IEC 60870-5-101/104 Protocols Overview

Introduction

IEC 60870-5 is an international standard released in the early 1990s by the International Electrotechnical Commission (IEC). This standard provides a communication profile for telecontrol, teleprotection, and associated telecommunications characteristics for electric power systems. It is widely used today for other infrastructures, including water applications in Europe and Asia.

The IEC 60870-5-101 and IEC 60870-5-104 protocols are companions to the IEC 60870-5 standards that relate to transmission protocols.

IEC 60870-5-101

The IEC 60870-5-101 protocol is based on the EPA (Enhanced Performance Architecture). This protocol defines only the physical link and application layers of the OSI model. IEC 60870-5-101 is used primarily on serial links with relatively slow transmission media. This standard conforms to baud rates of up to 9600 bit/s, although much higher baud rates (<115200 bit/s) are being used.

IEC 60870-5-104

The IEC 60870-5-104 protocol is an extension of the IEC 60870-5-101 protocol. There are changes in transport, network, link & physical layer to open networking.

IEC 60870-5-104 enables communication between control stations and substations in a standard TCP/IP network. The TCP protocol is used for connection-oriented data transmission. To have connectivity to LANs and routers with different facilities (frame relay, etc.), connect it to the WAN. The application layer of IEC 104 is the same as that of IEC 60870-5-101, except that some data types and facilities are not used. There are separate link layers defined in the standard, which facilitates the transfer of data over Ethernet and serial lines.

Supported Protocol Features

Features of the IEC 60870-5-101/104 protocols:

general interrogation
clock synchronization
events transmission (time-stamped or not)
balanced and unbalanced communications
counter interrogation
command transmission modes (select and execute mode)

Supported Data Types

The IEC 60870-5-101/104 protocols include these data types:

discrete inputs/outputs (single or double)
measured values (with different formats)
integrated totals
commands

Protocol Characteristics

The table lists the characteristics for the supported RTU protocols:

Protocol	Characteristics
IEC 60870-5-101 master	up to 32 slaves (1 session for each slave and up to 5 sectors per session), individual database definition for each sector
IEC 60870-5-101 master	up to 5000-point database for all sectors including predefined commands
IEC 60870-5-101 slave	up to 5000- point database for data objects of all supported types
	up to 100,000-event queue for all data types
	supports clock synchronization from a master, CPU or NTP
	configurable data link address CAA (Common ASDU Address) and IOA
	event time-stamping configurable by type (None, CP24, CP56)
IEC 60870-5-104 server	client IP address validation list (up to 10 IP addresses)
	up to 4 concurrent client connections with configurable TCP service port (standard is 2404)
	up to 5000-point database for data objects of all supported types
	up to 100,000-event queue for all data types in all clients (each client has a dedicated event buffer)
	event time-stamping configurable by type (None, CP56)
	configurable CAA (common ASDU address) and IOA
IEC 60870-5-104 client	up to 5000-point database for all sectors including predefined commands up to 64 servers connections supported connections share common channel configuration dedicated connection for each session and sector configuration dedicated destination IP address and port settings for each connection

Interoperability Lists

The interoperability list (defined by the standard) facilitates interoperability between devices from different manufacturers. In the list, the function range is described for each device by marking the applicable functions.

NOTE: Refer to the IEC interoperability list for this RTU module in Appendices.