Message types
OPN - Open, modifies the address table (RAM 256x1) of every node, when passing through, RAM[source_adr] = 1
CLS - Close, modifies the address table of every node, when passing through, RAM[source_adr] = 0
LWR - Local Write, packet header, exchange of data between two nodes
GWR - Global Write, packet header of a broadcast message
PLE - Packet Length in multiples of 4 bytes, must follow LWR or GWR