ace - Serial communications interface
controller ace0 at * slot ? vector aceintr
The ace serial line controller provides a serial communications
interface on DEC 2000, AlphaStation, and
AlphaServer platforms. The serial communications ports
that are controlled by ace adhere to the RS-232 standard
and can operate at rates from 50 to 115200 baud (see
tty(7)). These communications ports support serial-line
printers, modems, and terminals.
In alternate console configurations (that is, no graphics
head), the terminal to be the system console must be connected
to the port that is mapped to /dev/tty00. (See
ports(7) for information about mapping AlphaStation and
AlphaServer port labels to device pathnames.) Currently,
some processors that use the ace driver limit the serial
console port to 9600 baud, 8-bit, no parity and no modem
support. However, some processor consoles do support baud
rates other than 9600 baud and allow the use of modems as
console devices. Consult your hardware documentation to
determine the type of console support your system provides.
The driver for the ace interface supports hardware flow
control using the Request to Send (RTS) and Clear to Send
(CTS) signals. When hardware flow control is enabled, the
flow of input data is controlled by the RTS signal and the
flow of output data is controlled by the CTS signal. If
the CTS signal is off, the driver suspends output to that
line until the CTS lead is reasserted. Likewise the
driver turns off the RTS lead to tell the device connected
to the line to stop sending data as a result of congestion
on the host side. When the condition clears, the driver
turns on the RTS lead to tell the device to resume sending
data.
The DCD (carrier detect) timer value defaults to 2 seconds.
This value may be changed if your modem hardware
requires a different value. the change can be made in the
/etc/sysconfigtab file as follows:
ace: dcd_timer=n
where n is the time interval in seconds, and can be set to
0 (no timeout), 1, or 2 seconds. Alternatively, you can
use the sysconfig command to set the same time interval
option as follows:
# sysconfig -r ace dcd_timer=[n]
If you use the sysconfig command, the value will not be
preserved when the system is rebooted. To preserve the
setting, put the entry in the /etc/sysconfigtab file
If you are using the alternate system console to perform
kernel debugging, you must change the kdebug entry in the
/etc/remote file to use /dev/tty01; when the kernel is
running in debugging mode, no other application can use
the port. See Kernel Debugging for information on setting
up your system for kernel debugging.
Unless alternative specifications are stated in your system
hardware documentation, data communications equipment
attached to the console serial port in alternate console
configurations must be set to 9600 baud, 8-bits, no parity.
If a serial console is being used, /dev/tty00 cannot
be opened by another process. The ace driver enforces
this restriction.
Baud rates greater than 38400 are not supported on the two
primary serial ports on the DEC 2000 system. However, if
you use an ISA serial or modem card that is capable of
communicating at the higher rates, the higher rates are
supported.
console terminal local terminal local terminal
MAKEDEV(8), console(7), devio(7), modem(7), ports(7),
tty(7)
Kernel Debugging
System Administration
ace(7)
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