IEC 60870-5-101 (also known as IEC 870-5-101) is an international standard, released at the beginning of the
90ies by the IEC (International
Electrotechnical Commission). The protocol has found widespread use in the
energy sector, and is still used today. It is based on the EPA architecture (Enhanced
Performance Architecture) and defines only the physical link and application
layers of the OSI model.
IEC 60870-5-101 is primarily used with relatively slow transmission media on the
asynchronous V.24 interface. The standard promises baud rates of up to 9600
bit/s, with much higher baud rates (<115200 bit/s) actually being used.
X.24/X.27 interfaces with baud rates up to 64000 bit/s, also part of the
standard's description, could not establish themselves and are rarely used.
IEC 60870-5-101 is a 'Companion Standard', extended by these further standards:
defines different frame formats, though IEC 60870-5-101
uses only the FT1.2 format
IEC 60870-5-2 defines the link layer transmission mode
defines the basic application data structure
IEC TS 60870-5-601
defines "Conformance Test Cases" for IEC 60870-5-101
IEC 60870-5-101 was extended and more precisely defined in 2001 by Amendment
Interoperability between devices by different vendors is ensured by the
interoperability list, which is defined by the standard. In the list, the
function range is defined for each device by marking the applicable functions.
The common denominator between different vendor lists limits the
possible function range.
As the original standard left more room for interpretation, there were many
different implementations on a wide range of different devices many of which are
mutually incompatible. To remedy this situation, major energy utilities, such as RWE, Bayernwerke (E.ON), have developed their own IEC 60870-5-101 based standards.
The "Norwegian IEC 870-5-101 User Convention", managing line redundancy in particular, has found
wide acceptance in Scandinavian countries.
IEC 60870-5-101 is known for the resilience of its link layer and for its simply
structured application layer. The main focus was placed on on performance
definition, so that some information needed for data decoding is not
transmitted. For data decoding to work, parameter settings such as information
object length, ASDU address length etc. need to be correct. This is not much of a
problem, as interoperability lists help to achieve this.
Fragmentary protocol definition has its disadvantages, especially with
respect to line redundancy where a range of diverging implementations exist. A clear
definition of project-specific requirements is recommended.
In addition to standard protocol functionalities, IEC 60870-5-101
also allows for extensions with proprietary vendor-specific functions. Though
not used too often, this also carries the risk of incompatibilities.
IEC 60870-5-101 Companion Standard IEC 60870-5-5, IEC 60870-5-4, IEC 60870-5-3
balanced IEC 60870-5-2 IEC 60870-5-1 (FT 1.2)
unbalanced IEC 60870-5-2 IEC 60870-5-1 (FT 1.2)
Supported Information Types
Regulating step command
Single indication [1 Bit] with quality
Single indication [1 Bit] with quality and time tag
Double indication [2 bit] with quality
Double indication [2 bit] with quality and time tag
Measured scaled value with quality
Measured scaled value with quality and time tag
Measured normalized value with quality
Measured normalized value with quality and time tag
Measured floating point value with quality
Measured floating point value with quality and time tag
Bitpattern [32 bit] with quality
Bitpattern [32 bit] with quality and time tag
Counter value with quality
Counter value with quality and time tag
Step position value with quality
Step position value with quality and time tag
Event of protection equipment with quality and time tag
PCM, Full-duplex operation in balanced mode, half-duplex operation in unbalanced mode
Asymmetric transmission (unbalanced mode): Party line or point to point Symmetric transmission (balanced mode): Only point to point is possible
On-demand transmission (e. g. single indications, analogs, ...) Spontaneous transmission (e. g. single indications with time tag, ...) Direct command transmission (with select before operate) Clock synchronization File Transfer
Common Address of ASDU: 1..65535 Information object address: 1..16777215 Link address: 0..65535
Implemented Protocol Stacks
IEC 60870-5-101, Dialup Master
IEC 60870-5-101, Master
IEC 60870-5-101, Slave
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