT':'0'
EV: error in callback (ignoring): Filehandle GEN0 opened only for input at /usr/local/lib/arm-linux-gnueabihf/perl/5.20.2/AnyEvent/Handle.pm line 966.
20160201-12:14:58 [105;255;3;0;15;]
pi@raspi-hab:~ $ ls -la /dev/ttyMySensorsGateway
lrwxrwxrwx 1 root root 10 Feb 1 12:14 /dev/ttyMySensorsGateway -> /dev/pts/2
pi@raspi-hab:~ $ ls -la /dev/pts/2
crw-rw---- 1 root tty 136, 2 Feb 1 12:14 /dev/pts/2
pi@raspi-hab:~ $ ps -ealf | grep mq
4 S root 17624 7825 0 80 0 - 1650 poll_s 12:14 pts/0 00:00:00 sudo ./mqttGateway2.pl --serial /dev/ttyMySensorsGateway
4 S root 17631 17624 0 80 0 - 3815 SyS_ep 12:14 pts/0 00:00:01 /usr/bin/perl -w? ./mqttGateway2.pl --serial /dev/ttyMySensorsGateway
0 S pi 17941 13671 0 80 0 - 1065 pipe_w 12:20 pts/4 00:00:00 grep --color=auto mq