LON received frames begin with a preamble of variable length. The receiving algorithm does not check the preamble length, although a minimum of length of 4 bits is required for the receiving algorithm to consider the received preamble as valid.
As is the case with LON preamble transmission, two preamble patterns (ALL_ONE and ALL_ZERO) are allowed and can be configured through US_MAN.RX_PL. Figure 1 illustrates and defines the valid patterns.
Other preamble patterns are not supported.