A simple Windows program called File Format Convert can be started from the Windows Start menu: Campbell Scientific | LoggerNet | Utilities | File Format Convert.
There is also a console program, toa_to_tob1.exe, that is included in the LoggerNet installation directory: C:\Program Files (x86)\Campbellsci\LoggerNet\toa_to_tob1.exe
This program must be started from a console window (command prompt), and it expects two arguments: an input file name (the first one) and an output file name (the second one).