Read/Write Memory (RAM)

Funtion Code	Name	Data Length	Core Purpose
03	Read/Write Memory (RAM) – Read Command	1~125 Registers	Read Command – Single or Multiple Holding Registers Used to read any desired configuration parameters.
06	Read/Write Memory (RAM) – Single Register Write Command	1 Register (16 bit)	Write Command – Single Int16 Parameter Used to write a simple single Int16 value, suitable for setting options, codes, or small-range integers. Example: Set A08 Pipe Material to PVC (code 2).
30	Read/Write Memory (RAM) – Double Register Write Command	2 Registers (32 bit)	Write Command – Float32 / Int32 (32-bit values) Used to write 32-bit values, such as floating-point numbers, supporting positive, negative, and fractional values approximately in the range 10⁻³⁸ to 10³⁸. Example: Set A18 Low Flow Cutoff to +5.5, or A23 Zero Offset to -0.08.
31	Read/Write Memory (RAM) – Four Register Write Command	4 Registers (64 bit)	Write Command – Int64 (64-bit values) Used to write 64-bit values, suitable for integer parameters exceeding the 32-bit range (~4.3 billion). Example: Set D11 Total Target (64-bit) or C04 Dosing Target (64-bit) to values exceeding the 32-bit limit.