The selection in the dropdown list control on TES' "Configuration" tab cannot be changed. Only the options "Select" and "OBSON" are available when the list drops down, and only the latter can be selected. I also note that no means is provided to select the desired Observation Rx channel (e.g., Sniffer A, B, or C).
Additionally, the "Rx Chnl" dropdown list also has an unselectable "Select" option, and the "RXOFF" option (visible in the illustration of this tab in UG-992) is not present in the list.
I am running 64-bit Windows 7 Professional SP1 and TES v2.0.62.