Finished wiring my serial communications as follows
Com1 - AFS Pilot
Com2 - Aviation/Icarus (300XL source, GMA327 destination)
Com3 - SL-30
Com4 - Airinc

Two items not understood.

1) The clock never displays time (timer works) this was tested with only Com2 connected and the 300XL gps locked

2) The SL-30 NAV is displayed and controlled by the EFIS but the COM can only be displayed. Xfer etc only works on the NAV side of the radio