The connections of interest are DIN 5 for data on the right and DB9 for CAT on the left:
DIN 5 pinout is:
So the data cable pinout would be:
DIN 5 Male 1 (DATA IN) → 3.5mm TRRS ring 1 (RIG_AFIN)
DIN 5 Male 2 (GND) → 3.5mm TRRS sleeve (GND)
DIN 5 Male 3 (PTT) → 3.5mm TRRS ring 2 (PTT)
DIN 5 Male 4 (DATA OUT) → 3.5mm TRRS tip (RIG_AFOUT)
DIN 5 Male 5 (BUSY) → NC
Because FT-920’s DB9 connector is female, Digirig’s standard RS-232 cable with female connector will not work with it (nothing against this, it just doesn’t work with electronics). This calls for a custom DB9 male serial cable for Digirig:
DB9 pin 2 (SERIAL OUT) → 3.5mm TRRS ring 1 (RIG_TXD)
DB9 pin 3 (SERIAL IN) → 3.5mm TRRS tip (RIG_RXD)
DB9 pin 5 (GND) → 3.5mm TRRS sleeve (GND)