IEC 60870-5-104

IEC 60870-5-104
Name	IEC 60870-5-104
Status	Published
Version	Edition 2 / Amendment
Organization	International Electrotechnical Commission
Domain	Electrical power system communications
First published	1996

IEC 60870-5-104 is a protocol specification for telecontrol in electrical power systems that adapts the IEC 60870-5 series to provide networked access over Internet Protocol and Transmission Control Protocol. It defines services, information object types, and mapping rules enabling supervisory control and data acquisition between control centers and substations across wide area networks, integrating with legacy SCADA infrastructures and contemporary Distributed Energy Resources.

Overview

IEC 60870-5-104 situates within the IEC 60870 family developed by the International Electrotechnical Commission's technical committees and is widely used in European electricity grid operations alongside standards such as IEC 61850 and IEC 62351. The profile maps application layer elements from the IEC 60870-5-101 serial standard onto TCP/IP to support remote supervision for Transmission system operator control centers, Distribution system operator facilities, and automated substation equipment. It defines interchange rules for interrogation, spontaneous reporting, command execution, and file transfer while allowing integration with asset management systems, Energy Management System platforms, and protection relays from vendors like ABB, Siemens, and Schneider Electric.

Protocol Architecture and Services

The architecture relies on an application layer specified by IEC 60870-5 and a transport/session mapping to TCP/IP and OSI model layers, enabling end-to-end connections between Master Station implementations and Remote Terminal Unit devices. Core services include fixed and variable length frame handling, single-command and double-command control operations, normalized group interrogation, counter interrogation, and time synchronization functions compatible with Coordinated Universal Time. The protocol supports balanced and unbalanced communication models, layered addressing for ASDU structures, and incorporates link-layer behaviour comparable to serial HDLC adaptations used by protocols like DNP3 and Modbus TCP.

Communication Mechanisms and Data Types

Information is organized into Application Service Data Units (ASDUs) with type identifiers for data semantics such as single-point information, double-point information, measured values (scaled and normalized), integrated totals, and event sequences. Data types align with common telecontrol semantics used by IEC 60870-5-101 while adding framing for packetized networks; typical ASDUs include cause-of-transmission qualifiers, sequence numbers, and object addressing that enable mapping to SCADA Historian records and IEC 61850 logical node attributes through gateway devices. Time-tagging uses CP56Time2a format for millisecond resolution to support event ordering in protection and control schemes similar to synchrophasor logging in Phasor Measurement Unit ecosystems.

Security and Reliability Considerations

IEC 60870-5-104 predates modern cyber security frameworks and thus requires supplemental measures from standards such as IEC 62351 and network practices like Virtual Private Network tunneling, IPsec, or Transport Layer Security gateways to provide confidentiality, integrity, and authentication across congested or hostile networks. Reliability is achieved through TCP connection management, sequence control, keep-alive mechanisms, and redundancy architectures including Hot Standby master station clustering and duplicate communication paths used in IEC 62439 media redundancy systems. Operational deployments must consider intrusion detection integrations with Security Information and Event Management tools and align with regulatory regimes like NERC CIP for critical infrastructure protection where applicable.

Implementations and Interoperability

Multiple commercial and open-source stacks implement the specification, enabling gateways between IEC 60870-5-104 and protocols like DNP3, IEC 61850, and OPC Unified Architecture. Interoperability testing is commonly performed in vendor-neutral interoperability workshops and conformance tests run by certification bodies and laboratories associated with the European Network of Transmission System Operators for Electricity and utility consortia. Implementations vary in support granularity for optional services, configurable timeouts, and ASDU subset selections, requiring careful profiling when integrating devices from suppliers such as SEL, GE Grid Solutions, Hitachi Energy, and specialist protocol gateway vendors.

Applications and Use Cases

IEC 60870-5-104 is applied in use cases including remote monitoring of substation automation equipment, telemetry for distributed generation plants like wind farm and solar photovoltaic sites, SCADA supervisory links for hydroelectric power station control, and automated distribution management systems coordinating smart grid functions. It enables telecontrol commands for switching, setpoint adjustments, and measurement reporting for asset condition monitoring in contexts ranging from urban distribution networks to cross-border transmission links managed by organizations such as ENTSO-E.

History and Standardization Process

The standard evolved from serial telecontrol requirements in the late 20th century and was formalized by the International Electrotechnical Commission to leverage packet-switched networks as IP technologies matured. Revisions incorporated clarifications for ASDU definitions, time-tagging, and mappings to ISO/OSI profiles, influenced by interoperability needs voiced by utilities, equipment manufacturers, and research institutions like Fraunhofer Society laboratories and university power system research groups. Coordination with related standards bodies and working groups ensured alignment with cybersecurity recommendations in IEC 62351 and facilitated practical deployment guidance distributed through regional standardization committees and industry consortia.

Category:Communication protocols