So I downloaded the Bossa & bossac off http://www.shumatech.com/web/products/bossa
I scanned the available ports with these are the options
bossa> scan Checking port cu.Bluetooth-Incoming-Port... Checking port cu.usbmodem1421...
So then I just want to check if bossac can connect with the device.
bossac -p cu.usbmodem1421 -i No device found on cu.usbmodem1421
I'm on os x btw and the Arduino IDE can write to the Due fine.