The FSII BASEII has a 15-pin female DSUB with four GPO and two GPI (see FSII BASEII manual p. 14 for full pinout).
Currently only GPO 1 is in use and can be activated only with stage announce. The other GPIO are included for future use (firmware update).
GPO 1 can be activate by either pressing the SA key on the basestation or by assigning SA to a button on one or more beltpacks.
It can also be triggered if SA is assigned to a Group. Once assigned to a group, any endpoint with a key to the group can trigger the relay. Note that the audio output for stage announce is tied to the relay you cannot isolate the relay from the audio. if a user has a talk key to SA, they will trigger the relay and audio will be transmitted to the stage announce output (XLR) as well.
The relay will not trigger if SA is assigned to a Channel.
GPO 1 (Stage announce relay) uses pins 1,2,3 of the DSUB for COM,NC,NO respectively.