The Modbus RTU Function
04 is used to Read Input Registers, (3x register references), in a
Modbus Slave device. Registers are addressed starting at zero: meaning registers 1–10 are addressed as
Modbus Function 04 also includes the quantity of registers to read from the Modbus slave device.
See the example command below that reads one register, 30010 from Modbus Slave address 01.
Measure Seven Thermocouples with a DGH D6300!
Using the Modbus RTU Protocol