Garmin G500 Manual page 36

When GPSS is selected on the PFD, GPSS is annunciated in the lower left
portion of the PFD. The GPSS mode annunciation depends on the location of
the NAV STATUS information, as shown below.
NAV STATUS STYLE 1 NAV STATUS STYLE 2
NOTE
GPSS mode is selectable from PFD 2, but GPSS is not
annunciated on PFD 2. The GPSS commands to the autopilot
are based on the GPS source displayed on PFD 1.
When GPSS is selected on the PFD, GPSS turn commands are converted into a
heading error signal to the autopilot. When the autopilot is operated in HDG
mode, the autopilot will fly the turn commands from the GPS navigator selected
on PFD 1.
If the GPSS data is invalid (for example, if there is no active GPS leg) or the
selected HSI source on PFD 1 is not GPS, the annunciated GPSS text will be
yellow and a zero turn command will be sent to the autopilot.
4.6.5 Roll Steering capable autopilots
If the autopilot is already designed to receive Roll Steering information, the data
is transmitted via a digital communications bus from the G500 to the autopilot.
The G500 receives this data from the GPS. In dual GPS installations, the G500
sends Roll Steering information for the GPS which is currently selected for use
via the PFD 1-2 button.
AFMS, GARMIN G500 PFD/MFD SYSTEM 190-01102-01 Rev. 9
FAA APPROVED Page 36 of 40