Changing the firmware on an Actisense EMU-1 is a straight forward process, which only requires a PC to run the freely downloadable Actisense Toolkit, and an Actisense NGT-1 to communicate between the NMEA 2000 bus and the PC.

For a step by step guide on upgrading / downgrading the EMU-1, follow this link: https://www.actisense.com/knowledge-base/nmea-2000/emu-1/how-to-upgrade-downgrade-emu-1-firmware/