Restricting Property Values for use in a Design

When we set the properties for the kickplate, in the earlier steps of the exercise, we did not impose any restrictions on the dimensions which a designer could apply when using the template. The design parameters representing the kickplate’s length, width, height and wall thickness could be set to any values.

As a template designer, you can restrict the values which a user can set in one of two ways. These are controlled by the Range/Values option near the center of the Define Template Properties form, and act as follows:

• Range lets you specify minimum and maximum values for a design parameter. These are stored in the MinMax attribute of the Design Data (DDAT) element corresponding to that property. When used in a design, only values in the specified range will be accepted.

• Values lets you specify a list of discrete values for a design parameter. These are stored as the ValidV attributes of Valid Value (VVALUE) elements owned by the DDAT corresponding to that property. When used in a design, only these values will be available for selection from a list.

We will use both of these methods in the following steps.

Exercise continues:

1. We will set the first property to represent the outside diameter of the vessel body. Enter the following data:

   Description	Diameter of Vessel
   Key	DIAM (it is good practice to use common keys in all equipment and sub-equipment templates to make their rules consistent)
   Definition/No	Design Parameter 1
   Data Type	Distance
   Default	1000 (making this larger than the original equipment diameter of 400 lets you see the change take effect in the 3D View)

   We will restrict the user’s choice of diameter values to some explicit dimensions. To do so, select the Values option and click the button to the right of that row of gadgets. The resulting Set Valid Values form contains a text-pane into which you can type your list of valid diameters. Enter the following values:

   400 500 1000 1200 2000 4000

   either separated by spaces or on separate lines. Note that this list should include the default value (in this case 1000), otherwise a designer cannot easily reset this if they have changed it. Click OK to store the valid values data, then click the Include button on the Define Template Properties form to add the property into the Currently Defined Properties list. Navigate to the TMPL /Vessel-Main-Body in the Design Explorer and check that its DDSE owns a DDAT which owns six VVALUEs (one for each valid diameter).

   

2. The next property will represent the length of the vessel body. Enter the following data:

   Description	Length of Vessel
   Key	LENG
   Definition/No	Design Parameter 2
   Data Type	Distance
   Default	2000

   For this property we will restrict the user’s choice of length to any value between specified limits. To do so, select the Range option and enter 1000 and 4000 in the From and To fields.

   Note: Changing to Range automatically clears any Values data stored by the Set Valid Values form; otherwise this data remains in force until you delete it. Take care not to set new properties to the current valid values data unintentionally.

   Include the new property in the Currently Defined Properties list.

3. Create a third property representing the wall thickness of the vessel body. Enter the following data:

   Description	Thickness of Vessel
   Key	THKN
   Definition/No	Design Parameter 3
   Data Type	Distance
   Default	20

   This property will have no restrictions on its values, so keep the Range option selected and delete the entries from the From and To fields.

4. Create a fourth property representing the height of the vessel’s centerline above the floor (the latter level will correspond to the template’s origin; see diagram at the beginning of this chapter). Enter the following data:

   Description	Centerline Height
   Key	CHEI
   Definition/No	Design Parameter 4
   Data Type	Distance
   Default	600

   This property will have no restrictions on its values, so leave the Range option as it is.