NASA Protocol

General
The indoor and outdoor unit of the EHS heat pump communicate via a protocol called "NASA".

Physical layer
The data is transmitted via a RS-485 link with 9600 baud, even parity and one stop bit.

Protocol details
The indoor and outdoor unit both regularly transmit their current status and sensor readings via so called "packets". Each packet contains metadata, like the sender and receiver address as well as the actual payload data, which is structured into "messages". Every packet can contain one or more messages.

Packet structure
Thank you to lanwin, who implemented esphome_samsung_ac and was the first to understand the structure of the NASA Messages.