Garmin MX20 - Stormscope Inputs; A.5 Stormscope Inputs

I/O Specifications
MX20 Installation Manual 560-1025-09 Rev E A-7
Figure A-3. Altitude Data Input
A.5 Stormscope Inputs
The WX-500 is the only Stormscope that the MX20 MFD interfaces with. It can be connected to RS-422
or RS-232.
RS-232
Connection TX J3-20
RX J3-8
RS-232_GND J2-5
Cable Twisted shielded triad 24 AWG wire
Voltage Logic 0 (space) Min: +5V, Max: +15V
Logic 1 (mark) Min: -15V, Max: -5V
Baud Rate 9600
Load Impedance 

RS-422
Connection TX+ J3-25, TX- J3-13
RX+ J3-24, RX- J3-12
GND CASE_GND
Cable Twisted shielded pair 22 AWG
Voltage Logic 0 (space) Min (A-B): +2V, Max (A-B): +6V
Logic 1 (mark) Min (A-B): -6V, Max (A-B): -2V
Baud Rate 9600
Load Impedance 
