# stty doesn't work ??



## vietchau (Jan 28, 2008)

Hi,
I have a Mac Book OS X and a usb to rs232 adapter. I have downloaded the FTDI driver and everything seems to work except I can't the baud rate of the line to any speed except the default 9600. 
I did this command on bash shell : 
stty -f /dev/tty.usbserial speed 115200 
--> it prints out the number : 9600 

a subsequence stty -f shows the baud rate is still 9600 ??. 


I can set up the serial line using minicom but after quitting minicom (Ctr-A Q without resetting) , the baud rate switches back to 9600 ??. Can anyone give me some advices on how to solve this problem ?


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## hephaestus (Mar 23, 2011)

Bumping this old post that never received a response. I'm encountering essentially the same problem, and despite scouring the various Mac OS X support forums out there, have yet to find an answer/solution/workaround.


I have a USB-to-serial converter cable that has the Prolific chepset, and that uses the osx-pl2303.kext driver. I know that the cable and driver work, because I'm able to connect to an external device (a TNC = packet radio modem) connected via this cable, using the *screen* program (a VT100 terminal emulator). Using *screen*, I can type at the modem's command prompt, and it sends me back reasonable answers.

On the other hand, I'm having no luck using the *stty* command to change the baud rate of the USB-serial device (/dev/cu.PL2303-0000201A), which I need to do so that I can run a different program that wants to communicate with/control the TNC. The *screen* program is able to set the baud rate of the device to a value provided on the command line, so I know that the baud rate is changeable. But *stty* consistently fails, without complaint, to change the baud rate:

*hephaestus$ su*
*Password: *
*sh-3.2# stty -f /dev/cu.PL2303-0000201A* 
speed 9600 baud;
lflags: -icanon -isig -iexten -echo
iflags: -icrnl -ixon -ixany -imaxbel -brkint
oflags: -opost -onlcr -oxtabs
cflags: cs8 -parenb
*sh-3.2# stty -f /dev/cu.PL2303-0000201A 19200*
*sh-3.2# stty -f /dev/cu.PL2303-0000201A* 
speed 9600 baud;
lflags: -icanon -isig -iexten -echo
iflags: -icrnl -ixon -ixany -imaxbel -brkint
oflags: -opost -onlcr -oxtabs
cflags: cs8 -parenb

Am I invoking stty incorrectly, or is there just a bug in it? (Or is some third thing happening that I'm not considering?)

I am running 10.5.8 on a MacBook Pro with 2.4 GHz Intel Core 2 Duo.

Thanks, 

Michael


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