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Status Text
Defines a status text of the historical value. The status text allows for redefining individual values' identification for the historical value.
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Technical units
Technical units of the historical value. Maximum: 12 symbols. Possibility to use the Dictionary (to open click the CTRL+L).
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Note: The above-described fact implies, that the object to archive directly specifies the type of historical value - simple, one-column, or structured historical oneones. So all changes in the configuration of the historical value have a direct effect on its functionality, mainly if the object is used in other historical values.
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- Periodical - writing values in the archive are periodical. The archiving process stores the archive object value into in the archive in defined time moments. Timestamp (the time of value) is not determined by the timestamp of the archived object value (e.g. an I/O tag), but by the time when the value is periodically written into the archive.
Reading the values stored periodically by means of the D2000 system (ESL: GETARCHARR, GETARCHVAL, GETARCHROW, GETARCHCOL, GETARCHSTRUCT, D2000 ObjApi: GetArchivData, D2000 VBApi: VBApiGetArchData, D2000 WorkBook) follows the rule that the archive object's value out of time moments given by the period, is unknown (invalid). The result of the data reading is therefore given by the resampling and the begin (BT) and end (ET) time as follows:- resampling (step) = 0
The reading results are all the values, the time of which belong belongs to the interval <BT, ET>. - resampling (step) <> 0
The reading result is an array of values with timestamps contiguously:
BT+0*step, BT+1*step, BT+2*step, ..., BT+N*step.
The number of values is given by the end of the time interval (ET). The value of the array item is invalid if a record with the same timestamps does not exist in the archive database. If such a record exists, it is returned as a value of the array item. The above facts imply that when reading periodical data, it is necessary (advisable):- to adjust BT exactly to some of the object archiving moments, given by the period and time offset of the archiving.
- resampling value (step) must be an integer multiple of the archiving period.
- ET = BT + (N-1)*step, where N is an integer number: the number of values in the final selection.
Note: The statistical archive, as far as reading is concerned, behaves as a periodical archive.
- resampling (step) = 0
On value change - all the value changes of the archive object, which are not filtered out by the value filter, are stored in the archive.Kotva sa_filter1 sa_filter1
Reading of values stored by using a filter by means of the D2000 system (ESL: GETARCHARR, GETARCHVAL, GETARCHROW, GETARCHCOL, GETARCHSTRUCT, D2000 ObjApi: GetArchivData, D2000 VBApi: VBApiGetArchData, D2000 WorkBook) follows the rule that the archive object's value at any time (t) is given by (equals to) the last historical value at or before the given time (t). The data reading result is therefore given by the resampling and the begin (BT) and end (ET) time as follows:- resampling (step) = 0
The reading results are all the values, the time of which belongs to the interval <BT, ET> and one value before BT time, in case there is no value with a time exactly equal to BT time in the archive. - resampling (step) <> 0
The reading result is an array of values with timestamps continuously:
BT+0*step, BT+1*step, BT+2*step, ..., BT+N*step.
The number of values is given by the end ET of the time interval. If a record with the same timestamps does not exist in the archive database, the value of the array item will be equal to the last value before the specific required (however, the timestamp will be set accordingly).
- resampling (step) = 0
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If the Publish values option is checked, then the historical value publishes its last archived value in the a way, that depends on the object to archive, as follows:
- For a simple historical value - the object of the Historical value type gets the last value.
- When archiving a one-column historical value - the last archived values of individual items are filled into the relevant items of the column of a Structured variable type object defined by the Target object parameter.
- When archiving a structured historical value - the last archived values of individual items are filled into the relevant items of an object of a Structured variable type object , defined by the the Target object parameter.
Note: To ensure correct functionality of the Publish values feature for a one-column historical value (resp. structured historical value), the number of rows (in case of a structured historical value, also the number of columns) of the structured variable defined in the Target object parameter must be the same as the number of rows (columns) of the object defined by the parameter Object to archive.
