IEC 60870-5-104 Server communication protocol

Supported device types a and versions  
Communication line configuration
Communication station configuration
I/O tag configuration
Tell TELL commands
Literature
Document revisions

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• Originator ASDU address is 1 byte, it is defined as a line number.
• ASDU address is 2 bytes, it is defined as station address. For each station on a line, a different ASDU address must be defined.
• Cause of transmission is 2 bytes (it also contains Originator ASDU address)
• Information object address IS 3 bytes, it is defined as an I/O tag address.
• The following ASDU types in the direction of monitoring are implemented (from the D2000 system to the control station and also vice-versa in balanced mode):

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Note: For setting individual bits of the quality byte (SIQ for ASDU 1,2,30; DIQ for ASDU 3,4,31; QDS for ASDU 5..14,20,32..36), the flags FLA A (0.bit), FLB B (1.bit) .. FLH H (7.bit) are used.

For example:

• for ASDU 4: FLAA=DPI bit 0, FLBB=DPI bit 1, FLCC=0, FLDD=0, FLEE=BL bit, FLFF=SB bit, FLGG=NT bit, FLHH=IV bit.
• for ASDU 16: FLAA..FLE E Sequence number bits 0..4, FLFF=CY bit, FLGG=CA bit, FLHH=IV bit

The exception is the bits, which are set directly by a value (e.g. for ASDU 1, the 0.bit is not set by the FLA A flag but by the value of output I/O tag).
If the Invalid attribute is set for a new value, the highest bit (IV) will be set in the status byte of for all ASDUs (except for ASDU 21, which does not have a status byte).

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The following ASDU types in the direction of control are implemented (from the control station to D2000, also the opposite direction in balanced mode):

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Bits of "status" byte (SCO fro ASDU 45,58; DCO for ASDU 46,59; RCO for ASDU 47,60; QOS for ASDU 48..50,61..63) causes setting the FLA A (0.bit), FLB B (1.bit) .. FLH H (7.bit) flags with an exception for the bits which are directly set by the value of a variable (SCO bit 0, DCO and RCS bits 0-1). After receiving a response (positive/negative), the FLAA .. FLH H flags are set according to the bits of the "status" byte.

When writing values, the value of 6 [Activation] is expected as CauseOfTransmission. The response of the controlled station depends on the setting of the CMDC parameter. Originator ASDU address will be used the same as is in the received command.

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• Communication line category: TCP/IP-TCP
• TCP Parameters
  • Required to define the server parameters
  • Host: string containing at most 80 characters – the name of the network interface in form of INET (name or numerical address a.b.c.d, e.g. 192.168.0.1) used for receiving clients by the D2000 KOM process. If the name is ALL or *, the D2000 KOM process will listen on all network interfaces of the computer, where is running.
  • Port: TCP port number (0..65535), where the D2000 KOM process is listening.
  • Line number: will be used as Originator ASDU address (1 byte, 0-255).

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Note: Starting from D2000 version 7.02.004 the flags FLA  A to FLP P of the value of the communication line are used for informing about connected active clients. An active client is a client who after establishing the connection sent U-frame StartDT Act, i.e. asked for sending the data. The first connected active client will cause a change of flag FLA A to TRUE, the second flag FLBB, etc up to flag FLP P and continuing again with the first flag FLAA. If the client sends the StopDT Act U-frame  (requesting the server to stop sending data) or disconnects, the value of its flag will be changed to FALSE.

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• Communication protocol: IEC870-TCP Server.
• The station address is a decimal number within the range 0...65535, it defines the ASDU address. It can be specified as a decimal number or as a hexadecimal number with a hash at the beginning (e.g. #0A).

Note 2: The protocol supports sending long time stamps (CP56Time2a tag) in local time or UTC time with defined offset (see the Use monotonic UTC time+ parameter).

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The following parameters can be defined as station protocol parameters:

Table nr. 3Table 3

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If a keyword with an invalid value in the initialization string is found, a corresponding default value according to the table Table 3 will be used. Defined parameters, except for OIC, OCIC and FST are valid for the entire line - i.e. it is enough to define them for one station on the line.

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• I/O tag address is mapped to the Information object address, i.e. it has 3 bytes and must within the range of 0..16777215. It can be specified as a decimal number or as a hexadecimal number with a hash at the beginning (e.g. #0A).
  The I/O tag with an address starting with %IGNORE will be ignored.
  
• Input tags must be of particular types (Input tags must be of particular types (Ai, Ci, Di, Qi) for received ASDU, see Table 1.
• For a particular type of output tag (Ao, Dout, Co), it is necessary to set an ASDU type, that has to be used, see Table 2 and also Table 1 in the balanced mode.
• Archive for providing old values: if the client requires archive values using ASDU 250, the server sends:
  1. the values of the historical value specified by this input entry field,
  2. if the input entry field is not filled, then the values of the historical value that archives the I/O tag,
  3. if the specified historical value does not exist, then the values of the I/O tag that archives the control object of the specified I/O tag,
  4. if the control object does not exist (or the archive is not available), the server returns an error.
  Specification of a historical value allows configuring e.g. sending 10-minutes averages instead of sending all changes of given I/O tag.
• If the Destination Column is configured, then the values received from the address configured at the I/O tag and above are stored in the corresponding items (e.g. objects with addresses 10, 11, 12 ... according to the number of rows of the destination structure).

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-TCPSRV 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.

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• Ver. 1.0 – February 5th, 2004
• Ver. 1.1 – December 1st, 2004: extension - support of balanced mode
• Ver. 1.2 – June 15th, 2020: browsing support
• Ver. 1.3 – November 16th, 2023 (support for the Destination Column)

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