The asyc driver supports both the
system board serial port and an additional
serial adapter simultaneously.
While up to four serial ports are supported,
the system default enables two serial ports.
If an adapter for a port is not installed,
an attempt to open it will fail.
Depending on your system processor type and UART,
the port can be programmed for a range of speeds from 50 to 115200 baud,
character length, and parity.
Output speed is always the same as input speed.
The port behaves as described in
termio(HW).
The asynchronous port is a character-at-a-time device for both input and output.
This characteristic both limits the bandwidth that can be achieved
over a serial line,
and increases the interrupt loading on the central processor.
Applications like
uucp(C)
and PPP
may be able to function well at speeds greater than 9600 baud,
depending on your system processor type and UART.
The serial port adapter's programmable baud rates do not
correspond exactly with system baud rates.
Specifically, setting B0 will cause a disconnect,
setting EXTA will set 19200 baud,
and setting EXTB will set 38400 baud.
The asyc driver supports both 16450 and 16550 UARTs and equivalents.
Files
The serial device nodes are provided as a shortcut to assist
applications in using the serial ports. They are
equivalent to opening a port with
open(S),
and then calling
ioctl(S)
with the TCGET and TCSET (see
termio(HW))
commands to set the node behavior.
The behavior of serial device nodes in both SCO OpenServer and
UnixWare are supported.
The ttyna and
ttynA nodes
behave identically to the SCO OpenServer nodes.
Software flow control (XON/XOFF) enabled.
Use when data integrity is not crucial,
for example, with mice.
The modem control line, Data Carrier Detect (DCD),
is required to be asserted
Terminal node. No flow control initially when opened.
Allows ports to be opened without a DCD line,
and allows
stty(C)
to be used on an unconnected port.
Used with 3-wire serial connections
(TD, RD and SG)
Usage
To activate additional ports
use the /sbin/dcu command;
see
dcu(ADM).
Apply the changes and exit dcu.
NOTE:
You need to reboot the system for the additional ports to work.
The order of entries in the DCU and the corresponding entries in the
asyc driver's space.c file must be in the same order for serial
consoles to work correctly.
Diagnostics
When using dcu to activate additional ports that share interrupts,
if you notice a message like
IRQ conflicts with an interrupt vector which cannot be shared...,
you need to change the ``ITYPE'' field to 3;
apply the change, exit dcu and reboot the system.
Notes
PCI Serial Support:
The asy and asyc drivers are configured by default to
support up to ten total serial ports.
The ports are named following the conventions described in the following
section.
The drivers support 16654 UARTS, as well as Digi Classicboard and
Connecttech Blue Heat PCI cards.
The device ordering is determined by searching entires in
pack.d/asyc/Space.cbefore any PCI devices are enumerated.
As a result, if the Space.c lists two serial ports
(com1, com2) and you only have one, but you have
a PCI serial card, port 01 will be treated as "broken" with the PCI
ports starting at 02.
To eliminate this, edit Space.c to match the actual hardware
configuration for non-PCI devices.
PCI devices honor the resmgr entries created or modified by
dcu(ADM).
Note that only scanned (i.e. not PCI) devices may be used for
kdb(ADM)
or console devices.
Serial Device Node Naming Conventions
The serial device nodes are provided as a shortcut to assist
applications in using the serial ports. They are
equivalent to opening a port with
open(S),
and then calling
ioctl(S)
with the TCGET and TCSET (see
termio(HW))
commands to set the node behavior.
The behavior of serial device nodes in both SCO OpenServer and
UnixWare are supported.
The ttyna and
ttynA nodes
behave identically to the SCO OpenServer nodes.
Equivalent device nodes
Behavior and use
/dev/term/0n
/dev/term/0ns
/dev/tty0ns
/dev/tty0n
Software flow control (XON/XOFF) enabled.
Use when data integrity is not crucial, for example, with mice.
The modem control line, Data Carrier Detect (DCD),
is required to be asserted
/dev/term/0nh
/dev/tty0nh
Hardware flow control (RTS/CTS) enabled.
DCD is required to be asserted
/dev/term/0nm
/dev/tty0nm
/dev/tty(n+1)A
Modem node. No flow control initially when opened.
DCD is required to be asserted
/dev/term/0nt
/dev/tty0nt
/dev/tty(n+1)a
Terminal node. No flow control initially when opened.
Allows ports to be opened without a DCD line.
Used with 3-wire serial connections
(TD, RD and SG)
and
UnixWare are supported.
The ttyna and
ttynA nodes
behave identically to the SCO OpenServer nodes.