It is possible to read out up to 10 sequential event records in one event select/read transaction. The number of sequential event records to be returned for reading is written to the Num of records register (49250) in front of the selection register. The number can be written once before a select/read event transaction. If this number is never written, only one event record is returned.
If the Modbus client requests multiple event records, the returned records should also be read out by the client. One record consists of 11 registers, two records of 22 registers and so on. The read length must thus be adjusted depending on the number of records requested.
The selection/read operation is otherwise identical to the single-record read case. The next records to be returned always continue from the last record in the previous read operation.
Reading out more event records than are available in the internal event buffer
The requested amount of event records is always returned for reading. For example, if 10 event records are requested, but the protection relay only contains five event records, the last valid event record is repeated (duplicated) in the last five event records returned. The easiest way to detect the duplication is to check the sequence number of the event records. The sequence numbers remain similar to the duplicated event records.
Extended event record structure
The extended register addresses are 49250 and 49263...49361.
| Address | Register | Values | Description |
|---|---|---|---|
| 49250 | Num of records | 1...10 | Write: Number of Event structures |
| 49251 | Selection | Write: Selection code | |
| 49252 | Sequence Number 1 | Event record 1 | |
| 49253 | Unread records left 1 | ||
| 49254 | TimeStamp 1 | ||
| 49255 | TimeStamp 1 | ||
| 49256 | TimeStamp 1 | ||
| 49257 | TimeStamp 1 | ||
| 49258 | Event Type 1 | ||
| 49259 | Data Object Id 1_1 | ||
| 49260 | Data Object Id 2_1 | ||
| 49261 | Data Value 1 | ||
| 49262 | Data Value 1 | ||
| 49263 | Sequence Number 2 | Event record 2 | |
| 49264 | Unread records left 2 | ||
| 49265 | TimeStamp 2 | ||
| 49266 | TimeStamp 2 | ||
| 49267 | TimeStamp 2 | ||
| 49268 | TimeStamp 2 | ||
| 49269 | Event Type 2 | ||
| 49270 | Data Object Id 1_2 | ||
| 49271 | Data Object Id 2_2 | ||
| 49272 | Data Value 2 | ||
| 49273 | Data Value 2 | ||
| 49274 | Sequence Number 3 | Event record 3 | |
| : | : | : | : |
| 49285 | Sequence Number 4 | Event record 4 | |
| : | : | : | : |
| 49296 | Sequence Number 5 | Event record 5 | |
| : | : | : | : |
| 49307 | Sequence Number 6 | Event record 6 | |
| : | : | : | : |
| 49318 | Sequence Number 7 | Event record 7 | |
| : | : | : | : |
| 49329 | Sequence Number 8 | Event record 8 | |
| : | : | : | : |
| 49340 | Sequence Number 9 | Event record 9 | |
| : | : | : | : |
| 49351 | Sequence Number 10 | Event record 10 | |
| 49352 | Unread records left 10 | ||
| 49353 | TimeStamp 10 | ||
| 49354 | TimeStamp 10 | ||
| 49355 | TimeStamp 10 | ||
| 49356 | TimeStamp 10 | ||
| 49357 | Event Type 10 | ||
| 49358 | Data Object Id 1_10 | ||
| 49359 | Data Object Id 2_10 | ||
| 49360 | Data Value 10 | ||
| 49361 | Data Value 10 |