Failsafe should be set immediately after you finish building your miniquad. Failsafe will determine what stick position will be used when your receiver stops receiving information from the transmitter, or when the connection is lost. Setting up frsky failsafe is very straight forward and should take less than a second.
X4R SB comes with a stock firmware allowing s.bus only. We will flash X4R SB with a newer firmware which will allow us to use it either in s.bus, or PPM. On top of that, channels 2 and 3 on PPM mode will act as CH9 and CH10.