Technological Background Of The Iec 60870-5-101,104 Conversion - ABB EDS500 Series Function Manual

IEC 60870-5-101 and IEC 60870-5-104
{ l o c a l A S D U a d d r e s s 0 - 6 5 5 3 6 } >
< s e t i e c 1 0 4 i n t e r f a c e { 1 | 2 } r e m o t e - s t a t i o n a d d r e s s
{ s t a t i o n a d d r e s s } i p - a d d r e s s { I P a d d r e s s } >
< s e t i e c 1 0 1 i n t e r f a c e { 1 | 2 } f u n c t i o n { m a s t e r | s t a t i o n } >
< s e t i e c 1 0 1 i n t e r f a c e { 1 | 2 } p o l l { d a t a 1 | d a t a 2 } >
< s e t { i e c 1 0 1 | i e c 1 0 4 } i n t e r f a c e { 1 | 2 } c o n v e r t [ n o ]
a c k n o w l e d g e >
< s e t { i e c 1 0 1 | i e c 1 0 4 } i n t e r f a c e { 1 | 2 } c o n v e r t [ n o ] a s d u -
t y p e s >
< s e t { i e c 1 0 1 | i e c 1 0 4 } i n t e r f a c e { 1 | 2 } c o n v e r t [ n o ]
t i m e s t a m p s >
2.22.10 Technological Background of the IEC 60870-5-101,104
Conversion
The protocols IEC 60870-5-101 (abbreviated IEC-101) and IEC 60870-5-104 (abbreviated
IEC-104) are both protocols to transmit telecontrol data.
IEC 60870-5-101 is based on a serial transmission (e.g. via RS-232 and voice-frequency
telegraphy circuit lines)
IEC 60870-5-104 is based on a packet-oriented TCP/IP transmission.
As for the protocol design both protocols know a protocol data unit of the application layer
(APDU). In the case of IEC 60870-5-101 it is transmitted in a data frame in the format FT1.2
(defined in IEC 60870-5-2), in the case of IEC 60870-5-104 via TCP with port number 2404.
Both protocols divide a telegram into protocol control data (start indicator, Telegram length,
control field) and application data. The protocol control information are called application
layer protocol control information (APCI) for IEC 60870-5-104.
For IEC 60870-5-101 these are part of the frame format FT 1.2. The format of the application
data is almost identical for both protocols and is called service data unit of the application
layer (ASDU).
The protocol control information is fundamentally different for both protocols. While IEC
60870-5-104 supports polling mode (also called point-to-multipoint, multidrop or unbalanced
operation) as well spontaneous operation (also called point-to-point or balanced operation)
IEC 60870-5-104 only is defined for spontaneous operation.
The tasks of the protocol control information include establishing the link, transmission
repetition and confirmation of data as well as flow control. This applies to both protocols
although TCP already grants a safe end-to-end connection without telegram errors or loss.
Using IEC 60870-5-101, terminal devices are addressed with link addresses the size of one or
two bytes. The central office inserts the link address of the target station according to the
communication request and sends the telegram.
In polling mode all stations of a line get this telegram (polling mode divides terminals into
groups of devices) and the addressed device answers and inserts its own link address as
address.
While a send permission is granted in polling mode, this is not true for spontaneous
operation. Central office and station may send without polling.
74
Functions
1KGT151021 V000 1