Apple Programming - FujiNetWIFI/fujinet-firmware GitHub Wiki
All commands to the Apple ][ FujiNet are issued via SmartPort.
In order to do so, you must first find the smartport card, and its dispatcher routine, and then you can issue a status command of $00 to get all devices. You can then iterate through them to find the device of an appropriate type (e.g. NETWORK or FUJI), and send commands to them.