The document outlines various communication protocols, specifically focusing on IEC 60870 standards for telecontrol in electrical systems, including IEC 101 and IEC 104 for reliable data transmission. It explains the layers of the Enhanced Performance Architecture (EPA) model used in these protocols, detailing the application, data link, and physical layers, as well as transmission mechanisms. Key differences between IEC 101 and IEC 104 are highlighted, particularly their use cases in SCADA systems and network communications.

1. PROTOCOLS
IEC 101 – IEC 104

2. What is protocol ?
• Protocol is set of rule’s it is used for communication between two
devices.
• His can be applied to various fields, such as diplomatic procedures,
scientific experiments, or organizational behavior.
Technology and Networking :
In technology, particularly in computer networking, a protocol is
a standardized set of rules for communicating between devices. These
rules determine how data is formatted, transmitted, and processed.

3. Technology and Networking
• HTTP (HyperText Transfer Protocol): Used for transmitting web
pages over the internet.
• TCP/IP (Transmission Control Protocol/Internet Protocol): A suite
of protocols used for data transmission over networks.
• SMTP (Simple Mail Transfer Protocol): Used for sending emails.

4. Tele-control protocols
IEC 60870 5 101
‐ ‐ protocol (Serial mode communication from RTU to
Control Center)
IEC 60870 5 104
‐ ‐ protocol (network mode communication from RTU to
Control Center)
IEC 60870 6 502
‐ ‐ ( ICCP) protocol (between two Control Canters)
IEC 60870 5 103
‐ ‐ protocol (for communication between IEDs in a
Substation)
DNP 3.0 Protocol (Serial)
DNP 3.0 Protocol (TCP/IP)

5. RLDC
SLDC SLDC
Area-LDC Area-LDC
RTU RTU RTU
Communication Channel for Information flow
Wide band Commn
MW/ FO
Wide band Commn
Wide band/ PLC
Commn
Three of the most important part of a SCADA system: Master Station, Remote Terminal
(RTU, PLC, IED), and communication between them

7. WHAT IS IEC-870-5 ?

8. WHAT IS IEC870-5
PROTOCOL?

9. IEC 60870-5 Protocol
Based on the reduced communication reference model called Enhanced Performance
Architecture (EPA)
Companion standards IEC 60870 5 101 and IEC 60870 5 104
‐ ‐ ‐ ‐ are derived from the IEC 60870‐
5 protocol standard definition
EPA includes three layers of the OSI model
Application layer
Data Link layer
Physical layer

10. 101
104
 IEC 101 is an international standard protocol developed by
the International Electrotechnical Commission (IEC) for
telecontrol equipment and systems with a focus on reliable
communication in electric power and industrial automation.
 It is primarily used in SCADA (Supervisory Control and
Data Acquisition) systems to ensure reliable data
transmission between remote terminal units (RTUs) and
control centers.
 IEC 60870-5-104 (commonly referred to as IEC 104) is
an extension of IEC 101 for use over network
connections, particularly using TCP/IP.
 It provides a communication protocol for transmitting
data between control stations and substations over IP-
based networks.

11. WHAT IS EPA STRUCTURE?
Application
Presentation
Session
Transport
Network
Data link
Physical
Data Link
Physical
3 Layer
‐
7 Layer
‐
EPA
OSI
1) Short Reaction Time
2) Reduced Transmission Bandwidth
Reason for 3 Layered
‐ Structure of EPA

12. Physical Layer :
Information (data)
bit : 8 bit
Start bit:1 ,
Stop bit : 1
Parity bit : Even
Data Link Layer
Standard Frame Format : FT 1.2 (frame
format of IEC 101 which is suitable for
asynchronous communication)
Data Transmission at Link Layer ( Station address field Length : 1 or 2 bytes )
Unbalanced Mode :
Transmitted messages are categorized on two priority classes( Class 1 & Class 2 )
Balanced Mode :
All the messages are sent, No categorization of Class 1 and Class 2
Network Layer : Not defined as 870 5 101 as it is not IP based
‐ ‐
Application Layer
Length of header fields of data structure are:
‐ Station address 1 or 2 byte ( User defined )
‐ ASDU Address : 1 or 2 bytes
‐ Information Object address : 2 bytes

13.  As balanced communications are point to point
‐ ‐ the link address is redundant, but
may be included for security
 ASDU contains address of the controlling station in the ‘control direction’, and the
address of the controlled station in the ‘monitoring direction’
 Unique address for each data element
IEC 60870-5-101 Data Frame

14.  At the link layer, all devices are equal
 restricted to point to point and to
‐ ‐ multiple
point to point
‐ ‐ configurations
 Collision avoidance by‐
 Full duplex point to point connection (RS232
or four wire RS485)
 Designated master polls slaves on n/w
 Only Master device can transmit primary frames
 Collision avoidance is not necessary since slave device
cannot initiate exchange
 If the slave device responds with NACK: (requested
data not available) the master will try again until it gets
data, or a response time out
‐ occurs
Link Layer Balanced Transmission Link Layer Unbalanced Transmission
IEC 60870-5-101 Data Exchange

15.  Based on data transmission via Ethernet (TCP/IP)
 An extension of IEC 101 protocol with the changes in transport, network, link & physical
layer services to suit the complete network access
 Application layer of IEC 104 is same as that of IEC 101 with some of the data types and
facilities not used
 offers considerable benefits compared with the serial data transmission ‐
 Higher level safety
 Flexible network layout
 Numerous network utilities
 Simplified management of connected devices
 Reduced time and cost for maintenance and servicing
 The security of IEC 104, by design has been proven to be problematic
IEC 60870-5-104

16. IEC 60870-5-104
 Operation of the lower layers of IEC 60870 5 104
‐ ‐ is completely different from that of
the IEC 60870 5 101.
‐ ‐
 These layers correspond to all the layers below the application layer,
 Architectures of these layers are concerned with how message transports happen.

17. Thank you