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CALCARCHEXPR action
Function
The action performs a calculation of specific archival expression over archival values. Archival values are presented through the names of archival objects in the expression.
Declaration
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CALCARCHEXPR archExprIdent_Txt, btIdent_TimA, etIdent_TimA, stepIdent_Int, _ignoreInvalid_Bool, _locVarColValueIdent_Rec, statusIdent_Int[, archivInstance_Int] |
Parameters
| archExprIdent_Txt | in | Value identifier of Text type containing the expression. |
| btIdent_TimA | in | Identifier of AbsTime type - interval beginning. |
| etIdent_TimA | in | Identifier of AbsTime type - interval end. |
| stepIdent_Int | in | Identifier of Int type - time step [s]. |
| _ignoreInvalid_Bool | in | Identifier of Bool type - invalid values in expression will be replaced by 0. |
| _locVarColValueIdent_Rec | out | Reference to a local variable column of RECORD type - final values. |
| statusIdent_Int | out | Identifier of Int type - the success of calculation. |
| archivInstance_Int | in | Optional identifier of Int type - identification of archive instance. If the parameter is not defined, the value 0 will replace it. |
Description
The action performs a calculation of specific archival expression over archival values. Archival values are presented through the names of archival objects in the expression.
The rules of this calculation are identical to the calculation rules mentioned in definition of calculated archival object.
If a structured archive is used in an expression, a zero [0] number of row cannot be used.
The calculation is performed for entered time period <btIdent_TimA, etIdent_TimA>.
If parameter stepIdent_Int
= 0 - it means the calculation for change => each change some of the source data (archived) causes the entered expression recount and relevant value will be in result. ≠ 0 - it means the periodic calculation => the entered expression is evaluated in periods btIdent_TimA, btIdent_TimA+1*stepIdent_Int, btIdent_TimA+2*stepIdent_Int .... Resultant value array is written into entered column of local structured variable _locVarColValueIdent_Rec (variable can be dimensioned again).
The rules of this calculation are identical to the calculation rules mentioned in definition of calculated archival object.
If a structured archive is used in an expression, a zero [0] number of row cannot be used.
The calculation is performed for entered time period <btIdent_TimA, etIdent_TimA>.
If parameter stepIdent_Int
= 0 - it means the calculation for change => each change some of the source data (archived) causes the entered expression recount and relevant value will be in result. ≠ 0 - it means the periodic calculation => the entered expression is evaluated in periods btIdent_TimA, btIdent_TimA+1*stepIdent_Int, btIdent_TimA+2*stepIdent_Int .... Resultant value array is written into entered column of local structured variable _locVarColValueIdent_Rec (variable can be dimensioned again).
Note
1. The expression must contain the name at least one of archive value.
2. If the expression contains several archive values, they all must have one parent in terms of DODM.
2. If the expression contains several archive values, they all must have one parent in terms of DODM.
Example
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TIME _bt, _et
INT _step
INT _retCode
TEXT _expr
TEXT _err
BOOL _bIgnoreInvalid
RECORD NOALIAS (SD.Data) _data
_bt := %StrToTime("00:00:00 01-01-2008")
_et := %StrToTime("00:00:00 02-01-2008")
_step := 1
_bIgnoreInvalid := @TRUE
_expr := "H.a + H.GetArchRowCol_Ref[2]^I2 + H.GetArchRowCol_Ref_Col_I1[2]"
CALCARCHEXPR _expr, _bt, _et, _step, _bIgnoreInvalid, _data^Value, _retCode
IF _retCode = _ERR_NO_ERROR THEN
; processing of result
ELSE
_err := _ERR_MSG ; extended error description
ENDIF |
Owing to the expression parsing works during system running (not during configuration) and if any errors occur, it is possible to obtain their detailed description as value of predefined local variable of Text type _ERR_MSG.
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