Login Problem (250' RS-232 Lines)

[Jerry Aguirre]

> We are having some trouble with long (250') terminal lines.  When the system
> is booted the login message is sent out each line.  If the terminal on one of
> these long lines is turned off, there is an echo on the line that is interp-
> reted as a login name.  After 60 seconds login times out and sends a new login
> message causing the sequence to repeat.  Considerable CPU time can be wasted
> if several lines are doing this at one time.
> 		Dan Kary
> 		North Dakota State University

With all the responses about time delays and pull-down resistors I am
supprised that no one offered the most obvious sollution.  Connect the
modem control signals.

If you connect the Data Terminal Ready (DTR) of the terminal to the Data
Set Ready (DSR) of the computer port, then the getty will not send login
messages to terminals that are turned off.  Nor will it listen to
garbage on the line.

It only takes one more wire to implement this most basic of controls and
there are several benifits.
	- The init will hang on open to a line without DSR.  Not only
	  does this save an exec of getty for unconnected lines, but it
	  becomes possible to distinguish from the ps display whether
	  there is a terminal connected to that line.
	- When a user powers off his terminal at the end of the day then
	  he is automatically logged out.  Also handy when you hang your
	  port and need to restart from login.

Three second timeouts!  Pull down resistors!  Comon people, get real.

					Jerry Aguirre @ Olivetti ATC
{hplabs|fortune|idi|ihnp4|tolerant|allegra|tymix|olhqma}!oliveb!jerry