Method for encoded diagnostics in a functional safety system

A method comprising, at a first controller in a system:

• storing a first set of codewords comprising:
• a first functional codeword representing a functional timeout state of a second controller in the system;
• and
• a first fault codeword representing a fault timeout state of the second controller;
• in response to receiving a first message from the second controller within a first time quantum during a first time period, storing the first functional codeword in a first memory;
• and
• in response to a match between contents of the first memory and the first functional codeword during a second time period succeeding the first time period, outputting a second message comprising a second functional codeword representing a functional state of the system.

A method comprising, at a first controller:

• storing a set of codewords comprising:
• a first functional codeword representing a functional timeout state of a second controller in the system;
• and
• a first fault codeword representing a fault timeout state of the second controller;
• in response to receiving a first message from the second controller during a first time period, storing the first functional codeword in a memory;
• and
• in response to a difference between contents of the memory and each codeword in the set of codewords during a second time period, outputting a second message comprising a second fault codeword representing a fault state of the system.