Why the same Modbus registers can produce very different values
Modbus transports registers, not the meaning of the data. Two 16-bit registers may represent two independent numbers, a 32-bit integer, a Float32 value or a value that still needs scaling and an offset. The vendor register map and its exact data type therefore remain essential.
The most common field problem with 32-bit data is byte and word order. The same four bytes may need to be interpreted as ABCD, BADC, CDAB or DCBA. A wrong combination often produces a mathematically valid but physically meaningless number. Comparing all four interpretations and checking the result against the real device value is therefore useful.
A practical verification sequence
- 1. First confirm the register address and whether the documentation uses 0- or 1-based notation.
- 2. Then confirm the type: U16, I16, U32, I32 or Float32.
- 3. For 32-bit types, verify the correct byte/word order.
- 4. Finally apply the scale and offset specified by the vendor.
The converter is intended for diagnostics and learning. It does not guess the meaning of a register and does not replace device documentation.