FUSION AUTOMATE TOOLS / INDUSTRIAL PROTOCOL TOOLS
Modbus Address Calculator
Convert register notation, offsets, hex and function codes. Fast, browser-local and free to use.
The first digit tells you the register family (0, 1, 3 or 4). Many devices and software use 1-based register notation (e.g. 40001), while the Modbus protocol itself uses a zero-based address (0) — so the device usually receives one less than what you type. Always check the device manual for its addressing convention.
A Holding Register is a 16-bit value you can both read and write — like a setpoint or speed reference.
Address information
- Register type
- Holding Register
- You type
- 40001
- Device understands
- Protocol 0
- On the wire (hex)
- 0x0000
- 1-based address
- 1
- 0-based address
- 0
- Function code
- FC03
- Data model
- 4x
- Request example
- 40001 ↔ 0
- ModScan shows
- 40001
In simple words: you write 40001 (human counting starts at 1), the device understands 0 (machines count from 0), and on the wire it travels as 0x0000 (hexadecimal). Three names, one register.