Working with a Blanket Object on a Schematic Sheet in Altium NEXUS

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Parent page: Schematic Objects

A rectangular shaped Blanket and a polygon shaped Blanket – each with an attached blanket Directive 
A rectangular shaped Blanket and a polygon shaped Blanket – each with an attached blanket Directive

Summary

A Blanket is a rectangular or polygon-shaped group Directive object that is placed over a collection of nets. A Directive (Parameter Set object) applied to the Blanket will then apply to all nets that the Blanket covers.

The Blanket applies to all nets that:

  • are completely within the area defined by the Blanket, or
  • have at least one connected end vertex of the wire / bus / harness under the Blanket, or
  • have a net label attached to the wire / bus / harness, and that net label is under the Blanket.

A Directive that is applied to the perimeter of the Blanket (Place » Directive), such as No ERC, Differential Pair or a specific Rule/Class Parameter Set, will apply to all nets registered by the Blanket object. Blankets may be disabled and hidden.

For detailed information about Directives see Specifying Design Requirements with Design Directives.

Availability

Blankets are available for placement in the schematic editor only. To place a Blanket:

  • Click Place » Directives » Blanket from the main menus.
  • Click the Blanket button () in the directives drop-down on the Active Bar located at the top of the workspace. Click and hold an Active Bar button to access other related commands. Once a command has been used, it will become the topmost item on that section of the Active Bar.
  • Right-click in the schematic editor then click Place » Directives » Blanket.

Placement

To place a rectangular Blanket:

  1. Launch the command as outlined above.
  2. Position the cursor then click or press Enter to effect placement of the top-left corner.
  3. Position the cursor then click or press Enter to effect placement of the bottom-right corner.
  4. Right-click or press Enter to complete placement.
  5. Continue placing further Blankets or right-click or press Esc to exit placement mode.

To place a polygonal-shaped Blanket:

  1. Launch the placement command.
  2. Position the cursor then click or press Enter to anchor the starting point for the Blanket.
  3. Position the cursor then click or press Enter to anchor a series of segments that define the shape of the Blanket.
  4. After placing the final segment, right-click or press Esc to complete placement. There is no need to 'close' the polygon as the software will automatically complete the shape by adding required segments to connecting the start point to the final segment placed.
  5. Continue placing further Blankets or right-click or press Esc to exit placement mode.

Additional actions that can be performed while the Blanket segments are being placed are:

  • Press the Tab key to pause the placement and access the Blanket mode of the Properties panel from where its line properties can be changed on-the-fly. Click the workspace pause button overlay () to resume placement.
  • Press the Spacebar to change the corner direction of an uncomitted segment corner.
  • Press Backspace to delete the previously committed segment when defining a polygonal shape for the Blanket. Successive use of Backspace will delete previous segments in order.
Placement mode is represented by a finer, dotted line. This is most useful when defining a polygonal-shaped Blanket. Use it to see how the overall shape of the Blanket will look before committing further segments. Complex/self-intersecting polygonal shapes are not supported – the software will prevent such shapes from being formed.

Graphical Editing

This method of editing allows you to select a placed Blanket object directly in the workspace and change its size, shape, or location graphically. When a Blanket object is selected, the following editing handles are available:

Selected rectangular and polygonal Blankets showing their graphic editing handles.Selected rectangular and polygonal Blankets showing their graphic editing handles.

Click and drag an editing handle at the center of a segment to move that edge of the Blanket.

For a rectangular Blanket, click and drag a corner editing handle to resize in both vertical and horizontal planes simultaneously.

