I’m getting a red GPS integrity message on the AFS 3500s EFIS and map page. I’m getting the same thing on the AFS 3400s EM. The 3500s and 3400s are connected together with an Ethernet cable. The other units in the panel are a Garmin GNC 300 XL GPS COMM, Garmin GMA 347 Audio Panel, Garmin GTX 327 Transponder, AFS Arinc, and an AFS Autopilot. The GPS COMM is receiving several satellites and it says it is ready for navigation. So the GPS COMM and EFIS are not communicating. The GNC 300 XL GPS COMM does have a RS-232 interface. All of the electronics are connected together with cables made by Approach Fast Stack, plugged into a Pro-X Hub. I feel strongly that the Wiring/ cabling is correct. On the EFIS and EM about page, they both show the latest software S8.8.25-MV16[/U] Arinc 4.0. I’ve tried different settings in serial port #1 and it did not help. So what do I do to get the GPS COMM to communicate with the EFIS? Thanks

These are the settings under EFIS > Navigation for both the 3500s and 3400s, CRS/ GNAV 1, BRG/ GNAV 1, CDI/ AUTO

Under Admin settings
EFIS 3500s EM 3400s
5 Serial Port #1 Function = AVTN/AVTN Function = Disabled
6 Serial Port #2 Function = TRFC/ICARUS Function = Disabled
7 Serial Port #3 Function = DISABLED Function = Disabled
8 Serial Port #4 Function = ARINC Function = VPX

#9 Autopilot Type Trutrack Autopilot Type = Trutract
#10 GPS/NAV1 Data Source Serial Port #4 Remote Arinc
#11 GPS/Nav2 Data Soucse None None
#12 GPS/Nav3 Data Source None None