IN is ADS-B IN, for weather and traffic. Do you have a Dynon ADS-B box (black, size of a paperback book, has its own antenna)?
If not, then you have one set up in your serial ports which is why you are getting the error. If yes, then it's wired wrong, doesn't have power, connected to the wrong port on SkyView, etc...
1 I have the ADS-B black Box
2 It is set up for serial port 3 on the PDF
3 It has ship's power on pin 1
4 It has a quality ground on pin 4
5 Pin 2 ADS-B is connected to Pin 8 on the PDF display 37 pin plug
6 Pin3 ADS-B is connected to pin 7 on the PDF display 37 pin plug
7 Antenna is connected and it is 4.5 feet from the same part number transponder antenna
8 Serial Port 3 Setup
Serial in Device Dynon ADSB-470
Nav Source Display Name (not set)
In/Out Baud Rate 115200
Serial out Device Dynon ADSB-470
TX Counter 22746
RX Counter 0
All other lines = 0
9 I did notice that there is a connection between the ADSB pin 3 to Transponder (Skyview 261) pin 3 through a 1.12K resistor. This connection also goes to my SL40 pin 10 and my Garmin 396 data out pin.
What do I check or do now?