UCDC_LINE_DTR
sc->sc_line |= UCDC_LINE_DTR;
sc->sc_line &= ~UCDC_LINE_DTR;
sc->sc_line[ucom->sc_subunit] |= UCDC_LINE_DTR;
sc->sc_line[ucom->sc_subunit] &= ~UCDC_LINE_DTR;
sc->sc_line |= UCDC_LINE_DTR;
sc->sc_line &= ~UCDC_LINE_DTR;
USETW(req.wValue, UCDC_LINE_DTR);
sc->sc_line |= UCDC_LINE_DTR;
sc->sc_line &= ~UCDC_LINE_DTR;
sc->sc_line |= UCDC_LINE_DTR;
sc->sc_line &= ~UCDC_LINE_DTR;
sc->sc_line |= UCDC_LINE_DTR;
sc->sc_line &= ~UCDC_LINE_DTR;