I insert the serial-USB convertor into my Mac.
and under the
/dev I find the
but when I use
screen to connect it:
screen /dev/tty.wchusbserial1410 9600
there get error:
Sorry, could not find a PTY.
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Finally, I find the solution, there are a screen process not close normality.
So, in the Activity Monitor I closed it, then re-start the screen, it works.
I had a similar problem and I attempted a number of different solutions. Just wanted to share what made it work for me.
Tried to use the screen program to connect my lab PC to a Raspberry PI via the USB ports and an RS232 cable.
Ran the command screen /dev/ttyUSB0
Got the following error messages in quick succession.
"Cannot access line '/dev/ttyUSB0 for r/w: permission denied"
"Couldn't find a PTY"
I tried to look in the activity monitor to see if there are any processes running, and there was none. So this was not the problem.
Tried to change the /dev/ptmx file permissions
Ran the command ls -l /dev/ptmx
Output crw-rw-rw- 1 root root 5, 2 "datetime" /dev/ptmx
So it looked like the permission were already set. So this was not the problem either.
sudo mount devpts /dev/pts -t devpts -o mode=620
I got the message that the mounting was already done. Move on.
Ran the command - sudo usermod -a -G dialout $USER
Restarted the computer and voila, it worked. Was able to use screen program to make the connection.
Spend a few hours to figure this out. Hope this helps someone out. Peace.