EXFO FTB-2 - Manual (Page 158)

Managing Data
148 FTB-2 and FTB-2 Pro
Using the USB to RS-232 Adapter
Using the USB to RS-232 Adapter
If you want to transfer data between your unit and a device that is only
equipped with RS-232 (serial) ports, you have to use a USB/RS-232 adapter
(sold by EXFO).
Once the adapter has been detected, the unit assigns it a COM port number
(for some adapters, values do not begin at COM 1). This COM port number
is kept in memory even when you turn the unit off. This means that next
time you connect the same adapter to any of the USB ports, the unit will
recognize the adapter and identify it with the saved COM port number.
The communication between your unit and the device is established using
the PuTTY application.