คู่มือ Modbus

The manual says register 40010, but the request needs offset 9. Follow a complete Modbus read to check address notation, FC03, and decimal versus hex input.

Calculate a Modbus CRC-16 for an RTU read request, compare 0BC4 with C4 0B, and check a captured frame without adding a second checksum.

Convert 3F800000 to a float and see why 3.14 does not round-trip exactly in FLOAT32. Includes byte-order examples for values stored in two Modbus registers.

Compare Modbus RTU, ASCII and TCP framing, checksums, serial timing and gateway behavior, with implementation examples and deployment considerations.

Learn how Modbus ASCII encodes bytes as hexadecimal characters, frames messages with a colon and CRLF, and checks them with an LRC.

Understand the Modbus TCP MBAP header, transaction IDs, register requests and exceptions, and how TCP framing differs from Modbus RTU.

Learn the Modbus RTU frame format, CRC-16, register addresses and byte order, with examples for reading registers and checking device responses.