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Data ModelModbus Term

Coil (0x Registers)

A 1-bit read/write digital output — address range 00001–09999.

Definition

Coils represent digital outputs that a master can read and write. Physically they often control relays, solenoids, or indicator lamps. In the register address space they occupy the 0x range (00001–09999 in 1-based notation, 0–9998 in 0-based). Each coil is a single bit — either ON (1) or OFF (0).

Quick Facts

Bit size1 bit
0-based range0–65535
1-based range00001–09999
Read withFC01
Write withFC05 (single), FC15 (multiple)

Related Terms

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ModPackQT Modbus Glossary · Updated 2026