Garbage Printing on the Attached Terminal Printer or Modem


Garbage characters printing on an attached terminal, printer or modem session.


The main cause of this behavior is a baud rate mis-match. The port is configured for a different baud rate than the attached device.

In the case with modems this is usually an indication that the DTE baud rate has not been set.


Make sure the port is configured for the same baud rate as the attached device. If enabling the port for login, verify that the appropriate gettydefs value is being used (i.e. m = 9600, n=19200 etc...). If the port is not enabled, check the port baud rate setting using ditty from the UNIX root prompt: 

# ditty -a (port_name)

To set the port baud rate to be "sticky" using ditty:

# cat < (port_name) > /dev/null &
# ditty 19200 (port_name)

This can be placed in a start-up script to make the settings permanent upon a system reboot.

For modems, configure the DTE baud rate appropriately.

Last updated: May 15, 2019

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