See
	ttyflags(8)
	ttys(5)

In /etc/ttys, you can set the state of a port (e.g. "local"), and
ttyflags(8) gets invoked at boot time. So, this is partly a system
configuration issue; you can change it and run ttyflags yourself (so that
you don't have to reboot).

The other question is whether you've got the serial cable wired right; I
don't think that the Sun serial ports are wired to do anything with RI -
what does the X-10 box use it for?

	Erik <fair@clock.org>