PLC Simulator
Modbus function reference

Modbus Function Code 16 — Write Multiple Registers

Write a contiguous block of 16-bit registers

16
Load in Modbus sandbox

Data model

Holding registers (4xxxx reference family)

Access

Write a contiguous block of 16-bit registers

Protocol quantity

1–123 registers

Worked example

Read the PDU field by field.

Write two registers beginning at protocol address 1 with values 10 and 258.

Typical use: Writing multi-register parameters or blocks when atomic grouping is supported and documented.

Example protocol data units

Request PDU

10 00 01 00 02 04 00 0A 01 02

Normal response PDU

10 00 01 00 02

PDU examples omit the Modbus TCP MBAP header and the Modbus RTU unit-address/CRC envelope. Multi-byte values are shown in network byte order.

Common implementation mistakes

  • Using 125 as the write limit instead of 123
  • Splitting a 32-bit value with the wrong word order
  • Assuming a multi-register parameter can be partially written safely

Run the reference

Turn a protocol table into evidence.

Compose the request publicly, then use Pro for advanced graded exceptions, saved fixtures, complete history and project sharing.

Open sandbox