Historical values - configuration dialog box

Editing of all objects in the D2000 CNF process is performed in the configuration dialog box, a specific part of which is common for all editable objects and another part depends on the type of edited object.

The configuration dialog box of processes consists of several parts (tabs) containing related parameters.

General properties
Groups
Archive
Statement
Time parameters
Conditions
Statistics
Filter

General properties

Description

A text string describing the historical value. Maximum: 128 characters.
Possibility to use the Dictionary (to open click the CTRL+L).

Status Text

Defines a status text of the historical value. The status text allows redefining individual values' identification for the historical value.

Transformation palette

Selection of an index to transformation palette. See the topic Transformation palette.

Value type

Selection of a value type of the historical value. The possible types are shown in the following table.

Note: Value type may be defined for the purpose of a historical value of "Calculate archived values by defined statement" type only.

Technical units

Technical units of the historical value. Maximum: 12 symbols. Possibility to use the Dictionary (to open click the CTRL+L).

Limits

Technological limits are effective only for historical values which are calculated by D2000 Archiv (evaluated and statistical historical values). There are 4 limits defined: VHL, HL, LL, and VLL. The limit can be defined either directly – by the value entered into the input field, or its value can be determined by a system object (dynamic limit) – the button right from the input field.

Values of the individual limits determine the state of the historical value according to its value. The relation value- limits gives six possible states.

As the limits can be dynamic (determined by the object value), a situation when the relation VLL<LL<HL<VHL is not valid (the limits crossing) can occur. The historical value is then in the Limit Problem state.

Note: Changing the value of the dynamic limit will not cause a new evaluation of limits and possibly a new value with a changed Limits attribute. The new value of the dynamic limit is taken into account only when archiving a new value.

Archive

Archive purpose

There are the following options:

• Archive object values - (primary archives) allows to archive values of D2000 system objects. Archiving can be either periodical or on value change.
• Calculate archived values by statistical function (statistical archives) - allows applying of a statistical function to a defined object of Historical value.
• Calculate archived values by defined statement (evaluated archives) - allows defining a custom formula on top of existing objects of Historical value type. The formula is defined in the Statement tab. The results of the calculation are again values, that will be archived.
• Fill archive from the script (Value storage) - values can be written either from an ESL script or manually from the process D2000 HI.
  Note: all types of Historical values (also primary, statistical, and evaluated) can be modified from an ESL script or manually from the process D2000 HI).

Archiving parameters

The part of the configuration dialog box contains the following options:

• Archive - if the option Archive is checked, then the defined object will be archived. If it is not checked, the object will not be archived (the archiving is disabled).
• Write Start/Stop - enables/disables automatic writing of START or STOP values.
• Depository - the option allows enabling/disabling of storing values of the historical value into the depository database.
• Depository segment - allows specifying the depository database segment the values to be stored in if the parameter Depository is checked. The parameter can be used for the Oracle platform with depository database segments enabled or for the PostgreSQL platform with depository database segments enabled.

ARCHIVE OBJECT VALUES

Ignore identical

Optimization of processing of old values of primary archives coming from communication (automatically or as a result of the GETOLDVAL command sent to the D2000 KOM process) or values of remote tags (as a result of TELL command GETOLDVAL sent to the D2000 Gateway Client process).
If the checkbox is checked, during the processing of the old value, the cache or archive database is queried whether the same value is already present there. If it exists, the value is discarded (and recalcs of statistical or calculated archived values that use this primary archive value are not performed either).
Note: Optimisation is useful e.g. for archiving of I/O tags from communication using the IEC62056-21:2002 File I/O protocol. Its communication files contain several historical values (which the D2000 KOM process sends as old values) and one new value for every I/O tag.

Object to archive

Definition of a D2000 system object, values of which are to be archived. The object may be defined either by typing its name into the input edit field or selecting from the list of objects. To open the list of objects, click the button right from the input field.

Object to archive or value source may be:

1. An object, the value of which is a simple type (Integer, Boolean, Real,...) - just one value is archived, therefore such archived object is called simple historical value.
2. An item of an object of Structured variable type - there is also just one value archived, therefore such archived object is called simple historical value, too.
3. A column of an object of Structured variable type (e.g. SV.Strct[0]^ColName) - there are archived all values of the column. Such an archived object is called a one-column historical value.
4. An entire object of Structured variable type (e.g. SV.Struct) - there are archived all values of the object. Such an archived object is called structured historical value.