Click anywhere on the outline of the Blanket away from editing handles and drag to reposition it. The Blanket can be rotated or flipped while dragging:

  • Press the Spacebar to rotate the Blanket counterclockwise about the cursor position. Shift+Spacebar rotates the Blanket clockwise about the cursor. Rotation is in increments of 90°.
  • Press the X or Y keys to flip the Blanket along the X-axis or Y-axis, relative to the cursor position.
Modification of a polygonal Blanket shape is prevented if it would result in a complex/self-intersecting shape.
If attempting to graphically modify an object that has its Locked property enabled, a dialog will appear asking for confirmation to proceed with the edit. If the Protect Locked Objects option is enabled on the Schematic – Graphical Editing page of the Preferences dialog, and the Locked option for that design object is enabled as well, then that object cannot be selected or graphically edited. Click the locked object to select it then disable the Locked property in the List panel or disable the Protect Locked Objects option to graphically edit the object.

Non-Graphical Editing

The following methods of non-graphical editing are available:

Via the Blanket Dialog or Properties Panel

Panel page: Blanket Properties

This method of editing uses the associated Blanket dialog mode and Properties panel mode to modify the properties of an blanket object.

     The Blanket dialog, on the left, and the Blanket mode of the Properties panel on the right

After placement, the Blanket dialog can be accessed by:

  • Double-clicking on the placed blanket object.
  • Placing the cursor over the blanket object, right-clicking then choosing Properties from the context menu.

During placement, the Blanket mode of the Properties panel can be accessed by pressing the Tab key. Once the blanket is placed, all options appear.

After placement, the Blankt mode of the Properties panel can be accessed in one of the following ways:

  • If the Properties panel is already active, by selecting the blanket object.
  • After selecting the blanket object, select the Properties panel from the Panels button in the bottom right section of the workspace, or by select View » Panels » Properties from the main menu.

The Blanket properties can be accessed prior to entering placement mode from the Schematic – Defaults page of the Preferences dialog. This allows the default properties for the Blanket object to be changed, which will be applied when placing subsequent Blankets.
If the Double Click Runs Interactive Properties option is disabled (default) on the Schematic - Graphical Editing page of the Preferences dialog, when the primitive is double-clicked or you right-click on a selected primitive then choose Properties, the dialog will open. When the Double Click Runs Interactive Properties option is enabled, the Properties panel will open. 
While the options are the same in the dialog and the panel, the order and placement of the options may differ slightly. 

Editing Multiple objects

The Properties panel supports multiple object editing, where the property settings that are identical in all currently selected objects may be modified. When multiples of the same object type are selected manually, via the Find Similar Objects dialog or through a Filter or List panel, a Properties panel field entry that is not shown as an asterisk (*) may be edited for all selected objects.

Via a List Panel

Panel pages: SCH List, SCH Filter

List panel displays design object types from one or more documents in tabular format, enabling quick inspection and modification of object attributes.

Used in conjunction with appropriate filtering – by selecting object types (using the panel's Include options), or by using the applicable Filter panel or the Find Similar Objects dialog – it enables the display of just those objects falling under the scope of the active filter. The properties for the listed objects may then be edited directly in the List panel.

Filtering Support

Two particularly useful keywords are available for use when targeting Blanket objects using logical query expressions. These complement the range of other keywords used to target a Blanket based on its properties.

  • Collapsed – the object is collapsed (also useful when targeting Compile Masks). This keyword can be found in the SCH Functions - Fields category when using the Query Helper.
  • IsBlanket – tests if the the object a Blanket. This keyword can be found in the SCH Functions - Object Type Checks category when using the Query Helper.

Create logical expressions for queries to target and return Blankets in your design as required. Some examples of logical query expressions targeting Blankets are:

IsBlanket And Collapsed – targets all Blanket objects that are currently collapsed.

IsBlanket And Not Collapsed – targets all Blanket objects that are currently not collapsed.

Disabling a Blanket

Once placed, Blankets can be temporarily disabled by clicking on the small triangle in the upper left (). Click once to disable and hide the Blanket; click again to re-enable it. This provides a convenient way of controlling the impact of the Blanket without needing to remove it completely from the design.

A Blanket can also be disabled by enabling the Collapsed and Disabled option in the Properties panel, or the Collapsed option when editing via the SCH List panel.

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