Library /sys$common/syshlp/dtehelp.hlb SET, DTE, /SPEED  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /SPEED=(output-rate,input-rate)

    Sets the baud rate at which the terminal receives and transmits
    data. If the input and output rates are the same, specify
    /SPEED=rate.

    Not all terminals support different input and output baud rates.
    For specific information on baud rates for your terminal, consult
    the manual for that terminal.

    The default transmission rates are installation dependent.

    The valid values for input and output baud rates are as follows:

    300, 600, 1200, 2400, 4800, 9600, 19200.