Do MFDs require additional hardware when interfacing Mode S/TIS transponders for traffic display?
Yes, most modern Multi Function Displays (MFD) require additional interface modules to be installed into the internal structure of the actual display case. In particular, the KMD-540 (i.e. KMD-550/850) MFD requires the KAC-504 traffic module be installed into the display for interface to their KT-73 TIS transponder or any other compatible traffic system. The Garmin AT MX-20 also requires a hardware update for interface to their GTX-330 series TIS transponders or any other compatible traffic system.