I have an Acer M550 projector as part of my home cinema. I am trying to integrate this projector with my home automation centre (based on hass.io) and the M550 is the only piece in the puzzle which requires IR commands to turn on and off. The off is particularly flaky so I would like to control using RS232 but have run into issues. I am using an ubuntu server with a PL2303 which has the following connectors Red + 5V Black GND White RXD Green TXD I have identified the following pins in my DE-9 connector (assuming the +5V is not required) and have also tried reversing the TxD and RxD The PL2303 is connected and I have read/write permissions on /dev/ttyUSB0 [ 151.218507] usb 2-3.4.1: pl2303 converter now attached to ttyUSB0 Having received the command list from here: Projector Excel codes And setting my tty settings to 9600,8,N,1: # stty -F /dev/ttyS0 9600 -parenb cs8 -cstopb -crtscts I try this command which should power on the projector echo -e "\x2A\x20\x30\x20\x49\x52\x20\x30\x30\x31\x0D" > /dev/ttyUSB0 And also tried echo -e "* 0 IR 001\r" > /dev/ttyUSB0 But nothing happens. Any ideas where I am going wrong? Here is my full stty config: stty -F /dev/ttyUSB0 -aspeed 9600 baud; rows 0; columns 0; line = 0;intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>; eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R; werase = ^W; lnext = ^V;discard = ^O; min = 0; time = 0;-parenb -parodd -cmspar cs8 hupcl -cstopb cread clocal -crtscts-ignbrk -brkint -ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon -ixoff -iuclc -ixany -imaxbel -iutf8-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0-isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop -echoprt -echoctl -echoke -flusho -extproc If I use the command screen /dev/ttyUSB0 9600 I get a constant stream of garbage and can't seem to type anything.