IEC 60870-5-101 communication protocol

Supported device types and versions 
Communication line configuration
Communication station configuration
Line protocol parameters
I/O tag configuration
Tell commands 
Literature
Changes and modifications
Document revisions

Supported device types and versions

This protocol (known also as IEC 870-5-101 or IEC-101) supports:

• standard IEC 60870-5-101:2003 in both "unbalanced" (master and slave) and "balanced" modes,
• redundancy of communication lines according to the so-called Norwegian convention (Norwegian IEC 870-5-101 User Conventions).

Communication line configuration

Line categories:

• Serial,
• Serial Line Redundant,
• Serial System&Line Redundant,
• SerialOverUDP Device Redundant,
• SerialOverUDP Line Redundant,
• SerialOverUDP System&Line Redundant,
• RFC2217 Client.

Implementation is, according to the IEC870-5-101 standard, as follows:

• The originator ASDU address is not present.
• ASDU address is 1 byte, it is defined as the station address. ASDU addresses of all stations on one line must be different.
• The cause of transmission is 1 byte (does not contain Originator ASDU address).
• The information object address is 2 bytes, it is defined as an I/O tag address.

If a redundant communication on two lines is required (Norwegian conventions) use the line categories Serial Line Redundant or SerialOverUDP Device Redundant.

If you require the system-redundant communication, use SerialOverUDP System&Line Redundant or Serial System&Line Redundant line categories. Providing that, this communication should be also network redundant, enter "Secondary line" for both "A System" and "B System". This configuration then works in such a way that it concurrently sends and receives data from two systems and each is network-redundantly connected in compliance with the so-called Norwegian convention (Norwegian IEC 870-5-101 User Conventions).

Communication station configuration

• Communication protocol "IEC 870-5-101 balanced", "IEC 870-5-101 unbalanced primary (Master)" or "IEC 870-5-101 unbalanced secondary (Slave)".
• The station address is a decimal number in range 0 - 255 and is used in the protocol as the ASDU address.
• The synchronization of the station real-time may be enabled also for the protocols "master" and "balanced - station A (controlling)". Set the synchronization period to a nonzero value. The synchronization is executed by ASDU 103 "Clock synchronization command" in the local time according to settings of the D2000 System.

The Browse button opens a browsing dialog for the station address. If the communication is functional, a dialog with the ASDU addresses received so far is displayed. The Refresh button can be used to clear the list of received ASDU addresses.

Line protocol parameters

Configuration dialog box - tab Protocol parameters.
They influence some optional parameters of the protocol. The following station protocol parameters can be set:

Table 1

I/O tag configuration

Possible value types of I/O tags: Ai, Ao, Di, Dout, Ci, Co, Qi

I/O tag address is a numerical address of data object IOA (in range 0 - 65535).

In case of command direction in master or balanced mode is necessary to configure a proper ASDU type:

In case of slave or balanced mode je is necessary to configure je proper ASDU type in v data direction:

Note 1: Individual bits of a quality byte (SIQ for ASDU 1,2,30; DIQ for ASDU 3,4,31; QDS for 5-14,20,32-36) set the attributes FLA (0.bit), FLB (1.bit) ..FLH (7.bit).
Example:
for ASDU 4: FLA=DPI bit 0, FLB=DPI bit 1, FLC=0, FLD=0, FLE=BL bit, FLF=SB bit, FLG=NT bit, FLH=IV bit.
for ASDU 16: FLA..FLE Sequence number bits 0..4, FLF=CY bit, FLG=CA bit, FLH=IV bit

Moreover:

• if bit IV (Invalid) is set, the status of value will be Invalid
• if one of the NT (Not topical), SB (Substituted), BL (Blocked), OV (Overflow), CA (Counter adjusted), or CY (Counter overflow) bits are set in their respective ASDU types, the status of value will be Weak.

* - T-bit from the value of ASDU sets the attribute FI into the value of I/O tag which has value type Ci/Ai and they are interpreted as numbers -64 up-to +63.

** - ASDU 17 and 38: the value of SEP byte sets the attributes FLA (0.bit), FLB (1.bit) up-to FLH (7.bit), following 2 bytes (CP16Time2a) are interpreted as a positive number (0-60 000) into the value of I/O tag with value type Ci/Ai or as a relative time (0-60 seconds) into the value of I/O tag with TiR value type.

*** - ASDU 18, 39 and 40: value of SPE(ASDU 18,39) or OCI (ASDU 40) byte sets the attributes FLI (0.bit), FLJ (1.bit) up-to FLP (7.bit). The value of byte QDP sets the attributes FLA (0.bit), FLB (1.bit) up-to FLH (7.bit), following 2 bytes (CP16Time2a) are interpreted as a positive number (0-60 000) into the value of I/O tag with value type Ci/Ai or as a relative time (0-60 seconds) into the value of I/O tag with TiR value type.

Note 2: When using the system and line redundant categories of lines, the status of line and station is formed by a logical sum of all used lines. It means, that if the redundant system consists of four lines and just one line is working, the status of the station and line is all right. The status of lines is presented with the help of special input or output I/O tag (of integer and real type, i.e. Ai/Ao/Ci/Co). The name of this I/O tag has this format: [line_name]_SystemStatus (e.g. for line L.Test it is M.Test_SystemStatus). The value of the I/O tag represents the binary format of the status of N-tuple lines. If the first three lines are okay but the last one does not work (SystemB/SecondaryLine) i.e. [FALSE, TRUE, TRUE, TRUE], I/O tag has the value 0b0111, i.e. 7.
The order of lines mapped to individual bits is [SystemB/SecondaryLine,  SystemB/PrimaryLine, SystemA/SecondaryLine, SystemA/PrimaryLine].

Browse

For the I/O tags, it is possible to discover the list of objects, as long as the KOM process is running and communication with a station is established.
Clicking the Browse button opens the IEC870-5-101 Item Browser window and displays a list of objects that have been read so far. The object list is created dynamically as a result of received messages.

The list of objects is dynamic, i.e. when a new value arrives in the KOM process, it is updated. Filtering in individual columns is also supported, asterisks can be used in the mask (e.g. *Short*).

Double-clicking on a particular line will cause the Address parameter to be inserted into the configuration of the I/O tag from which the IEC870-5-101 Item Browser window was opened.

The Refresh button clears the list of values in both the CNF and the KOM process.

The Value column contains the received value.

Tell commands

Literature

• Telecontrol equipment and systems Part 5-101: Transmission protocols – Companion standard for basic telecontrol tasks (IEC 60870-5-101:2003), http://www.iec.ch.
• Telecontrol equipment and systems Part 5-2: Link transmissions procedures (IEC 60870-5-2:1992), http://www.iec.ch.
• Norwegian IEC 870-5-101 User Conventions, Approved version Revision no. 2.0, http://www.statnett.no.

Changes and modifications

• June 2015 - implemented Source Flags parameter

Document revisions

• Ver. 1.0 - November 22nd, 2007 - document creating
• Ver. 1.1 - April 22nd, 2009 - document updating
• Ver. 1.2 - June 8th, 2015 - new parameter implemented
• Ver. 1.3 – June 15th, 2020: browsing support