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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 (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:
- the values of the historical value specified by this input entry field,
- if the input entry field is not filled, then the values of the historical value that archives the I/O tag,
- 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,
- 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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Literature
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title | An example of communication |
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See an example of communication for the IEC 870-5-104 protocol, which contains the configuration of the IEC 870-5-104 client and server. |
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You can read a blog about the IEC 870-5-104 protocol: |
Document revisions
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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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