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Protokol DNP3 is a telemetryic telemetric protocol designed for communication of a master station (usually SCADA) with outstations (usually PLC, RTU, or other IED - Intelligent Electronic Devices). It was developed while IEC only worked on IEC60870-5 standards (IEC 870-5-101 and IEC 870-5-104).
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Range: the range of objects specified for explicit reading or writing. With explicit reading, it is also possible to retrieve all objects in a particular group or a range of objects. The values read in this way will then also be assigned to the I/O tags that do not have explicit reading configured , if the Group + Index matches retrieved data. Also, the read values can be assigned to items of a structured variable, if it is configured on the Destination tab.
The following ranges are supported:
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| Write function | Description |
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| Write (2) | Single-phase writing of objects (with a returned numeric code confirming successful write or specifying a write error). |
| Select (3) + Operate (4) | Two-phase write of objects that virtually excludes the possibility of error due to undetected interference on the line. |
| Direct Operate (5) | Single-phase write of objects. It returns a group, index, and write written value in addition to the return code. |
Direct Operate Non Return (6) | Single-phase write of an object without acknowledgment (the least secure but with the least load on the communication medium). |
Table 1 in the Supported Operations column for Write operation indicates which application functions are in compliance with the standard. Our implementation permits to use using application functions beyond the standard if a specific device supports them.
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Index: index of an object in a group
Source: the source of data:
- READ - data came in response to data read request - Read (1) function
- POLLED - data came in response to a Poll request - reading object group Class Objects (60)
- SPONTANEOUS - data came spontaneously - using Unsolicited Response (130) function
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Filtering in the list of objects: the browse window allows you to filter by the values displayed in each column. The values don't have to be entered completely. The notation *FILTERED EXPRESSION* is sufficient, where the asterisks represent any text before the start and end of the expression (e.g., *put* covers both input or output).
Total The total number of objects: the total number of objects in all object groups is displayed at the bottom left of the window.
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The Refresh button can be used to force the object list to be re-read from the device. By default, the KOM process reads the list of objects and their data types only for the first request and stores it in memory. Depending on the number of objects and the speed of the device, this reading may take a longer time. It then sends these this stored list to the CNF process(es), so that the next reading of the list in the DNP3 Item Browser window is fast.
Cancel
D2000 Cnf has a the recycling of browser window windows implemented. If the window is closed by the Cancel button or after selecting an object, it is actually only hidden and is available for browsing for another I/O tag within the same station, so that the list the of objects being viewed is preserved. Clicking on the cross at the top right corner will cause the window to actually close.
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| Command | Syntax | Meaning |
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| STWATCH | STWATCH StationName | Tell command sends commands for the reading of values of all configured I/O tagtags. This command sends Poll requests to all Classes according to the station parameter configuration and sends request requests for the reading of all I/O tags with the Explicit Read parameter active. |
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