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Function CodesModbus Term

FC16 — Write Multiple Registers

Write a block of 16-bit values to consecutive holding registers.

Definition

Function Code 16 writes values to one or more consecutive holding registers. It is the standard way to write multi-register data types like 32-bit floats (2 registers), 32-bit integers (2 registers), or to set multiple parameters atomically. The response returns the starting address and quantity of registers written.

Quick Facts

FC hex0x10
Max registers123 per request
Common useWrite FLOAT32, INT32, setpoints

Example

Write 200.0 as FLOAT32 (AB-CD order) to registers 10–11 on slave 1:
01 10 00 0A 00 02 04 43 48 00 00 CF 4B
               │  │  ├──────────┤
               │  │  Data (4 bytes = FLOAT32 200.0)
               │  Byte count (4)
               2 registers

Related Terms

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ModPackQT Modbus Glossary · Updated 2026