IEC60870-5-101/103/104

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Introduction to IEC 60870-5-101

IEC 60870-5-101 [IEC101] is a standard for power system monitoring, control & associated communications for telecontrol, teleprotection, and associated telecommunications for electric power systems. This is completely compatible with IEC 60870-5-1 to IEC 60870-5-5 standards and uses standard asynchronous serial tele-control channel interface between DTE and DCE. The standard is suitable for multiple configurations like point-to-point, star, mutidropped etc.

Features

Supports unbalanced (only master initiated message) & balanced (can be master/slave initiated) modes of data transfer.
Link address and ASDU (Application Service Data Unit) addresses are provided for classifying the end station and different segments under the same.
Data is classified into different information objects and each information object is provided with a specific address.
Facility to classify the data into high priority (class-1) and low priority (class-2) and transfer the same using separate mechanisms.
Possibility of classifying the data into different groups (1-16) to get the data according to the group by issuing specific group interrogation commands from the master & obtaining data under all the groups by issuing a general interrogation.
Cyclic & Spontaneous data updating schemes are provided.
Facility for time synchronization
Schemes for transfer of files-Example:IED’s will store disturbance recorder file in the memory, When electrical disturbance is occurred in the field. This file can be retrieved through IEC103 protocol for fault analysis

Frame format

Character format of IEC 101 uses 1 start bit, 1 stop bit, 1 parity bit & 8 data bits. FT1.2 (defined in IEC 60870-5-1) is used for frame format of IEC 101 which is suitable for asynchronous communication with hamming distance of 4. This uses 3 types of frame formats – Frame with variable length ASDU, Frame with fixed length & single character. Single character is used for acknowledgments, fixed length frames are used for commands & variable lengths are used for sending data. The details of variable length frame is given below

Types supported

Single indication without / with 24 / with 56 bit timestamps.
Double indication without / with 24 / with 56 bit timestamps.
Step position information without / with 24 / with 56 bit timestamps.
Measured value – normalized, scaled, short floating point without / with timestamps.
Bitstring of 32 bit without / with timestamps.
Integrated totals (counters) without / with timestamps.
Packed events (start & tripping ) of protection equipment

Single commands
Double commands
Regulating step command
Set point commands of various data formats
Bitstring commands
Interrogation commands
Clock synchronization & delay acquisition commands
Test & reset commands

IEC 101 Frame Format, Variable length

Data unit

Name

Function

Start Frame

Start Character

Length Field (*2)

Start Character (repeat)

Control Field

Link Address (0,1 or 2)

Indicates start of Frame

Total length of Frame

Repeat provided for reliability

Indicates control functions like message direction

Normally used as the device / station address

Data Unit Identifier

Type Identifier

Variable Structure Qualifier

COT (1 or 2)

ASDU Address (1 or 2)

Defines the data type which contains specific format of information objects

Indicates whether type contains multiple information objects or not

Indicates causes of data transmissions like spontaneous or cyclic

Denotes separate segments and its address inside a device

Information Object

Information Object-2

—

Information Object-m

Information Object Address (1 or 2 or 3)

Information Elements (n)

—

Provides address of the information object element

Contains details of the information element depending on the type

Stop Frame

Checksum

Stop Char

Used for Error checks

Indicates end of a frame

Introduction to IEC 60870-5-103

IEC 60870-5-103 [IEC103] is a standard for power system control and associated communications. It defines a companion standard that enables interoperability between protection equipment and devices of a control system in a substation. The device complying with this standard can send the information using two methods for data transfer – either using the explicitly specified application service data units (ASDU) or using generic services for transmission of all the possible information. The standard supports some specific protection functions and provides the vendor a facility to incorporate its own protective functions on private data ranges.

Frame format

IEC 103 uses FT1.2 (defined in IEC 60870-5-1) for frame format having options of Frame with variable length, Frame with fixed length & single character similar to IEC 101. Single character is used for acknowledgments, fixed length frames are used for commands & variable lengths are used for sending data. However the frame format of IEC 103 differs from IEC 101 in information object address which is split into function type (ftype) and information number (inumber) in IEC 103. Also IEC 103 can have only single information object in a frame whereas IEC 101 can have multiple information objects. Many of the field sizes are also restricted in IEC 103. The details of variable length frame is given below.

Supported Types

Type 1 — Time-tagged message
Type 2 — Time-tagged message with relative time
Type 3 — Measurands I
Type 4 — Time-tagged measurands with relative time
Type 5 — Identification
Type 6 — Time synchronization

Type 7 — Start of General interrogation
Type 8 —- General interrogation termination
Type 9 — Measurands II
Type 10 — Generic data
Type 11 — Generic identification
Type 23–31 — Used for transferring disturbance files

IEC 103 Frame Format, Variable length

Data unit

Name

Function

Start Frame

Start Character

Length Field (*2)

Start Character (repeat)

Control Field

Link Address (0,1 or 2)

Indicates start of Frame

Total length of Frame

Repeat provided for reliability

Indicates control functions like message direction

Normally used as the device / station address

Data Unit Identifier

Type Identifier

Variable Structure Qualifier

COT (1 or 2)

ASDU Address (1 or 2)

Defines the data type which contains specific format of information objects

Indicates whether type contains multiple information objects or not

Indicates causes of data transmissions like spontaneous or cyclic

Denotes separate segments and its address inside a device

Information Object

Function Type

Information Number

Information Elements (n)

Provides function type of the protection equipment used

Defines the information number within a given function type

Contains details of the information element depending on the type

Stop Frame

Checksum

Stop Char

Used for Error checks

Indicates end of a frame

Introduction to IEC 60870-5-104

IEC 60870-5-104 (IEC 104) protocol is an extension of IEC 101 protocol with the changes in transport, network, link & physical layer services to suit the complete network access. The standard uses an open TCP/IP interface to network to have connectivity to the LAN (Local Area Network) and routers with different facility (ISDN, X.25, Frame relay etc.) can be used to connect to the WAN (Wide Area Network). Application layer of IEC 104 is preserved same as that of IEC 101 with some of the data types and facilities not used. There are two separate link layers defined in the standard, which is suitable for data transfer over Ethernet & serial line (PPP – Point-to-Point Protocol). The control field data of IEC104 contains various types of mechanisms for effective handling of network data synchronization.

The security of IEC 104, by design has been proven to be problematic,[2] as many of the other SCADA protocols developed around the same time. Though the IEC technical committee (TC) 57 have published a security standard IEC 62351, which implements end-to-end encryption which would prevent such attacks as replay, man-in-the-middle and packet injection. Unfortunately due to the increase in complexity vendors are reluctant to roll this out on their networks.

Brodersen auto generation of IEC 60870-5-101/103/104 applications

Setup of IEC 60870 applications is made easy using the RTU Configuration Generator – a ‘wizard’ that allows rapid creation of a WorkSuite application from configuration details that are entered in an EXCEL spread sheet. The spread sheet includes multiple work sheets for managing IEC 60870 setup details such as RTU address, IP address, IO channels, tag names and communication port settings.

1. The spread sheet is loaded with default settings, making it quick to set the parameters that may be unique for your application

eg. how much IO and site information.

2. Once you have completed the spread sheet configuration, select ‘Generate’ and the application is checked and then created.

If you selected options ‘download project’ and ‘open WorkSuite’ then the project will also be sent to the RTU and WorkSuite loaded.

3. All of the necessary logic functions used to determine alarm status, parameters used to control various communications methods and all of the variables listed in the spread sheet have now been loaded in to the application (and sent to the RTU).

4. The example here shows how the setup of a IEC 60870-5-104 application.