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Errors & ExceptionsModbus Term

Exception 02 — Illegal Data Address

The register address or address range does not exist on the slave.

Definition

Exception code 02 (Illegal Data Address) means the starting address or the address range (start + quantity) falls outside the slave's implemented register space. This is one of the most common Modbus errors. Double-check the starting address is 0-based and that start + count does not exceed the valid range.

Quick Facts

Code hex0x02
CauseAddress out of range or datasheet address not adjusted to 0-based
FixSubtract 1 from 1-based datasheet addresses

Related Terms

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ModPackQT Modbus Glossary · Updated 2026