Special Design Data Property names in scope of a DDSE

Model Reference Manual

Design Templates : Application Data Areas : Special Design Data Property names in scope of a DDSE

Special Design Data Property names in scope of a DDSE

Each of the Local Design Data pseudo attributes DEPL, LDPR, DEPR, DEPD and LFDP take a qualifier that is the key to a particular design data element (the DKEY of the DDAT). Special values of this key are used to query values within the DDAT and VVALUE elements:


VALI:	for returning evaluation of the VALIDV attribute of a VVALUE
VALR:	for returning the evaluation of a VALRUL attribute of a VVALUE
VVAL:	for returning a VALIDV/ALUE result with a true VALRULE
DDAT:	for returning the value of the local DDAT (either a DPROPerty or else a DDEFAUlt without knowing its DKEY


element special key word	DDAT	VVALUE
VALR	ERROR, no VALRUL attribute	result of evaluated VALRUL attribute
VALI	ERROR, no VALIDV attribute	result of evaluated VALIDV attribute
VVAL	returns VVAL result of first VVALUE element that does not ERROR,	returns result of evaluated VALIDV if VALRUL evaluates TRUE, else ERROR
DDAT	returns the same value as would be returned using the DKEY of the DDAT. (Either the DPROPerty or DDEFAUlt value). This is a convenient way of obtaining this value without knowing the DKEY	Returns the same value as the DDAT property of the owning DDAT without having to know the actual DKEY value to use.

All of these properties will error if queried at the DDSE element or above.

If the Design Data set actually has a data element that has a property with one of these name keys (they are not reserved in anyway) then the use of the key will operate normally on the DDSE or its owner, and as listed in the table above on a DDAT or VVALUE.

Use of the VVAL key on a particular DDAT will return the first suitable value from a set of many values. This is similar to choosing from a set of values according to some criteria. It is possible to use this as an alternative to the IFTRUE expression, which can, for example when used iteratively, select a set of possible choices depending on a particular criterion. The IFTRUE expressions will increase the expression length with the possibility of exceeding the maximum length of the text attribute. Use of VVAL key will not do this.

The VVALUEs owned by a DDAT DO NOT modify the return values of design data properties when queried by their owners.

It should be noted that if the DPROPerty of a DDAT is inconsistent with the set of VVALUEs that it owns, this will NOT raise an exception or error when querying it directly using its DKEY. It is up to the application using these data values to decide whether to accept the value of a DPROPerty whenever it conflicts with valid values, or maximum or minimum values, or a tolerance. To do otherwise would risk the integrity of existing user and system applications.

1974 to current year. AVEVA Solutions Limited and its subsidiaries. All rights reserved.