Communications using serial connections require several parameters on both ends of the connection match in order to successfully transfer information. The most critical information is the baud rate (bits per second), character size in bits, parity and its type (even or odd), and the number of bits used to mark the end of a character. Typically on UNIX and Linux systems you specify this information on a terminal (tty) using the command stty. This command lets you display the current settings of your terminal and lets you modify not only the characteristics previously mentioned, but others that also affect the amount of processing that is performed on data as it passes through the tty driver. Normally, there are procedures provided by the UNIX or Linux system to initially define the communication parameters on a tty without first needing to log on and adjust your interface.

To display the current communication parameter values for the console on a system, log on to the system through the console and enter the following command:

stty -a

tty interfaces are typically set to 9600 baud, 8-bit characters, no parity, and 1 stop bit. These settings are displayed by the stty report as

speed 9600 baud;  cs8;  -parenb;  -cstopb

Refer to your UNIX or Linux system documentation for stty and termio for a more detailed explanation of this command, its use, and its parameters.

If the settings of these parameters on your managed system console do not match the default values, you can either change the parameters for the console on the managed system, or configure Operations Sentinel to use values other than its defaults for that connection. See Section 5.4.3 “Configuring ANSI X3.64 Connections.”

If you elect to change the parameters on the console of the managed system, use the stty command or determine how your system defines the default values for the console port and change them appropriately.

To set the appropriate characteristics for the console on your system, use a command similar to the following:

stty 9600 -parenb cs8 -cstopb  </dev/console

For the command to be executed, you must have the appropriate permissions on the port /dev/console.

These changes may or may not be permanent, depending upon the actions your system takes when a user logs off and what happens when the system is rebooted. You should investigate the handling of serial communication parameters for your system to ensure that these changes are made permanent. Changing these parameters also requires similar changes to the terminal you may have attached to the console port through a signal splitter or switch box in order for you to continue to use that device as an interface to your system.

The alternative is to define the communications parameters for Operations Sentinel, so that when it connects to the serial port it will use values other than the default values. See Section 5.4.3 “Configuring ANSI X3.64 Connections.”