SERIAL(HW) XENIX System V SERIAL(HW)
Name
tty1[a-h] , tty1[A-H] , tty2[a-h] , tty2[A-H] - Interface to
serial ports.
Description
The tty1[a-h], tty1[A-H], tty2[a-h] and tty2[A-H] files
provide access to the standard and optional serial ports of
the computer. Each file corresponds to one of the serial
ports (with or without modem control). Files are named
according to the following conventions:
- The first number in the file name corresponds to the COM
expansion slot.
- Lower case letters indicate no modem control.
- Upper case letters indicate the line has modem control.
tty1a and tty1A both refer to COM 1, whereas tty2a and tty2A
both refer to COM 2.
For example, with a four port expansion board installed at
COM 1 and a single port board installed at COM 2, you can
access:
tty1a tty1A
tty1b tty1B
tty1c tty1C
tty1d tty1D
tty2a tty2A
Each serial port has modem and non-modem invocations. The
device names in the following table refer to the serial
ports, with and without modem control. The first section of
the table describes boards at COM 1 and the second section
describes boards installed at COM 2. ``Minor'' is the minor
device number for the port (see mknod(C)).
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SERIAL(HW) XENIX System V SERIAL(HW)
____________________________________________________
Serial Lines
____________________________________________________
Board Non-Modem
Type Control Modem Control
| Minor Name Minor Name |
|___________________________________________________|
| | |
| | | 1 Port 0 tty1a 128 tty1A|
| | _________ |
| | | 1 | tty1b| 129 | tty1B|
| | | 2 | tty1c| 130 | tty1C|
| | 4 Port | | | | |
| | | 3 | tty1d| 131 | tty1D|
| ______________| | | | |
| | 4 | tty1e| 132 | tty1E|
| | 5 | tty1f| 133 | tty1F|
| 8 Port | 6 | tty1g| 134 | tty1G|
| | 7 | tty1h| 135 | tty1H|
| | | | | |
|___________________|_______|_______|_______|_______|
| | | | | | |
| | | 1 Port | 8 | tty2a| 136 | tty2A|
| | ________| | | | |
| | | 9 | tty2b| 137 | tty2B|
| | | 10 | tty2c| 138 | tty2C|
| | 4 Port | | | | |
| | | 11 | tty2d| 139 | tty2D|
| ______________| | | | |
| | 12 | tty2e| 140 | tty2E|
| | 13 | tty2f| 141 | tty2F|
| 8 Port | 14 | tty2g| 142 | tty2G|
| | 15 | tty2h| 143 | tty2H|
| | | | | |
|___________________|_______|_______|_______|_______|
| | | | | |
| | 16 | tty2i| 144 | tty2I|
| | 17 | tty2j| 145 | tty2J|
| | 18 | tty2k| 146 | tty2K|
| | 19 | tty2l| 147 | tty2L|
| 16 Port (MCA) | 20 | tty2m| 148 | tty2M|
| | 21 | tty2n| 149 | tty2N|
| | 22 | tty2o| 150 | tty2O|
| | 23 | tty2p| 151 | tty2P|
| | | | | |
|___________________|_______|_______|_______|_______|
Interrupt Vectors:
All board(s) installed at COM 1 - 4
All board(s) installed at COM 2 - 3
For a list of I/O addresses, see the Release Notes furnished
with your distribution.
Access
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SERIAL(HW) XENIX System V SERIAL(HW)
The files may only be accessed if the corresponding serial
interface card is installed and its jumper I/O address
correctly set. Also, for multi-port expansion cards, you
must use the mkdev(ADM) program to create more than the
default number of files.
The serial ports must also be defined in the system
configuration. Check your hardware manual to determine how
your system is configured, via a CMOS database or by switch
settings on the main system board. If your system is
configured using a CMOS database, the ports are defined in
the database (see cmos(HW)). Otherwise, define the ports by
setting the proper switches on the main system board. Refer
to your computer hardware manual for switch settings.
It is an error to attempt to access a serial port that has
not been installed and defined.
The serial ports can be used for a variety of serial
communication purposes such as connecting login terminals to
the computer, attaching printers, or forming a serial
network with other computers. Note that a serial port may
operate at most of the standard baud rates, and that the
ports (on most computers) have a DTE (Data Terminal
Equipment) configuration. The following table defines how
each pin is used for 25-pin and 9-pin connections:
__________________________________________________
| 25-Pin| 9-Pin| Description |
|_______|_______|_________________________________|
| 2 | 2 | Transmit Data |
|_______|_______|_________________________________|
| 3 | 3 | Receive Data |
|_______|_______|_________________________________|
| 4 | 7 | Request to Send |
|_______|_______|_________________________________|
| 5 | 8 | Clear to Send |
|_______|_______|_________________________________|
| 7 | 5 | Signal Ground |
|_______|_______|_________________________________|
| 8 | 1 | Carrier Detect (Data Set Ready)|
|_______|_______|_________________________________|
| 20 | 4 | Data Terminal Ready |
|_______|_______|_________________________________|
Only pins 2, 3, and 7 (2,3 and 5 for 9-pin) are necessary
for a terminal (or direct) connection.
A modem control device (port) uses pins 2, 3, and 7 in the
same way as a non-modem control device: send on pin 2 and
receive on pin 3. Pin 7 is data ground. On a non-modem
control device the state of the other pins are not set or
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SERIAL(HW) XENIX System V SERIAL(HW)
read. On a modem control device, pins 4 and 20 (RTS & DTR)
are asserted and the port will not open until pin 8 (CXD) is
asserted. That is, no signal travels from pin 2 until pin 8
is asserted from another source. The modem control device
monitors the the status of pin 8.
See tty(M) and termio(M) for the details of serial line
operation in the system.
Files
/dev/tty1[a-h]
/dev/tty1[A-H]
/dev/tty2[a-h]
/dev/tty2[A-H]
See Also
cmos(HW), csh(C), cu(C), getty(ADM), mkdev(ADM), mknod(C)nohup(C), open(S), termio(M), tty(M), uucp(C)
Notes
If you login via a modem control serial line, hanging up
logs that line out and kills your background processes. See
nohup(C) and csh(C)).
You cannot use the same serial port with both modem and
non-modem control at the same time. For example, you cannot
use tty1a and tty1A simultaneously.
Use a modem cable to connect your modem to a computer.
Page 4 (printed 2/7/91)
