socket and serial port

[Mark Wieder]

Dar-

You're correct about the way the handshaking normally works. And that
the dtr/rts lines are used to supply power.

But for some reason the x10 serial programmers decided to create a
whole new standard which ignores the data lines. Don't ask me why. My
guess is that it's so that x10 communications don't interfere with a
datastream to another device piggybacked onto the controller.

What you end up with is the following:

standby mode: dtr=on rts=on
reset:        dtr=off rts=off
bit one:      dtr=off rts=on
bit zero:     dtr=on rts=off

At least one of (dtr or rts) must be on in order to supply power to
the device, or else it resets and the serial string must be resent.
This causes problems in runrev since there's no way from Transcript to
toggle either dtr or rts without closing the port (which has the
effect of turning both dtr and rts off, effectively reseting the
sending device).

-- 
-Mark Wieder
 mwieder at ahsoftware.net