12-05-2003
Please click on the rules link at the bottom of the page. I have deleted your other thread.
You're not going to be able to do what you want. Use the command "man termios" to see what is available from the terminal driver. Use our search function to searc this forum to see some examples of termios in use.
In you have the hardware, you can use modem control signals, but the driver does it on your behalf. For an incoming line, a open() call raises DTR which signals the modem that it may auto-answer a call. When it does, it will raise DSR which causes the open to complete. If DSR drops, a hup signal is generated. A very clever program might be able to use all of this to "read" the state of the DSR signal. But open() is an expensive system call and the bandwidth would be low.
Some unix systems (maybe most? or all?) you can use CTS for hardware flow control of output, and RTS for hardware flow control of input. There is no hope for RTS, but a clever program might be able to determine the state of CTS by seeing if a non-blocking write() succeeds. But DSR would need to be high.
You might be able to have a simple switch send a break character. Anyone who uses a Sun with a terminal console knows how easy that is. You can arrange for a break character to send an INT signal to the program.
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LEARN ABOUT HPUX
pmux_stty
pmux_stty(1) General Commands Manual pmux_stty(1)
NAME
- set the options for a port on the HP AD278A/AD279A PCI Mux card.
SYNOPSIS
options]
DESCRIPTION
The command options are used to turn on and off a number of special flags. These flags are used to control driver I/O processing on a PCI
Multiplexer port. These commands are enhancements to the standard commands, and affects the operation of the port.
Many of the output modes are implemented in the AD278A/AD279A PCI Mux hardware. This allows greater throughput with less CPU processing
overhead than other serial I/O devices. There are some features which are still handled by the line discipline and the use of these fea-
tures results in traditional CPU overheads and throughput.
If flag is not enabled then maximum output performance is achieved. Even if flag is enabled, the settings are handled in the hardware and
maximum output performance will still be maintained. Following are the settings that are handled in hardware:
The use of other settings results in additional software overhead on output characters.
Use of "raw" mode on input also maximizes throughput and reduces CPU processing overheads. However, even in raw mode some and settings
require line discipline intervention. Applications that want maximum throughput and/or minimal CPU overhead must avoid the following set-
tings:
The line discipline also supports the "block mode" feature. When a device is in "block mode", software overhead is introduced to handle
the device protocol and the benefits of the AD278A/AD279A HP PCI Mux hardware are also mitigated.
The commands are usually enabled at the terminal using the format:
pmux_stty [+(-) option]
or, they may be entered from the console, and redirected to the port in which they are to take effect. For example,
pmux_stty [+(-) option] < /dev/tty2a1
See below for the new naming conventions used for HP AD278A/AD279A PCI Mux ports.
DISPLAY OPTIONS
To see the complete list of available options and syntax for the command, enter without any options. The options are:
Report the current settings of the pmux_stty options.
Display the HP AD278A/AD279A PCI Mux hardware configuration, including
the logical card number, ID, slot, and type of the cards that are installed and configured.
Use pmux_stty dtr 1 to force the DTR control signal high, regardless of the application.
Ignore (do not ignore) the
option, which permits any character to act as an XON character for resuming output.
A number of applications enable the feature in the standard profile. This destroys the integrity of software flow
control because any user type ahead is erroneously interpreted as an XON after the terminal sends an XOFF. The
command is provided to correct the most common application-related problems experienced when running terminals at
high speed.
NOTE: is transparent to users. It should always be set for terminal speeds above 9600bps when hardware flow con-
trol is not used.
Ignore (do not ignore) the
option, which is used by some applications to disable XON/XOFF software flow control. Setting this option forces
the driver to apply XON/XOFF flow control to the port, regardless of whether or not the application has set
Perform physical loopback test. Invoke the loopback test with
loopback plug connected to a port.
e.g.,
Display the current status of the RS-232 modem control
signals (RTS, CTS, DSR, DCD, DTR, and RI) for a port.
Restart stopped output exactly as if an XON character was received.
Forces a port to honor and pass (not pass) XON/XOFF software flow
control, until the port is closed, or the option is disabled. This is useful for applications that need to see
XON/XOFF characters.
NAMING CONVENTION
HP AD278A/AD279A PCI Mux ports use the following syntax for naming device files:
where categoties are:
tty = direct connect
ttyd = modem dial-in
cul = modem dial-out
cua = modem dial-out with automatic caller
refers to a device instance number
refers to a port module whose valid range is 'a' to 'd'
and
refers to a port number whose valid range is 1 to 16.
SEE ALSO
stty(1), termio(7), modem(7).
pmux_stty(1)