change the baud rate stty on MAC terminal

Question

I need to use USB serial cable with baud rate of 115200. I tried to set the rate with stty command from MACbook terminal application as follows;

$stty -f /dev/tty.usbserial-A103BTIB 115200

and confirmed the settings as follows;

$stty -f /dev/tty.usbserial-A103BTIB -a

&speed 9600 baud; 0 rows; 0 columns;
lflags: -icanon -isig -iexten -echo -echoe -echok -echoke -echonl
    -echoctl -echoprt -altwerase -noflsh -tostop -flusho -pendin
    -nokerninfo -extproc
iflags: -istrip -icrnl -inlcr -igncr -ixon -ixoff -ixany -imaxbel -iutf8
    -ignbrk -brkint -inpck -ignpar -parmrk
oflags: -opost -onlcr -oxtabs -onocr -onlret
cflags: cread cs8 -parenb -parodd hupcl -clocal -cstopb crtscts -dsrflow
    -dtrflow -mdmbuf
cchars: discard = ^O; dsusp = ^Y; eof = ^D; eol = <undef>;
eol2 = <undef>; erase = ^?; intr = ^C; kill = ^U; lnext = ^V;
min = 1; quit = ^\; reprint = ^R; start = ^Q; status = ^T;
stop = ^S; susp = ^Z; time = 0; werase = ^W;

It looks baud rate is till 9600. Could somebody show me how to change this step by step ?

Ressler

Read the man page. For OSX you need to precede the desired baudrate number with the keyword speed. – Chasteen

typed stty -f /dev/tty.usbserial-A103BTIB speed 115200 but still 9600.... – Ressler

Did you read the man page? I can only find the OSX 10.9 man pages online. What version are you using? – Chasteen

Yes, I did. I use OSX 10.10. Do you change the baud speed with stty with OSX 10.9 ? Any possibility that this is an authorization problem ? – Ressler

I don't use OSX. If you mean permissions, then maybe. – Chasteen

I usually do something like this: exec 3<> /dev/cu.usbserial-AL02BXNR and then the stty command. I think the baud rate only sticks if the port is opened. – Franni

@Chasteen Yes I did read the man page. Still had to come here. – Medic

@Franni interesting (and not part of the man page) Of course that means the port is open for as long as the terminal is open. – Medic

Answer 1

It seems like this is a common problem of stty command in OSX and not solved.

https://discussions.apple.com/thread/3798003?tstart=0

Ressler

Answer 2

I was able to set the baudrate temporarily by running screen session

$ screen /dev/cu.usbserial-FTHHQD0C 115200

and opening another terminal to run my script.

Sheeb

This is also useful if you want to talk to the serial port using screen (and need the changed speed) – Trihedral

Answer 3

Other option to set a rigid baud value is to:

1. Launch a connection with the usbserial port, redirecting the output by cat in separate terminal window (to keep the port open):

cat -v /dev/tty.usbserial-A103BTIB

2. Set the baud:

stty -f /dev/tty.usbserial-A103BTIB 115200

The baud value stays set.

Tlingit