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Data ModelModbus Term

Register Address

The numeric location of a register within its register table.

Definition

A register address identifies the position of a register within its type table (coil, discrete input, input, or holding). Addresses are 0-based in the protocol (0–65535) but are often shown as 1-based 5-digit numbers in datasheets (40001, 30002, etc.). The protocol address in a request is always 0-based — you subtract 1 from the datasheet number when building requests.

Quick Facts

Protocol (0-based)0x0000–0xFFFF (0–65535)
Holding 1-based40001 = address 0
Input 1-based30001 = address 0

Related Terms

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ModPackQT Modbus Glossary · Updated 2026