The output button is disabled when Ext trigger is selected as this configures the BNC connector as an input. The Output button determines whether the shared BNC connector is configured as an input or an output.
If the trigger option is not set to Ext, then the signal generator output may be used. The Output button enables the signal generator output. The output is active when the blue panel is illuminated.
The output waveform can be configured through the SignalGen option of the Tools menu.