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serial(7)							     serial(7)

NAME    [Toc]    [Back]

     serial - serial communication ports

SYNOPSIS    [Toc]    [Back]


DESCRIPTION    [Toc]    [Back]

     All Silicon Graphics systems have two or more general purpose serial
     ports.  These ports can be	used to	connect	terminals, printers, modems,
     other systems, or graphical input devices such as a tablet	or dial	and
     button box.  Each line can	be independently set to	run at any of several
     speeds.  Various character	echoing	and interpreting parameters can	also
     be	set.  See stty(1) and termio(7)	for details on the various modes.

     Details of	the serial ports found on optional add-on boards are given
     elsewhere.	 The Audio/Serial Option for CHALLENGE/Onyx provides six
     high-speed	serial ports, see asoser(7) for	more information.  The CDSIO
     VME board provides	six serial ports; see cdsio(7) for more	information.

     Special files for the serial ports	exist in the /dev directory. These
     files are named tty<type><portno>,	where type is one or more characters
     indicating	the type of interface to the hardware that this	file provides,
     and portno	is a number identifying	the physical port. The descriptions
     below indicate among other	things which hardware signals are used by each
     port type.	For more details on this see SOFTWARE USAGE below. Currently
     supported types include:

     d	  e.g. ttyd1. This is the most basic serial port type. It supports
	  TD/RD	only.

     m	  e.g. ttym1. This port	type provides modem control. It	supports TD/RD
	  and DCD/DTR.

     f	  e.g. ttyf1. This port	type provides modem and	flow control. It
	  supports TD/RD, DCD/DTR and RTS/CTS.

     The following types are supported on O2, OCTANE, Origin2000/200, Onyx2
     and Challenge/Onyx	systems:

     c	  e.g. ttyc1. This port	type provides a	raw character device interface
	  to the hardware. It is intended for applications which wish to do
	  bulk data transfer with minimal overhead and no data interpretation.
	  Since	this is	not a streams device and no line discipline exists,
	  streams or line discipline related ioctl commands may	fail or
	  silently have	no effect. See cserialio(7) for	details.  This port
	  type supports	only TD/RD by default but RTS/CTS flow control may be
	  enabled via ioctl if the hardware supports it.

     4d	  e.g. tty4d1. This port type enables RS422 (Appletalk)	mode. It uses
	  TxD+/-, RxD+/-. On Challenge/Onyx, every 4th port (tty4d4, tty4d8,
	  etc.)	is hardwired to	RS422 and other	ports are hardwired to RS232,
	  so this port type only exists	for every 4th port.

									Page 1

serial(7)							     serial(7)

     4f	  e.g. tty4f1. This port type enables RS422 (Appletalk)	mode including
	  the handshake	signals. It uses TxD+/-, RxD+/-, HSKo and HSKi.	On
	  Challenge/Onyx, every	4th port (tty4d4, tty4d8, etc.)	is hardwired
	  to RS422 and other ports are hardwired to RS232, so this port	type
	  only exists for every	4th port.

     midi e.g. ttymidi1. This port type	provides a midi	interface to the
	  serial device. See midi(3).

     The following type	is supported on	O2, OCTANE, Onyx2 and Origin2000/200

     us	  e.g. ttyus1. This port type provides a user mapped interface to the
	  hardware, allowing reading and writing of bytes without any system
	  call overhead. Use of	this port requires installation	of the
	  react.sw.usio	subsystem of REACT/Pro.	See usio(3) for	details.

     The portno	component of the tty filename identifies the actual hardware
     accessed by the device file. All tty files	with the same port number
     access the	same hardware, i.e. ttyd1, ttyc1 and ttymidi1 all access the
     same physical port. A given tty device may	be opened any number of	times,
     but only one interface type may be	opened to the same physical port at a
     time, e.g.	if ttyd1 is open, access will be denied	to ttyf1 or ttyc1.

     On	Onyx2 systems with console set to d, and on Origin2000 and Origin200
     systems, the console port and its twin are	guaranteed to be ports 1 and
     2,	all other ports	are dynamically	assigned port numbers as per the whims
     of	ioconfig(1). It	may be necessary to obtain the absolute	path of	the
     port in the filesystem by resolving links until a true device is found in
     order to determine	where on the machine the port is actually located.


     There are five different types of connectors found	on various 4D models.
     Note that in terms	of connectors and pin assignments, the Challenge S is
     identical to the Indy and both Challenge M	and Power Challenge M are
     equivalent	to the Indigo2.	 The DB-9 male serial port connectors on O2,
     OCTANE, Onyx2, Origin2000 and Origin200 systems have the following	IBM(R)
     PC/AT(tm)-like pin	assignments:

				\  1  2	 3  4  5  /
				 \   6	7  8  9	 /

			 Pin | Name | Description
			  1  | DCD  | Data Carrier Detect
			  2  | RD   | Receive Data
			  3  | TD   | Transmit Data
			  4  | DTR  | Data Terminal Ready
			  5  | GND  | Signal Ground

