MB_PDU_SIZE_MAX macro

Constants which defines the format of a modbus frame. The example is shown for a Modbus RTU/ASCII frame. Note that the Modbus PDU is not dependent on the underlying transport. +-----------+---------------+----------------------------+-------------+ | Address | Function Code | Data | CRC/LRC | +-----------+---------------+----------------------------+-------------+ | | | | (2) (3/2') (3') (4) (1) ... MB_SER_PDU_SIZE_MAX = 256 (2) ... MB_SER_PDU_ADDR_OFF = 0 (3) ... MB_SER_PDU_PDU_OFF = 1 (4) ... MB_SER_PDU_SIZE_CRC = 2 (1') ... MB_PDU_SIZE_MAX = 253 (2') ... MB_PDU_FUNC_OFF = 0 (3') ... MB_PDU_DATA_OFF = 1 Maximum size of a PDU.