EXTIO-232 is a CAT RS232 interface with band selection output (VOut connector). This interface is to be connected to the EXTIO DB9 connector of the FDM-DUO. It allows you to connect external equipment such as amplifiers or antenna controllers to the FDM-DUO. If the EXTIO connector of the FDM-DUO is used by the DUO-ART, the interface can be connected to the second EXTIO connector of the DUO-ART. The EXTIO-232 interface can also be used with the FDM-DUOr. Its firmware is upgradeable.