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Fixing incomprehensible serial port traffic following an update

Wrench_Bld.pngThis article covers what to do if a Tesira serial port is not responding to the expected Baud rate and outputting garbled text.  


New Tesira installations or existing installations with firmware upgrades

After a firmware update, the serial port(s) on a Tesira box may not reinitialize properly and get set to a bogus baud rate. This results in no RS-232 connectivity and garbage responses when trying to communicate with the Tesira over serial. Customers might experience a formerly healthy Tesira system with serial (RS-232) control no longer functioning after a firmware update.


Change the Port Settings

This issue can be fixed in three steps.

  1. Go into the Port Settings within Device Maintenance. 



  1. Change the baud rate to a different value than desired (doesn't matter what, just make it different) and hit OK to save.



  1. Once saved, go back into the Port Settings, adjust back to the desired baud rate, and hit OK to save.


Verify the settings with a telnet client and test command

Once these settings are complete, test with the existing control system or simply connect with a serial client. Once confirmed operational, a hard reboot of the Tesira is recommended to lock in the serial settings.


Further reading - for testing, analysis, and a simulation tool for serial communication protocols - a freely available telnet/ssh client used in this tech note