Parent Page: Objects

The Sheet Symbol Designator.

Summary

The sheet symbol designator is a non-electrical child object of an electrical design primitive. It is used to provide a sheet symbol with a meaningful name that will distinguish it from other sheet symbols placed on the same schematic sheet. Typically the name will reflect the overall function of the schematic sub-sheet that the symbol represents.

Availability and Placement

The sheet symbol designator is automatically placed when the parent sheet symbol object is placed. As such, it is not a design object that can be accessed and placed by the user.

Non-Graphical Editing

The following three methods of non-graphical editing are available:

...via an associtated properties dialog

This method of editing uses the following dialog to modify the properties of a sheet symbol designator object, independently of the parent sheet symbol object.

The Sheet Symbol Designator dialog.

The Sheet Symbol Designator dialog can be accessed prior to entering sheet symbol placement mode, from the Schematic - Default Primitives page of the Preferences dialog (Tools » Schematic Preferences). This allows you to change the default properties for the sheet symbol designator object, which will be applied when placing subsequent sheet symbols.
After placement, the Sheet Symbol Designator dialog can be accessed in one of the following ways:

• double-clicking on the designator field of the placed sheet symbol object
• selecting the designator field of the sheet symbol object and choosing Properties from the right-click pop-up menu
• choosing the Change command from the Edit menu and then clicking once over the designator field of the placed sheet symbol object.

...via the SCH Inspector panel

The SCH Inspector panel enables you to interrogate and edit the properties of one or more design objects in the active document. Used in conjunction with appropriate filtering, the panel can be used to make changes to multiple objects of the same kind, from one convenient location.

...via the SCH List panel

The SCH List panel allows you to display design objects from one or more documents in tabular format, enabling you to quickly inspect and modify object attributes. When used in conjunction with the SCH Filter panel, it enables you to display just those objects falling under the scope of the active filter - allowing you to target and edit multiple design objects with greater accuracy and efficiency.

Graphical editing

This method of editing allows you to select a sheet symbol designator object directly in the workspace and change its location graphically. Sheet symbol designators can only be adjusted with respect to their size by changing the size of the font used (accessed through the Sheet Symbol Designator dialog). As such, editing handles are not available when the sheet symbol designator object is selected:

A selected designator.

Click anywhere inside the dashed box and drag to reposition the sheet symbol designator object as required. The object can be rotated or flipped while dragging:

• Press the Spacebar to rotate the designator. Rotation is anti-clockwise and in steps of 90°.
• Press the X or Y keys to flip the designator along the X-axis or Y-axis respectively.
  If the Enable In-Place Editing option is enabled on the Schematic - General page of the Preferences dialog (Tools » Schematic Preferences), you will be able to edit the name for the sheet symbol designator directly in the workspace. Select the designator and then click once to invoke the feature. Type the new name as required and then click away from the designator field or press Enter to effect the change.

Notes

1. By using sheet symbol instantiation, multiple channels on the same sub-sheet can be referenced from a single sheet symbol. The syntax used involves the use of the Repeat keyword in the sheet symbol's Designator field and takes the form:
   Repeat(SheetSymbolDesignator, FirstInstance, LastInstance),
   
   using Repeat keyword.
   where SheetSymbolDesignator is the base name for the sheet symbol and FirstInstance and LastInstance together define the number of channels to be instantiated. The FirstInstance parameter should start at 1 or greater. The example image below illustrates the use of the Repeat keyword to instantiate 8 input channels for an audio mixer.
   When the project is built, the Compiler instantiates the channel the required number of times as it builds the internal compiled model, using a chosen annotation scheme to uniquely identify each component in each channel. The channel sub-sheet is not duplicated. Instead, once compiled, a separate tab appears at the bottom of the sub-sheet document in the main design window, for each channel on that sheet, as shown in the example image below.
   
   After compilation of a sheet symbol with a designator of Repeat-keyword.