Note: The above-described fact implies, that the object to archive directly specifies the type of historical value - simple, one-column, or structured historical one. 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.

Archiving method

When archiving the object values into the primary archive, it is possible to use the following method of archiving:

• Periodical  - writing values into the archive is periodical. The archiving process stores the archive object value into 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, time of which belong into 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.
• 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.
  
  Reading of values stored by using a filter by means of 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, 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).

Publish values

If the Publish values option is checked, then the historical value publishes its last archived value in the 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 a Structured variable type object defined by 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.

Target object

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.

CALCULATE ARCHIVED VALUES BY STATISTICAL FUNCTION

Historical value

Definition of an object of Historical value type, values of which are to be calculated. It can be:

• simple historical value - simple historical value, item of one-column historical value (e.g. H.ColArchiv[2]) or item of structured historical value (e.g. H.Struct[2]^ColName),
• one-column historical value - one-column historical value (e.g. H.ColArchiv) or column* of structured historical value (e.g. H.Struct[0]^ColName),
• structured historical value - structured historical value.

* The list of columns is given by the respective structure definition, which defines the structure of the historical value (e.g. H.Struct[2]^ColName).

Publish values

If the Publish values option is checked, then the historical value publishes its last archived value in the way, that depends on the object defined by the parameter Historical value as follows:

• For a simple historical value - the object of the Historical value type you are configuring gets the last value (unless the parameter Historical value is defined).
• When archiving a one-column historical value - the last archived values of individual items are published in 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 published in the relevant items of a Structured variable type object defined by the Target object parameter.

Note: To ensure correct functionality of the Publish values feature for a one-column historical value (structured HV) the number of rows (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 Historical value parameter.

Target object

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 (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.

CALCULATE ARCHIVED VALUES BY DEFINED STATEMENT

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:

1. Create an object of Eval tag type, that adds together the values of the I/O tags and then archive it.
2. Create an object of Historical value type with the expression of „H.Flow1 + H.Flow2“.

Both methods give the same result. A problem may occur when you need to modify e.g. the value of the object H.Flow1, which is already archived. If you used the first method, you must also manually change the value of the historical value. The second method automatically recalculates the expression and corrects the sum. So the D2000 Archive keeps the calculated (and also statistical) archives in synchronization with their source archives.

Calculation methods

Definition of a methods to calculate given expression - periodically or on value change. If the option On value change is selected, the expression will be recalculated when a value of at least one objects defined in the expression is changed.

Object of Historical value type defined in this way can be either simple or one-column historical value. If the object is one-column historical value, the expression may also contain the references to other structured or one-column historical values with the row index of 0. During the calculation, the index is dynamically replaced by current row number of the one-column historical value to recalculate. That allows to define the same expression for all column items.

Publish values

If the option Publish values is checked, than the historical value will publish its last value:

• If the option is not checked, the parameter Structure size defines whether the historical value is simple or one-column one.
  If Structure size is not defined, the historical value is a simple one. If it is defined, the object is one-column historical value - possible to define a column of a Structured variable type object, 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 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 - possible to define a column 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 column.

Archive size

Definition of archive size - see the parameter Publish values. The parameter will appear, if the parameter Publish values is not checked.

Target column

Definition of an object, that will contain values of the historical value - see the parameter Publish values. The parameter will appear, if the option Publish values is checked.

FILL ARCHIVE FROM SCRIPT (VALUE STORAGE)

Object of Historical value type filled from a script can be used as a storage of values which are not generated by archiving the values of other D2000 system object, statistical calculation or other expression calculation. Values can be only filled from an ESL script or manually from the process D2000 HI.

Value storage can be simple, one-column or structured one. This is given by the parameter Archive structure or Target structure (it depends on the parameter Publish values)

Inserted values are periodical

If the option is checked, you must define a period and offset (the tab Time parameters).

Publish values

Checking the option Publish values "renames" the parameter Archive structure to Target structure. The functionality of the parameter to define the archive is not changed, but it is not possible to define an object of Historical value type.
If the option Publish values is checked, the parameter Target structure defines whether the historical value is simple or structured one. If Target structure is not defined, the historical value is a simple one and gets the last value. If it is defined, the historical value is a structured one and will fill last value into the respective item of defined structured variable.

