dnp3.h File Reference

DNP3 (IEEE 1815) data-link frame codec (PC_ENABLE_DNP3) - zero-heap builder + CRC-validating parser for the SCADA / utility outstation link layer. More...

#include "protocore_config.h"

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Detailed Description

DNP3 (IEEE 1815) data-link frame codec (PC_ENABLE_DNP3) - zero-heap builder + CRC-validating parser for the SCADA / utility outstation link layer.

A DNP3 data-link frame:

0x05 0x64  LEN  CTRL  DEST(2,LE)  SRC(2,LE)  CRC(2)      // 10-octet header block
[<=16 user-data octets][CRC(2)] ...                      // data blocks, each CRC'd

• LEN counts CTRL + DEST + SRC + user data (the start word, LEN itself, and the CRCs are excluded), so LEN = 5 + user_data_len; min 5, max 255 (<= 250 user-data octets).
• Addresses are little-endian (LSB first). User data is carried in blocks of up to 16 octets, each followed by its own CRC; the header is its own CRC'd block.
• CRC is CRC-16/DNP (poly 0x3D65, init 0x0000, reflected in/out, final XOR 0xFFFF), transmitted low octet first.

This is the data-link layer (framing + CRC) plus the transport function (IEEE 1815 §8.2: segment header + fragment reassembly). The application layer (objects / function codes) is layered on the reassembled fragment.

Author

Douglas Quigg (dstroy0)

Date

2026

Definition in file dnp3.h.