Datum Dimension

Parent page: PCB Dialogs

Summary

A datum dimension is a group design object. It allows for the dimensioning of a linear distance of a collection of objects, relative to a single reference object. The first object chosen is the 'base'. All subsequent objects are relative to this first object. The dimension value in each case is therefore the distance between each reference object and the 'base', measured in the default units. The references may be tracks, arcs, pads, vias, text, fills, polygons or components.

Access

The Datum Dimension dialog can be accessed prior to entering placement mode, from the PCB Editor - Defaults page of the Preferences dialog (DXP >> Preferences). This allows you to change the default properties for the object, which will be applied when placing subsequent Objects.

During placement, the dialog can be accessed by pressing the Tab key.

After placement, the dialog can be accessed in the following ways:

• Double-clicking on the placed dimension object.
• Placing the cursor over the dimension object, right-clicking and choosing Properties from the context menu.
• Run command Edit >> Change, then click an existing object.

Options/Controls

• Text Gap - Specify the distance between the arrow and the display text.
• Pick Gap - Specify the gap between the objects and the extension line of Dimension object.
• Roatation - Specify the rotation angle of dimension object.
• Text Height - Specify the height of the display text.
• Text Width - Specify the line width of the display text.
• Extension Width - Specify the width of extension line.

Properties

• •  Layer - Specify the layer on which the Dimension object is placed. The drop-down list will list out all stack-up layers in current active PCB document.

  • Format - The display format of the dimension text, the display unit depends on Unit option setting. Assume the exact dimension value is 794.44 mil, there are four display modes available: None, 794.44, 794.44 mil, 794.44 (mil).

  • Position - Specify the position of dimension text. There are multiple choices in drop-down list:

    • Aligned: Locate the text in align with the direction of  the extension line.
    • Unidirectional: Change the text direction as horizontal.
    • Manual: Manually locate the text to any preferred position.
       

  • Locked - Check this box to lock Dimension object. If you attempt to graphically modify the dimension object that has its Locked property enabled, a dialog will appear asking for confirmation to proceed with the edit.

  • Font - Choose Font for the display text. There are two Font types available: True Type, Stroke.

  • Unit - Specify unit for dimension value. Two options are available: Mils, Millimeters, Inches, Centimeters, Automatic.

  • Precision - Specify precision for dimension value. 

  • Prefix - Add a prefix for dimension value text. 

  • Suffix - Add a suffix for dimension value text.  

  • Sample - A display sample of the dimension value, based on related option settings in Properties region.

Select Stroke / TrueType Font

Depending on whether TrueType or Stroke fonts have been selected, a number of different options will be available.

• • Font Name: Stroke 

For Stroke Fonts, the Font Name drop down list will offer Default, Sans Serif, and Serif fonts for selection. The Default style is a simple vector font which supports pen plotting and vector photo plotting. The Sans Serif and Serif fonts are more complex. The provide a more natural looking text display but they will slow down vector output generation such as Gerber. Stroke-based fonts are built into the software and cannot be changed. All three fonts have the full IBM extended ASCII character set that supports English and other European languages.

• • Font Name: TrueType

If TrueType Fonts are selected, the Font Name drop down list will be populated with the names of the True/Open Type fonts found in the \Windows\Fonts folder.
Note that the list will only include entries for detected (and uniquely named) root fonts. For example, Arial and Arial Black will be listed but Arial Bold, Arial Bold Italic, etc will not. Use the Bold and Italic options to add emphasis to the text. This feature also offers full Unicode support.