Archive playback

The parameter is enabled when the parameters Inserted values are periodical and Publish values are checked. If it is checked, the historical value will not publish its last value but the value that is valid according to the current time (e.g. from a ESL script, the feature allows to fill an object of Historical value type with values containing the future timestamps and the object "plays" them in real time).

Archive structure

The parameter appears when the parameter Publish values is not checked.

• If it is not defined, the historical value is a simple one.
• The historical value is a one-column one, if the parameter contains:
  • column of a structured historical value (e.g. H.Struct[0]^ColName)
  • one-column historical value (e.g. H.ColArchiv)
  • column of an object of Structured variable type (e.g.. SV.Struct[0]^ColName)
• The historical value is a structured one, if the parameter contains:
  • structured historical value
  • object of Structured variable type

Target structure

The parameter will appears if the parameter Publish values is checked. Allows to define an object, that will contains values of the historical value - see the parameter Publish values. If it is not defined, the historical value itself will contain the values.

Statement

In the top part of the tab, there is placed the input edit filed for entering the expression, that determines the value of the historical value. The expression can contains functions, constants, attributes but objects of Historical value type only. The expression may also contain the extended syntax.

Objects

The button allows to select an object of D2000 system. Selected object is to be inserted into the expression on the current cursor position.
Note: Expression can contain objects of Historical value type only.

Constants

The button allows to select a constant. Clicking it open the dialog box containing the list of predefined constant. Selected constant is to be inserted into the expression on the current cursor position.

Functions

The button allows to select a function. Clicking it opens the List of functions dialog box. Selected function is to be inserted into the expression on the current cursor position.

Attributes

The button allows to select an attribute. Clicking it open the dialog box containing the list of attributes. Selected attribute is to be inserted into the expression on the current cursor position.

Replace Invalid values with 0

If checked, all invalid values of the objects defined in the expression will be replaced with the value of 0. The feature can be used to prevent the expression from getting invalid value. There are converted just the values of input objects, invalid values of intermediate data are not converted. Values of inputs objects are converted as follows:

• Integer --> 0
• Real --> 0.0
• Relative time --> 0.0
• Boolean --> False

Other value types are not converted.

Maximum density of evaluation [s]

The parameter can be defined for the archive method Filter. It allows to restrict the number of evaluations of given expression so that the expression will be evaluated once within defined time. It is used especially in cases, when the values of the objects defined in the expression are often changed and calculating the expression is not required immediately. It is used especially in cases, when the values of the objects defined in the expression are often changed and calculating the expression is not required immediately.

Calculation

Method of the statement calculation:

• Continuous - continuous (on the fly) calculation. Result values are calculated on the fly and they are automatically available (in dependence on the system load). A disadvantage of the method is a higher demand on the computing power (especially for frequent changes of primary historical values).
• On demand - calculation is executed and result is stored to the archive on demand. The demand can be generated by the action CALCONDEMANDSTAT or the Tell command RECALC).
  Note: historical value calculated on demand should not have any depending historical values calculated continuously, because the result would be wrong.
• On read - 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 a necessity to read source data and calculate it for each read demand.
  Note: historical value calculated on read should not have any depending historical values calculated continuously or on demand, because the result could be wrong (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).

Time parameters

Archiving period

The parameters define the period (Hours : Minutes : Seconds) and the time offset within the period for the periodical primary and statistical archiving method (Hours : Minutes : Seconds).

History depth

Archiving time (Months : Days : Hours). The parameter determines the archiving time depth. It is the minimal time period, during which the data will be stored in the on-line archive. The older data are being erased from the archive.

The maximum history depth is 800 months (approximately 66 years).

Stored time

For periodical data archiving, it is defined, what time data with the value for the given period will be stored into the archive. The time data can present the begin time - Period begin option or the end time of the interval (period) - Period end option.

Note: For archives filled from script, this setting does not directly affect anything - the data has a time stamp with which it was stored from the script. It however affects the calculation of statistics and whether statistics are calculated from the value at the edge of the interval.

