ucom_line_state
ucom_line_state(sc, UCOM_LS_RING, 0);
ucom_line_state(sc, 0, UCOM_LS_RING);
ucom_line_state(sc, UCOM_LS_BREAK, 0);
ucom_line_state(sc, 0, UCOM_LS_BREAK);
ucom_line_state(sc, UCOM_LS_DTR, 0);
ucom_line_state(sc, 0, UCOM_LS_DTR);
ucom_line_state(sc, UCOM_LS_RTS, 0);
ucom_line_state(sc, 0, UCOM_LS_RTS);