IEC 60870 part 5 is one of the IEC 60870 set of standards which define
systems used for telecontrol in electrical engineering and power system
automation applications. Part 5 provides a communication profile for sending
basic telecontrol messages between two systems, which uses permanent directly
connected data circuits between the systems. The IEC Technical Committee 57
have developed a protocol standard for telecontrol, teleprotection, and
associated telecommunications for electric power systems. The result of
this work is IEC 60870-5. Five documents specify the base IEC 60870-5:
IEC 60870-5-1 Transmission Frame Formats IEC 60870-5-2 Data Link Transmission
Services IEC 60870-5-3 General Structure of
Application Data IEC 60870-5-4 Definition and Coding of
Information Elements IEC 60870-5-5 Basic Application
Functions IEC 60870-5-6 Guidelines for conformance
testing for the IEC 60870-5 companion standards
The IEC Technical Committee 57 has also generated companion standards:
IEC 60870-5-101 Transmission Protocols, companion standards especially for basic
telecontrol tasks IEC 60870-5-102 Companion standard for
the transmission of integrated totals in electric power systems
IEC 60870-5-103 Transmission Protocols, Companion standard for the informative
interface of protection equipment IEC 60870-5-104 Transmission Protocols,
Network access for IEC 60870-5-101 using standard transport profiles
IEC 60870-5-101103/104 are companion standards generated for basic
telecontrol tasks, transmission of integrated totals, data exchange from
protection equipment & network access of IEC101 respectively.
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 & balanced modes of
data transfer. Link address and ASDU 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 and low priority and transfer
the same using separate mechanisms. Possibility of classifying the data into
different groups 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 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 without / with
timestamps. Packed events of protection equipments
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 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 unitsor 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 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 and information
number 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 60870-5-104 IEC 60870-5-104 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 and routers with
different facility can be used to connect to the WAN. 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.
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, as many
of the other SCADA protocols developed around the same time. Though the IEC
technical committee 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.
References External links
j60870, IEC 60870-5-104 client and server Java library at openmuc.org,
GPL-licensed [1], IEC 60870-5-104103 Simulator