Conditions

Defining the conditions for the start and interruption of the archiving is provided by the mechanism of the object archiving dynamical control depending on values or states of others objects in the system. Both conditions need not have to be defined. If not defined, the archiving will be started immediately after the start and initialisation of the process Archive.

Start condition

Defining the condition causing the start of the given historical value.

The object representing the archiving start condition may be defined by several ways:

• writing the object in to the input field,
• selecting the object from the list of objects - the list opened after clicking the button right from the input field,
• creating a new object - Create new object button.

Also, it is necessary to define, for what state of the given object is the condition valid. In the list under the object entry field, there are displayed possible object value states. This list is different for various  kinds of types of objects. The archiving start condition will be valid, if the object is in the chosen state. If the option Inverse function is enabled, the condition is valid, if the object is in status other than the chosen state.

Stop condition

Defining the condition that causes stopping the archiving of the given historical value.

The object representing the archiving stop condition may be defined by several ways:

• writing the object name into the input field,
• selecting the object from the list of objects - the list is opened by clicking the button right from the input field,
• creating a new object - Create new object button.

Also, it is necessary to define, for what state of the given object is the condition valid. In the list under the object entry field, there are displayed possible object value states. This list is different for various  kinds of types of objects. The archiving stop condition will be valid, if the object is in the chosen state. If the option Inverse function is enabled, the condition is valid, if the object is in status other than the chosen state.

Statistics

Statistical function

When archiving into the statistical archive it is possible to use these implemented functions.

* For non-periodical values we recommend you to use the W-Average (weighted average) function and the Average function for periodical values.
** The function allows recalculation of the historical value if historical values archived primarily have been changed.

The difference among the functions INCREMENT, DELTA and SUM OF INCREMENTS is shown in the following figures.

In the first case, all three functions are equal to 5 (10-5)

In the second case

• DELTA = 5-10 = -5
• INCREMENT = 5 (because 5 <10)
• ADDITIONAL AMOUNT = 0 (because 5 <10)

In the third case

• DELTA = (10 - 5) + (2 - 10) + (10 - 2) = 5
• INCREMENT = (10-5) + 2 (because 5 <10) + (10-2) = 15
• ADDITIONAL AMOUNT = (10-5) + 0 (because 5 <10) + (10 - 2) = 13

Calculation

Statistics calculation method:

• Continuous - continuous (on the fly) calculation. Result values are calculated on the fly and they are automatically available (in dependence on the system load). A disadvantage of the method is a higher demand on the computing power (especially for frequent changes of primary historical values).
• On demand - calculation is executed and result is stored to the archive on demand. The demand can be generated by the action CALCONDEMANDSTAT or the Tell command RECALC). Note: historical value calculated on demand should not have any depending historical values calculated continuously, because the result would be wrong.
• On read - calculation is executed as a result of a read request. An advantage of the method is that values are not stored in the database so they don't occupy any disk space. There is no chance of wrong calculation in case of writing delayed data into the archive. A disadvantage is a necessity to read source data and calculate it for each read demand.
  Note: historical value calculated on read should not have any depending historical values calculated continuously or on demand, because the result could be wrong (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).

Validation criteria

The value of the parameter Validation criteria defines the value percentage in the primary archive (used fro the calculation of values stored into the statistical archive) that has to be valid, in order to acquire a valid result. If there were less valid values than stated in Validity criteria, the result will be Weak_Value.

Time interval for statistical calculation

Statistical time period defines the time interval, the set of historical values, that will be processed by the particular statistical function. By default, the interval is equal with the archiving period. If it is necessary to enter different period, check the option Time interval different from archiving period and enter required period into the parameter Interval. The time period must be greater than 0 [s].

Compare value

A parameter for the functions GT Time (>), GE Time (>=), LT Time (<), LE Time (<=).

Integral time units

A parameter for the function INTEGRAL:

• Hours - hour integral
• Minutes - minute integral
• Seconds - second integral

Filter

The system allows to archive considerable value changes of the archive object. This archiving method represents defining of three deadband levels, that are possible to set various values of significant changes.

Values of filtering:

• High limit - defining the high limit for filtering.
• Low limit - defining the low limit for filtering.
• Above limit - defines a significant change of the archive object above the high limit.
• In limit - defines a significant change of the archive object within the the lower and high limits.
• Below limit - defines a significant change of the archive object below the low limit.