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The input field is enabled if the Publish values option is checked. It allows you to define an object, that will contains values of the historical value. When archiving a simple historical value, the target object must not be defined. However, it must be defined for one-column historical value, and for structured historical value - the size of the target object must be the same as the size of the object defined by the parameter Object to archive.
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If the Publish values option is checked, then the historical value publishes its last archived value in the a way, that depends on the object defined by the parameter Historical value as follows:
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The input field is enabled if the Publish values option is checked. It allows you to define an object, that will contains values of the historical value. When archiving a a simple historical value, the target object must not be defined. However, it must be defined for one-column historical value and for structured historical value (see the Historical value parameter) - the size of the target object must be the same as the size of the object defined by the parameter Historical value.
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The option allows defining a mathematic expression containing objects of Historical value type (the Statement tab). The expression can not contain references to any other D2000 objects. Calculation of the expression provides values to be archived.
For example:
We have got two measurement points - two I/O tags, which are archived as historical values H.Flow1 and H.Flow2. If you need to archive the sum of both the flows, you can use two methods:
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Definition of a method to calculate a given expression - periodically or on value change. If the On value change option is selected, the expression will be recalculated when a value of at least one of the objects defined in the expression is changed.
An object of Historical value type defined in this way can be either simple or one-column historical value. If the object is a one-column historical value, the expression may also contain references to other structured or one-column historical values with the a row index of 0. During the calculation, the index is dynamically replaced by the current row number of the one-column historical value to recalculate. That allows defining the same expression for all column items.
Example of a structured expression: H.SourceColumn[0] + H.SourceStruct[0]^ColA
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- If the option is not checked, the parameter Structure size defines whether the historical value is simple or a one-column one.
If Structure size is not defined, the historical value is a simple one. If it is defined, the object is a one-column historical value - it is possible to define a column of a Structured variable type object, a column of a structured historical value, or a one-column historical value. The number of rows of the calculated one-column historical value is given by the number of rows of the objects defined in the parameter Structure size. - If the option is checked, the parameter Target column specifies whether the calculated historical value is simple or one-column.
If the Target column is not defined, the historical value will be a simple one that gets the last value.
If it is defined, the object will be a one-column historical value - it is possible to define a column of an object of a Structured variable type object. So, the number of rows of the historical value is given by the number of rows of the target columnstructured variable.
Archive size
Definition of archive size - see the Publish values parameter. The parameter will be visible only if the Publish values parameter is not checked.
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An object of Historical value type filled from a script can be used as a storage of values that are not generated by archiving the values of other D2000 system objects, statistical calculationcalculations, or by other expression calculations. Values can be only filled from an ESL script or manually from the the D2000 HI process.
Value storage can be simple, one-column, or structured. This is defined by the parameter Archive structure or Target structure (it depends on the parameter Publish values)
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The parameter will appears if the Publish values parameter is checked. It allows to define defining an object, that will contain values of the historical value - see the the Publish values parameter. If it is not defined, the historical value itself will contain the values.
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In the top part of the tab, an input edit field is placed. It serves for entering the expression, that determines the value of the historical value. The expression can contain functions, constants, and attributes - but objects must be of Historical value type only. The expression may also contain extended syntax.
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- Continuous - continuous (on the fly) calculation. Result values are calculated on the fly and they are automatically available (depending on the system load). A disadvantage of the method is a higher demand for computing power (especially for frequent changes of primary historical values that enter into the expression).
- On demand - the calculation is executed and the result is stored in the archive on demand. The demand can be generated by the CALCONDEMANDSTAT action or by the RECALC command ).
Note: historical values calculated "on-demand" should not have any depending on historical values calculated continuously because their results would be wrong. - On read - the calculation is executed as a result of a read request. An advantage of this method is that values are not stored in the database so they don't occupy any disk space. There is no possibility of re-calculation in case of writing delayed data into the archive. A disadvantage is the a necessity to read source data and calculate it for each read request. This method should be used for objects whose values are rarely needed.
