Use Device History Files
- Last UpdatedJul 18, 2023
- 2 minute read
To make the long-term storage of logged data easier to organize and more accessible, Plant SCADA uses a system of rotational history files to store historical data. To use this system, you need to specify how many device history files you want to keep. For example, if you want to keep 10 history files, they would be saved rotationally as illustrated below:
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When Plant SCADA begins logging, data is written to a file called <filename>.txt or <filename>.dbf, depending on the type of device.
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At midnight the following Sunday, the file <filename>.txt is renamed to <filename>.001 and a new <filename>.txt is created.
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At midnight the following Sunday, the file <filename>.001 is renamed to <filename>.002, <filename>.txt is renamed to <filename>.001, and then a new <filename>.txt is created.
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After week 10, the first file is overwritten (week 11 in the first cycle).
The history files will not be created if the device is not being used.
Note: To archive your data for long-term storage, manually back up your history files before they are overwritten. The 10 history files are in addition to the default data file that is saved for each device.
By default, Plant SCADA uses 10 files (if history files are specified). You can change the default by specifying the number of files to use, for example:
|
No. Files |
20 |
|
Comment |
Plant SCADA uses twenty files for the data |
The maximum number of files you can specify is 999.
You can also specify the period between files, that is, when a new history file is used, for example:
|
Period |
Comment |
|---|---|
|
1:00:00 |
Use a new file each hour |
|
6:00:00 |
Use a new file every six hours |
|
72:00:00 |
Use a new file every three days |
|
Monday |
Use a new file each week beginning on Monday |
|
15th |
Use a new file every month beginning on the 15th of each month |
|
25th June |
Use a new file every year beginning on the 25th of June |
Note: Marked improvement in system performance is observed when a period of one week or more is specified.
You can also specify the time of day to synchronize the beginning of the history file, for example:
|
Time |
Comment |
|---|---|
|
6:00:00 |
Synchronize the file at 6:00 am |
|
12:00:00 |
Synchronize the file at 12:00 midday |
|
18:30:00 |
Synchronize the file at 6:30 pm |
The first file does not actually begin at this time: the first file begins when you start your runtime system. The time and period together determine when new history files are created, for example:
|
Time |
Period |
|---|---|
|
6:00:00 |
Monday |
In the above example, Plant SCADA creates a new file each Monday at 6:00am. If you start your runtime system at 7:30am on Sunday, your first file only contains 22.5 hours of data. If you leave your system running, subsequent files start each Monday at 6:00am, and contain one full week of data.