The Modbus Application Protocol Specification is the primary reference for engineers implementing or reviewing Modbus client and server behaviour. It explains the protocol data unit, function-code structure, addressable data models and exception responses used across serial and TCP implementations.
Use this reference when validating request construction, decoding device responses, checking interoperability or documenting a Modbus interface.
This reference is maintained by Modbus Organization. Use the official source for the latest revision and licence terms.
