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10. How Do I Set Up My Serial Ports For Higher Speeds? What Speed Should I Use With My Modem?

This section should help you figure out what speed to use when using your modem with a communications program, or with a getty program. Normally you just set the speed by a parameter given to getty or by a menu in your communications program (or in a configuration file). If for some reason that doesn't work for high speeds, there is a workaround by giving special options to setserial: With the spd_hi or spd_vhi options given to setserial, setting 38400 will actually set the speed to 57600 (spd_hi) or 115200 (spd_vhi).

Make sure you have at least 16550A UARTs for higher speeds. Here are some suggested speeds:

If you use setserial test them on the command line first, and then when you have them working, put them into /etc/rc.d/rc.serial or /etc/rc.d/rc.local or /etc/rc.boot/0setserial so that they are run at startup. Make sure that you are using a valid path for setserial, and a valid device name. You can check the settings of a serial port by running:

setserial -a /dev/ttyS3


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