Note: historical value calculated "on-read" should not have any depending historical values calculated continuously or "on-demand", because the result could be wrong in some cases (due to delayed data) or the calculation could be ineffective (multiple calculations of a single "on-read" object if it is used by several other historical values).
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| Function | Meaning |
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| None | No function. |
| Average * | Arithmetical average of all archive object values. |
| W-Average * | Weighted arithmetical average of all archive object values. |
| Integral | Time is integral to historical values. |
| Sum | Sum of archive object values. |
| Maximum | Maximum of archive object values. |
| Minimum | Minimum of archive object values. |
| Count | The number of archive object values. |
| Filter | Applying a filter for value storing in the statistical archive. |
| Increment | If the newer value is greater than the older one, then the difference between the values, otherwise the newer value (the function is useful to process counter values that overflow and start from zero again). |
| Delta | Delta between values. Parameter (Compare value) – the weight of impulse. The result will be the impulse multiplied by its weight. A weight of 1 will ensure standard behaviourbehavior. |
| EcoAvg | Average of the object values within the elapsed time period (Period parameter in Time parameters tab) according to the methodology based on flags of individual values entering the statistic. The same purpose is fulfilled by the function %EcoAveR, which is implemented for eval tags. |
| GT Time (>) | The function calculates the time, during which the value of the historical value was greater than the entered constant (Compare value). |
| GE Time (>=) | The function calculates the time, during which the value of the historical value was greater or equal to the entered constant (Compare value). |
| LT Time (<) | The function calculates the time, during which the value of the historical value was lower than the entered constant (Compare value). |
| LE Time (<=) | The function calculates the time, during which the value of the historical value was lower or equal to the entered constant (Compare value). |
| Maximum in the time interval | Obsolete - do not use! |
| Minimum in the time interval | Obsolete - do not use! |
| Number of local maximums | The number of local maximums in a given time interval. |
| Number of local minimums | The number of local minimums in a given time interval. |
| Sum of positive values | Sum of positive values of the historical value. |
| Sum of negative values | Sum of negative values of the historical value. |
| Average of positive values | Arithmetical average of positive values of the historical value. |
| Average of negative values | Arithmetical average of negative values of the historical value. |
| Sum of increments | Sum of increments for a given time interval. If the new value is less than the old value, the increment is 0. Parameter (Compare value) – the weight of impulse. The result will be the impulse multiplied by its weight. A weight of 1 will ensure standard behaviourbehavior. |
| Time slice** | Object value in given time moments. |
| Sample standard deviation | The function calculates the sample standard deviation of all values of the archive object. |
* For non-periodical values we recommend you to use using the W-Average (weighted average) function and , for periodical values the Average function for periodical valuesis appropriate.
** The function allows recalculation of the historical value if historical values archived primarily have been changed. In addition, the time of the end of the interval is always stored (this 'statistics' basically only resamples the source archive with the selected period).
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- Continuous - continuous (on the fly) calculation. Result values are calculated on the fly and they are automatically available (depending on the system load). A disadvantage of the method is a higher demand for computing power (especially for frequent changes of primary historical values that enter into the expression).
- On demand - the calculation is executed and the result is stored in the archive on demand. The demand can be generated by the CALCONDEMANDSTAT action or by the RECALC command ).
Note: historical values calculated "on-demand" should not have any depending on historical values calculated continuously because their results would be wrong. - On read - the calculation is executed as a result of a read request. An advantage of this method is that values are not stored in the database so they don't occupy any disk space. There is no possibility of re-calculation in case of writing delayed data into the archive. A disadvantage is the a necessity to read source data and calculate it for each read request. This method should be used for objects whose values are rarely needed.
Note: historical value calculated "on-read" should not have any depending historical values calculated continuously or "on-demand", because the result could be wrong in some cases (due to delayed data) or the calculation could be ineffective (multiple calculations of a single "on-read" object if it is used by several other historical values).
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This parameter (available from D2000 version 22) determines whether a value with an interval start/end time enters the calculation. The parameter is configurable for functions:
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