# IEC 60870-5 — Telecontrol transmission protocols (SCADA) > IEC 60870-5 is the European family of telecontrol protocols that carry SCADA data between control centres and substations. IEC 60870-5-101 runs over serial links; IEC 60870-5-104 carries the same application layer over TCP/IP. It is the power-grid counterpart to DNP3 (IEEE 1815), and it gains security from the IEC 62351 series. - Source : https://industryhub.site/en/standards/iec-60870 - Body : IEC - Family : Grid Communication - Status : current - First published : 1990 - Latest revision : Part-specific (60870-5-104:2006) - Edition : Multi-part - Next revision : Active maintenance - Access : Paid (IEC webstore) - Language : English ## Document structure - **IEC 60870-5-101** — Basic telecontrol tasks (serial) : The companion standard for basic telecontrol over serial links between a control centre and an outstation (RTU). Defines the application data — measurements, status, commands — independent of the transport. - **IEC 60870-5-104** — Network access (TCP/IP) : Carries the same 101 application layer over standard TCP/IP transport. The protocol of choice for modern wide-area SCADA, often shortened to IEC 104. - **IEC 60870-5-103** — Protection equipment interface : A companion standard for the informative interface to protection relays in substations. - **IEC 60870-6 (TASE.2 / ICCP)** — Control-centre to control-centre : The inter-control-centre communications protocol (ICCP), for data exchange between utility control centres. ## Key concepts - **Telecontrol** : Monitoring and commanding remote equipment — substations, RTUs, feeders — from a central SCADA system over a communications link. 60870-5 standardises how that conversation is encoded. - **-101 serial vs -104 TCP/IP** : Both carry the same information; only the transport differs. 60870-5-101 uses serial (RS-232/485, FSK); 60870-5-104 wraps the identical application layer in TCP/IP, enabling routed wide-area networks. - **ASDU and information objects** : Data travels as Application Service Data Units carrying typed information objects — measured values, single/double points, commands — each with a cause of transmission and an address. This typing is what makes the protocol interoperable. - **DNP3 (IEEE 1815), the cousin** : DNP3 shares a common origin with 60870-5 and does the same job. 60870-5-101/104 dominate in Europe; DNP3 dominates in North America. Many RTUs and gateways speak both. - **No native security — IEC 62351** : 60870-5-104 was specified without built-in security. Authentication and encryption are added by the IEC 62351 series, now essential given the protocol's exposure on routed networks. - **Not a replacement for IEC 61850** : 60870-5 is a wide-area telecontrol protocol between centres and stations; IEC 61850 is the high-speed model inside the substation. They coexist — a station runs 61850 internally and reports upward over 60870-5-104. ## Talking to substations over distance A grid control centre may oversee hundreds of substations spread across a region. It needs to read their measurements, see their status and send commands — reliably, over whatever link is available. **IEC 60870-5** is the European family of **telecontrol** protocols built for exactly that conversation, and in modern networks its member **IEC 60870-5-104** is everywhere. ## -101 and -104 — the same data, two transports The clever part of the family is the split between *what* is sent and *how*. **IEC 60870-5-101** defines the application data — measured values, single and double points, commands — as typed **information objects** carried in **ASDUs**, each with an address and a cause of transmission. That data definition is transport-independent. **60870-5-101** carries it over serial links; **60870-5-104** wraps the identical application layer in **TCP/IP**, so the same SCADA logic runs over routed wide-area networks. Inside substations, **60870-5-103** interfaces to protection relays, and **IEC 60870-6 (ICCP/TASE.2)** handles centre-to-centre exchange. ## DNP3, the cousin — and the security gap 60870-5 is not alone. **DNP3 (IEEE 1815)** shares a common origin and does the same job; 60870-5 dominates in Europe, DNP3 in North America, and many devices speak both. The family's weakness is age: **60870-5-104 was specified without security**, so authentication and encryption are added by the **IEC 62351** series — now mandatory thinking given how exposed a routed telecontrol link is. This is the same control-system security discipline as [IEC 62443](/en/standards/iec-62443). ## Where it sits versus IEC 61850 It is easy to confuse 60870-5 with [IEC 61850](/en/standards/iec-61850), but they solve different problems. 61850 is the fast, model-rich communication *inside* a substation; 60870-5-104 is the *wide-area* link reporting that substation upward to the control centre. A modern station typically runs 61850 internally and 60870-5-104 to the centre, with [OPC UA (IEC 62541)](/en/standards/iec-62541) bridging to enterprise and analytics systems. ## Applicable industries Transmission and distribution control centres (TSO/DSO), Electrical substations and RTU/gateway vendors, Water, gas and district-heating utilities, SCADA integrators and protocol-test laboratories ## References & further reading - [IEC 60870-5 — overview (Wikipedia)](https://en.wikipedia.org/wiki/IEC_60870-5)