6 Attributes, Positioning and Orientation 93
6.1 Element Attributes 93
Every PDMS element has a fixed set of properties know as its attributes. Some attributes are common throughout the range of elements, some are applicable to many elements and some are unique to one type of element.
For some element attributes, appropriate values are set by the creation or modification of the element whilst others may be set or entered by the user via the User Interface.
For example, a cylinder primitive (CYLI) has the following attributes:
Attribute Description
Name The explicit element name or system generated element name. RefNo The unique database reference number.
Type The type of element. May be displayed as the abbreviated name.
Lock May be set to True (locked) or False (unlocked). If locked, the element may not be modified or deleted. Owner The name of the elements owning element.
Position
The position of the elements origin with respect to its owner’s origin. All primitives have an origin. The values of the coordinates are expressed in the current session units.
See Appendix A for details of PDMS Primitives.
Orientation The orientation of the components axis system with respect to its owner’s axis system.
See section 2.8 for an explanation of axis systems.
Level
PDMS can produce different representations of an item, depending on how it has been modelled and the representation levels used. The Level attribute is expressed as a range of levels; however, only one display level (for certain element types) may be displayed at one time.
Obstruction
The Obstruction attribute is used to declare whether an element may be considered solid or not. Obstruction values may be set to 2 (Hard), 1 (Soft) or 0 (No obstruction).
This attribute is used in clash detection purposes. Diameter The diameter of the cylinder in the current session units.
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Height The height of the cylinder in the current session units.Tmrref Template repeat reference. This is an advanced attribute applicable to primitives used with a repeat function in templates. RepCount Repeat Count. This is an advanced attribute applicable to primitives used with a repeat function in templates.
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Note that only the Diameter and Height attributes describe the geometry of the cylinder. Otherprimitives will have specific attributes that describe their geometry.
For a comprehensive list of element attributes, see the Data Model Reference Manual supplied with
PDMS.
6.1.1 Pseudo Attributes
In addition to the fixed set of attributes that all PDMS elements have, they also have a set of ‘derived’ attributes known as Pseudo Attributes. The number of pseudo attributes varies depending on the element type. Pseudo attributes may be queried and used in expressions, say in reports, in the same way as fixed attributes. Examples of pseudo attributes are:
Brweight – Branch weight (in kg) Clle – centreline length (of branch) Gcof – Gross centre of gravity (position) Ncof – Nett centre of gravity (position) Gwei - Gross weight (in kg)
Nwei – Nett weight (in kg)
Cutl – cut length (of structural profile) Tctl – true cut length (of structural profile)
For a comprehensive list of pseudo attributes, see the Data Model Reference Manual supplied with
PDMS.
6.1.2 User Defined Attributes
In addition to the standard element attributes, PDMS enables additional User Defined Attributes (UDA) to be assigned to one or more elements. The Lexicon module is used to create, modify and assign a UDA which is normally done by the System or Project Administrator.
A UDA is just like any other attribute but may be specific to the company or the particular project. The setting of the UDA is normally done manually by the user, although it may have a default value.
UDAs are prefixed by a colon which differentiates them from standard attributes, e.g.: • :Manufacturer - User Defined Attribute
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6.1.3 Querying and Displaying AttributesWhen working with PDMS there are numerous occasions when one or more attributes of a database element are required to be known, whether it be a standard attribute, a pseudo attribute or a UDA. PDMS provides two ways to query an element’s attributes.
6.1.3.1 The Attributes Form
Selecting Query>Attributes… from the main menu, or selecting the
Show Attributes option from the Design Explorer pop-up menu, displays the Attributes form for the CE.
The Attributes from is a re-sizeable and dockable form that displays, by default, the standard attribute data and any UDAs for the current element in a tabular grid.
The Track current element checkbox toggles the updating of the form when a new CE is selected.
Clicking in the grid with the right mouse button displays a pop-up menu with the following options:
• Attribute, Description and Data Type – these options toggle the display of the attribute name, attribute description and attribute data type as a column in the grid. A checkmark beside the option means that the option is displayed.
• Sort by Attribute – this option sorts the grid by attribute name in alpha-numeric order. Any UDAs are displayed first in the grid as they begin with a colon (:).
See section 6.1.2 for details of User Defined Attributes.
• Wrt World – this option toggles between giving data with respect to owner and world for position and orientation attributes.
See sections 6.2 and 6.3 respectively for an explanation of position and orientation attributes.
• P-Points – this option toggles the display of Ppoint data for elements that own Ppoints.
See section 9.1.3 for an explanation of Ppoints.
• Pseudo Atts – this option toggles the display of pseudo attributes.
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6.1.3.2 Querying Attributes using the Command WindowElement attributes may be queried via the Command Window. Entering Q ATT on the active line and pressing the Return key. Any attribute may be queried individually by enter Q followed by the full attribute name or its abbreviation, usually the first four characters, e.g. Q PURP has the same meaning as Q PURPOSE.
Attributes may also be grouped together, e.g. Q NAME PURP POS will display the attribute and its value on three separate lines.
UDAs appear in an element’s attribute list with the standard attributes if the Q ATT syntax is used. A pseudo attribute may be queried by entering Q <pseudo> where <pseudo> is the
attributes name.
Entering Q PSATTS lists all of pseudo attributes for the current element.
6.1.4 Modifying Attributes
Standard attributes and UDAs may be modified by selecting
Modify>Attributes… from the main menu to display the Modify Attributes form.
The content of the form depends on the selected element; however, all of the elements standard attributes and UDAs will be displayed.
By default, the CE button at the top of the form is active. When the form is opened the attributes of the CE are displayed. If a different element becomes the CE then clicking the CE button displays the new CE attributes. Checking the Track checkbox disables the CE button but automatically displays the CE attributes when a new CE is selected.
Un-checking the Track checkbox enables the CE button. The greyed out Write Access and Modify Allowed checkboxes indicate whether the user has write access to the CE and rights to modify its attributes.
The lower part of the form displays the setting of the current attribute highlighted in the list. The display changes depending on the attribute type. For example:
Highlighting a text type attribute displays a textbox where valid text may be entered, if the attribute is editable.
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On this form, the database reference number is displayed for un-named elements and not the systemgenerated name, e.g. CYLI 1 of EQUIPMENT /TANK1, are not displayed. Where an element has been explicitly named, the explicit name is displayed.
Highlighting a numeric type attribute displays a textbox where a valid value may be entered, if the attribute is editable.
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Highlighting a Boolean type attribute displays checkbox. If thecheckbox is checked the attribute value is true, if unchecked, the attribute value is false.
Having entered an appropriate and valid text, numeric value or checked/unchecked a textbox, clicking the
Apply button modifies the current attribute to the new value.
Non-editable attributes, generally those set by the system, e.g. Type and Owner, are displayed with their values greyed out, indicating that they are non-editable. The Apply button is also disabled. Where the attribute is a reference to another element a Navigate to Ref button is displayed. Clicking the Navigate to Ref button makes the referenced element the CE.
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The Referenced by: textbox is not used in the Design module.Attributes may also be modified using the Command Window, however, this is not recommended for inexperienced PDMS users.