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NMDM(4)		       FreeBSD Kernel Interfaces Manual		       NMDM(4)

NAME
     nmdm -- nullmodem terminal	driver

SYNOPSIS
     To	compile	this driver into the kernel, place the following line in your
     kernel configuration file:

	   device nmdm

     Alternatively, to load the	driver as a module at boot time, place the
     following line in loader.conf(5):

	   nmdm_load="YES"

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 emulation works
     independently in the two directions, controlled by	the slower 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.

FreeBSD	11.2		       January 23, 2018			  FreeBSD 11.2

NAME | SYNOPSIS | DESCRIPTION | FILES | DIAGNOSTICS | SEE ALSO | HISTORY

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