One BSG IBUS has 12 buttons.
If you need more than 12 buttons’ IBUS output for car radio(or original equipment) though BSGd, you can use another BSG index as slave BSG
IBUS.
The IBUS messages of the slave BSG IBUS are outputed through BSGd on the CPJexc.
If this BSG module is the master BSG module, choose “Master”.
If this BSG module is the extension of the other BSG, choose the master BSG index of this BSG module at Master BSG Index.

For example,
If Mater BSG Index is 1, this BSG index works as a part of the BSG index 1.
Even though both BSG index 1 and 2 are all Master, IBUS message is sent normally.
The reason of putting Mater BSG Index is to share the Idle Message of Master BSG index.