									Page 2

serial(7)							     serial(7)

			  6  | -    | reserved
			  7  | RTS  | Request To Send
			  8  | CTS  | Clear To Send
			  9  | -    | reserved

     The ports on OCTANE, Onyx2, Origin2000 and	Origin200 systems can be set
     by	software to an Appletalk-compatible RS-422-like	mode, in which they
     have the following	pin assignments:

			   Pin | Name |	Description
			    1  | -    |	reserved
			    2  | RxD- |	Receive	Data -
			    3  | TxD- |	Transmit Data -
			    4  | TxD+ |	Transmit Data +
			    5  | GND  |	Signal Ground
			    6  | RxD+ |	Receive	Data +
			    7  | HSKo |	Output Handshake
			    8  | HSKi |	Input Handshake
			    9  | -    |	reserved

     The DB-9 female serial port connectors, which are found on	the CHALLENGE
     and Onyx systems, have the	following pin assignments.

				\  5  4	 3  2  1  /
				 \   9	8  7  6	 /

			  2  | TD   | Transmit Data
			  3  | RD   | Receive Data
			  4  | RTS  | Request To Send
			  5  | CTS  | Clear To Send
			  7  | SG   | Signal Ground
			  8  | DCD  | Data Carrier Detect
			  9  | DTR  | Data Terminal Ready

     The CHALLENGE and Onyx systems provide an RS-422 port.  This RS-422 port
     uses a DB-9 female	serial connector and has the following pin

			 Pin | Name | Description
			  1  | DTR  | Data Terminal Ready
			  2  | TxD- | Transmit Data -
			  3  | RxD- | Receive Data -
			  4  | DCD  | Data Carrier Detect
			  5  | CTS  | Clear To Send
			  6  | SG   | Signal Ground
			  7  | TxD+ | Transmit Data +

									Page 3

serial(7)							     serial(7)

			  8  | RxD+ | Receive Data +
			  9  | RTS  | Request to send

     In	order to support peripherals that draw power from the host system, the
     CHALLENGE and Onyx	systems	provide	two powered-peripheral serial ports.
     These ports have a	DIN-8 connector.  The powered ports share the tty2 and
     tty3 signal lines with the	standard DB-9 connectors; if the DB-9
     connector for tty2	is already in use, you cannot use the powered
     peripheral	connector for tty2.  Similarly,	if tty3's DB-9 connector is
     connected to a peripheral,	the powered peripheral port connected to the
     tty3 signal lines cannot also be used.  The powered peripheral ports have
     the following pin assignments.

				     /	 2   \
				    /4	     5\
				   /	       \
				  ( 1	 8    3	)
				   \	       /
				    \ 6	    7 /

			Pin | Name   | Description
			 1  | DTR    | Data Terminal Ready
			 2  | CTS    | Clear To	Send
			 3  | STEREO | Stereo field sync
			 4  | RD     | Receive Data
			 5  | TD     | Transmit	Data
			 6  | SG     | Signal Ground
			 7  | GND    | Ground point
			 8  | V10P   | 10V supply

     The DIN-8 serial port connectors on the Indigo, Indy, Indigo2, Challenge
     S,	Challenge M, Power Challenge M,	and the	MENET 4-Enet, 6-serial board
     (XT-FE-4TX-6A) have the following pin assignments.

				    / 8	 7  6 \
				   (  5	 4  3  )
				    \  2   1  /

		      Pin   | Name    |	Description
		       1    | DTR     |	Data Terminal Ready
		       2    | CTS     |	Clear To Send
		       3    | TD      |	Transmit Data
		       4    | SG      |	Signal Ground
		       5    | RD      |	Receive	Data

									Page 4

serial(7)							     serial(7)

		       6      RTS	Request	To Send
		       7    | DCD     |	Data Carrier Detect
		       8    | SG      |	Signal Ground

		 Macintosh SE Compatible Pin Assignments (RS-422)
		  1   |	HSKo  |	Output Handshake
		  2   |	HSKi  |	Input Handshake	Or External Clock
		  3   |	TxD-  |	Transmit Data -
		  4   |	GND   |	Signal Ground
		  5   |	RxD-  |	Receive	Data -
		  6   |	TxD+  |	Transmit Data +
		  7   |	GPi   |	General	Purpose	Input
		  8   |	RxD+  |	Receive	Data +

SOFTWARE USAGE    [Toc]    [Back]

     The set of	signals	that are actually used depends upon which form of the
     device was	opened.	 If the	ttyd name was used, only TD, RD, and SG
     signals are meaningful.  These three signals are typically	used with
     "dumb" devices that either	do not need any	sort of	data flow control or
     use software flow control (see the	description of the ixon, ixany,	and
     ixoff options in stty(1) for more information on setting up software flow
     control).	If the ttym device is used, the	DCD, and DTR signals are also
     used.  These signals provide a two	way handshake for establishing and
     breaking a	communication link with	another	device and are normally	used
     when connecting via a modem.  When	the port is initially opened, the host
     asserts the DTR line and waits for	the DCD	line to	become active.	If the
     port is opened with the O_NDELAY flag, the	open succeeds even if the DCD
     line is not active.  A hangup condition occurs if the DCD line
     transitions from active to	inactive.  See open(2),	and termio(7) for more
     information.  If the ttyf device is used, all of the signals are used.
     The additional signals provide for	full hardware flow control between the
     host and the remote device.  The RTS line is asserted by the host
     whenever it is capable of receiving more data.  The CTS line is sampled
     before data is transmitted	and if it is not active, the host suspends
     output until it is.

