iFly GPS Forum

Setup: Grand Rapids Technologies Sport EFIS with a built-in WAAS GPS, a TruTrak Digiflight II w/o Vertical Steering, and a IFly 720. The 720 feeds the GPS signal to the GRT EFIS, through the serial interface, and can be selected to use the internal GRT GPS or the 720 signal to drive the GRT moving map and the autopilot. There is also a switch to drive the auto pilot directly from the 720 switching off the signal from the GRT. The autopilot can be used either to track a certain track or a flight plan from either source. The 720 is set at 9600 baud on the extended setting. Problem: Up to recently everything worked fine. Now when trying to drive the autopilot directly with the 720 in the track mode(control wheel steering mode), the autopilot indicates a track -35 degrees to the track indicated ion the 720 but continues to fly the plane in the 720 track. The operation in nav mode(flight plan) seems to work fine but also indicates the wrong track. Initially thinking something was wrong with my autopilot I tried driving it from the GRT and its GPS and the autopilot indicated the correct track. Then I switched the GRT to drive the autopilot with the 720 GPS signal and it indicated the track at 35 degrees less. Meanwhile the GRT moving map indicated a track of + 35 degrees. Through all of this the track on the 720 display remains correct. My assumption: Something is screwed up with the serial feed from the 720, but what? Can’t imagine it’s the recent software upgrade, no other changes with my equipment.

Walter, I set the NEMA output to normal, which I believe only sends the 2 basic sentences and still get the same problem. I did some additional simulation and noticed in a east west route the deviations appear to change when crossing the magnetic deviation lines. Discussed this with Ed in detail and he said he would pass this on. He also added me to the beta group to test if this is a bug in the new program. Vic Chewning

Ifly set for Magnetic North. Deviation in my area is 15.5W Attached is a photo of the panel flying in simulation near the 16 deg West deviation line. IFly is showing correct track of 000mag, AP shows track of 328 deg and EFIS track of 33 deg. Both are being fed from the IFly. ??? Vic