Version vom 9. Mai 2014, 18:33 Uhr

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Serial Port Tips for Linux

Set the default configuration with stty to 9600 bps, 8N1, no flow control:

stty -F /dev/serial_port cs8 -parenb -cstopb -clocal raw speed 9600

 # What the arguments mean:
 #   cs8:     8 data bits
 #   -parenb: No parity (because of the '-')
 #   -cstopb: 1 stop bit (because of the '-')
 #   -clocal: Disable modem control signals

No exclusive lock when accessing serial ports

I was surprised to learn that several Linux processes can open a given serial port at the same time. This usually makes a mess of the data. If you make a mistake and try to use the same port from several concurrent scripts, it may take a while to figure out why the data is getting chopped and mixed up in random ways.

There is no exclusive lock when opening serial port files, like there is under Windows. As far as I know, there is no way to enforce such a protection against concurrent access at system level. If you do know how to achieve that, please drop me a line!