nmdm(4)

NAME

nmdm - nullmodem terminal driver

SYNOPSIS

device nmdm

DESCRIPTION

The nmdm driver provides two tty(4) devices connected by a

virtual ``null
modem'' cable.

If either of the two tty devices have the CDSR_OFLOW bit

(``stty
dsrflow'') set in their line discipline, the nmdm device

will emulate the
speed configured in the termios(4) settings. The speed emu

lation works
independently in the two directions, controlled by the slow

er end's
termios settings (c_ispeed, c_ospeed, CS5 ... CS8, CSTOPB

and PARENB).

FILES

/dev/nmdmN[AB] nullmodem device nodes.

Where the A

node has a matching B

node.

The nmdm driver implements ``on-demand device creation'' so

simply
accessing a given instance in /dev will create it.

DIAGNOSTICS

None.

SEE ALSO

stty(1), termios(4), tty(4)

HISTORY

The nmdm driver first appeared in FreeBSD 4.4.

BSD January 27, 2005

BSD