What is byte and word ordering?
The Modbus specification doesn’t define exactly how the data is stored in the registers. Therefore, some manufacturers implemented modbus in their equipment to store and transmit the higher byte first followed by the lower byte. (AE before 41). Alternatively, others store and transmit the lower byte first (41 before AE). Similarly, when registers are combined to represent 32-bit data types, Some devices store the higher 16 bits (high word) in the first register and the remaining low word in the second (AE41 before 5652) while others do the opposite (5652 before AE41) It doesn’t matter which order the bytes or words are sent in, as long as the receiving device knows which way to expect it. For example, if the number 29,235,175,522 was to be sent as a 32 bit unsigned integer, it could be arranged any of these four ways.