     The DIN-8 serial port connectors on the Indy, Challenge S,	Indigo2,
     Challenge M, Power	Challenge M, and MENET 4-Enet, 6-serial	board (XT-FE4TX-6A)
 can be used to communicate	with serial devices using RS-422
     protocol.	User can use the stream	ioctl commands,	SIOC_EXTCLK and
     SIOC_RS422, defined in /usr/include/sys/z8530.h to	switch between
     internal/external clock and RS-232/RS-422 protocols.  Another command
     that can be useful	is SIOC_ITIMER;	it informs the driver how long it
     should buffer up input data, in clock ticks, before sending them
     upstream.	Data can sometimes be sent upstream before, but	never after,
     this time limit.  This feature reduces the	cpu cost of receiving large
     amounts of	data by	sending	data upstream in large chunks.	This duration
     can also be configured into the kernel by tuning the duart_rsrv_duration
     variable.	On Origin, Onyx2, O2 and Octane	systems, the serial hardware
     sets an input timer based on the value passed in through SIOC_ITIMER. For

									Page 5

serial(7)							     serial(7)

     soft flow control,	this input timer may result in excessively slow
     response to an XOFF request since an XOFF char is not detected by the
     software until the	hardware timer expires.	If soft	flow control skid is
     unacceptably large, it may	be necessary to	reduce the latency of the
     hardware input timer by reducing the value	passed to SIOC_ITIMER.

SUPPORTED SPEEDS    [Toc]    [Back]

     The serial	ports of all SGI systems support several standard rates	up
     through 38400 bps (see termio(7) for these	standard rates). The serial
     ports on O2, OCTANE, Origin2000, Onyx2 and	Origin200 systems also support
     bit rates up through 115200 bps, including	the following rates:

				  31250	  57600
				  76800	  115200

     Many other	rates, up to 460800, can be set.  The accuracy of actual baud
     rate set is guaranteed to be within 2.5% of the desired rate.  If this
     condition cannot be met, the command (ioctl or stty) will fail.  However,
     performance at baud rates above 115200 is not guaranteed, and their use
     is	not officially supported.

     At	baud rates above 38400,	cable length and quality become	quite
     important.	 These rates are more likely to	work in	RS-422 mode, on
     systems that support it.

     By	default, Onyx and CHALLENGE L/XL systems enable	only the serial	ports
     of	the master IO4.	 To enable the serial ports on other IO4 boards, a
     vector line must be added for the epcserial device	to
     /var/sysgen/system/irix.sm.  The following	vector line configures the
     serial ports on the IO4 in	slot 13	as tty45, tty46, and tty47:

	  VECTOR: bustype=EPC module=epcserial unit=1 slot=13

     The first two options (bustype and	module)	are mandatory and tell
     lboot(1M) that you're configuring serial ports.  The unit option
     specifies which set of tty	names should be	used for this set of ports:
     unit 1 corresponds	to the logical devices tty45, tty46, and tty47;	unit 2
     represents	devices	tty49, tty50, and tty51; unit 3	specifies devices
     tty53, tty54, and tty55.  Finally,	the slot option	indicates which	IO4
     board contains the	ports that should be mapped.  Each board must have its
     own vector	line.  Configuring one IO4 board's serial ports	has no effect
     on	any of the other boards.  After	irix.sm	has been updated, the
     autoconfig(1M) command should be issued to	reconfigure the	kernel.	 It
     may also be necessary to execute MAKEDEV(1M) in order to build device
     files for the new ports.

     If	the system is unable to	honor the VECTOR line for some reason (if, for
     example, the specified slot is invalid), a	warning	message	is written to
     /var/adm/SYSLOG.  These warning messages contain the string epcserial, in
     order to facilitate finding them with commands like grep(1).  Because the
     console port has not been initialized when	these messages are issued, the

									Page 6

serial(7)							     serial(7)

     kernel is unable to display the warning on	the console.

     Only the master IO4 provides an RS-422 port (tty4).  Additional IO4
     boards support three RS-232 serial	ports only.  To	allow for future
     expansion,	however, space was left	in the serial port namespace for the
     additional	RS-422 ports.  For this	reason,	there is no actual device
     associated	with tty48, tty52, and tty56.

FILES    [Toc]    [Back]


SEE ALSO    [Toc]    [Back]

     system(4),	asoser(7), cdsio(7), keyboard(7), streamio(7), termio(7),
     termios(3), cserialio(7), usio(3).

									PPPPaaaaggggeeee 7777
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