Revision A9 21
GRT Avionics Mini-X Installation, Setup & User Manual
2.8 General Serial Port Wiring Information
The Mini’s RS-232 serial ports can be used to connect the Mini to a variety of interfacing equipment.
In systems using a larger GRT display unit as the primary EFIS, the Mini-X serial ports will most
likely be used to connect to the GRT Autopilot servos and the primary GRT EFIS screen for limited
data sharing, including flight plans, screen dimming, and altimeter settings. Radios with a serial
interface can be tuned from the Mini’s Waypoint Details frequency list.
Serial Port Basics-
All serial ports have two parts: “IN” (Receive) and “OUT” (Transmit). Data packets
are transmitted or received at a certain rate, called the
baud rate
. Every device that connects to a
serial port has a published baud rate, which must be entered into the Serial Port Rate setting for
the device to communicate with the Mini.
Some devices use both the IN and the OUT channel on a serial port, and some use either IN or
OUT. If two devices share one serial port, the baud rate of both devices must be the same. For
example, the Mini can take GPS position from a handheld GPS, but it can’t talk back to the GPS;
therefore, the GPS only requires the IN half of the serial port. The Mini transmits encoder data to
a transponder, but cannot receive data from the transponder. The GPS and transponder can share
the same serial port IF both devices use the same baud rate.
Choices available for the Mini serial interface include:
Serial Equipment
Notes
Off
No connection
NMEA0183 GPS1/Global
Positioning
Primary external GPS, such as a GRT GPS module.
Most handheld GPS units use this data format.
GPS1 Aviation/MapCom
Garmin IFR nav unit (GNS430, etc)
NMEA0183 GPS2/Global
Positioning
Secondary External GPS
GPS2 Aviation/MapCom
Secondary Garmin IFR nav unit
SL30-1
Primary nav/com using Garmin SL30 protocol
SL30-2
Secondary nav/com using Garmin SL30 protocol
SL40-1
Primary com using Garmin SL40 protocol
SL40-2
Secondary com using Garmin SL40 protocol
Display-Unit Link
Connection to other GRT display units
SL70/STX165
Serial transponder encoder data
GRT Autopilot Servo
Splice serial wires to feed to both servos.
TT22
Trig TT22 or TT21 remote transponder using the GRT
Serial Adapter. Not required if the TT22 is wired to
the dedicated TT22 port instead. See Section 2.7 for
more information.
