Detailed Description

IEC 60870-5-101 / -104 telecontrol (SCADA) codec (PC_ENABLE_IEC60870).

The IEC 60870-5 utility-SCADA protocol in its two common transports:

-104 over TCP: the APCI (68 LEN + 4 control octets) in its I / S / U formats, carrying an ASDU. I-format transfers numbered information (send/receive sequence numbers); S-format acknowledges; U-format does STARTDT / STOPDT / TESTFR.
-101 over serial: the FT1.2 link frames - fixed length (10 C A CS 16) and variable length (68 L L 68 C A <ASDU> CS 16, 8-bit sum checksum), with a 1-octet link address.
The shared ASDU header (type id, variable structure qualifier, cause of transmission, common address) and the 3-octet Information Object Address used by both.

Typed information objects for the common type ids are provided: single-point (M_SP_NA_1), double-point (M_DP_NA_1), short-float measured value (M_ME_NC_1), single command (C_SC_NA_1), and double command (C_DC_NA_1), each an IOA + value + quality / qualifier descriptor. The remaining per-type-id elements are the application's; this is the framing + ASDU layer with named type-id / COT constants for the common ones. Pure and host-tested. Bridge an RTU / outstation onto Wi-Fi: run -104 over the shipped TCP stack, or -101 over a UART through an RS-232/485 transceiver.

Author: Douglas Quigg (dstroy0)

Date: 2026

Definition in file iec60870.h.