RS-485 Communication Features
Modbus-RTU Protocol
7.3.2.1 Function Code and Protocol (unit: byte)
In the following section, station ID is the value set at CM.01 (Int485 St ID), and starting
address is the communication address. (starting address size is in bytes). For more
information about communication addresses, refer to 7.4 Compatible Common Area
Parameter on page 289.
Function Code #03: Read Holding Register
Function Code #04: Read Input Register