The IFD is providing all of the deviation data to the Aspen via ARINC 429 (digital) and the Aspen then sends that digital data to the ACU, which processes the information and outputs the analog equivalent to the autopilot. The way the Aspen does this is dependent upon what mode is selected on the Aspen. For insta…
Intro to IFD Interfaces with EFIS Systems IFD Interfaced with Aspen EFD1000 Troubleshooting IFD Interfaces with EFIS Systems Main ARINC429 Config Page VOR/ILS 429 Configuration Page