Exceptions to the store-forward data
- Last UpdatedFeb 09, 2023
- 2 minute read
During store-forward recovery some of the tag data includes unusual or odd data. This data represents outliers of expected data and carries a duplicate timestamp to the previous data value. OSIsoft has identified this data as marked with the quality detail RPC Reconnect (44).
Example of expected data
|
Start Time |
End Time |
Value |
Quality |
Quality Detail |
|---|---|---|---|---|
|
03:34:35.781 |
03:34:35.781 |
95 |
0 |
192 |
|
03:34:36.780 |
03:34:36.780 |
94 |
0 |
192 |
|
03:34:37.777 |
03:34:37.777 |
93 |
0 |
192 |
|
03:34:38.776 |
03:34:38.776 |
92 |
0 |
192 |
|
03:34:39.790 |
03:34:39.790 |
91 |
0 |
133 |
|
03:35:31.778 |
03:35:31.778 |
90 |
0 |
44 |
|
03:35:35.772 |
03:35:35.772 |
89 |
0 |
192 |
|
03:35:37.769 |
03:35:37.769 |
88 |
0 |
192 |
Example of unexpected or odd data (duplicate timestamp)
|
Start Time |
End Time |
Value |
Quality |
Quality Detail |
|---|---|---|---|---|
|
03:34:35.781 |
03:34:35.781 |
95 |
0 |
192 |
|
03:34:36.780 |
03:34:36.780 |
94 |
0 |
192 |
|
03:34:37.777 |
03:34:37.777 |
93 |
0 |
192 |
|
03:34:38.776 |
03:34:38.776 |
92 |
0 |
192 |
|
03:35:31.778 |
03:34:39.790 |
89 |
0 |
133 |
|
03:35:31.778 |
03:34:39.790 |
1013 |
0 |
44 |
|
03:35:33.775 |
03:35:33.775 |
91 |
0 |
192 |
|
03:35:35.772 |
03:35:35.772 |
90 |
0 |
192 |
|
03:35:37.769 |
03:35:37.769 |
89 |
0 |
192 |
|
03:35:38.769 |
03:35:38.769 |
88 |
0 |
192 |
During the testing, OSIsoft tried eliminating this data by discarding the data with a quality detail of RPC Reconnect (44), but found this would also eliminate valid data found in some changing data that have encountered a store-forward backfill. Since this is what is coming from the Wonderware Historian, the data is written to the associated PI point of the tag.
OSIsoft continues to look at resolving this issue, but the approach requires caching data and doing a look ahead around data values for this particular case. Caching the data would increase the memory footprint of the Wonderware connector significantly to solve a problem that was rarely seen.