Altium Designer Documentation


Created: June 9, 2022 | Updated: June 9, 2022

Parent page: Schematic Commands

The following pre-packaged resource, derived from this base command, is available:

Applied Parameters: None


This command is used to place a Signal Harness object onto the active document. A Signal Harness is an electrical design primitive. It is an abstract connection that enables the logical grouping of different signals including buses, wires and other signal harnesses, for increased flexibility and streamlined design. Signal Harnesses allow for the creation and manipulation of higher level abstract connections between subcircuits in your PCB Projects. They allow for a more complex design within the same schematic workspace, thereby increasing readability of designs and building potential for re-use.

For detailed information about this object type, see Signal Harness.


Signal harnesses are available for placement in the Schematic Editor only, by:

  • Choosing Place » Harness » Signal Harness from the Schematic Editor main menu.
  • Locating and using the Signal Harness command () on the Active Bar.
If the command has been recently used from the Active Bar, it will become the active/visible button. Where other commands are available, this is indicated by a triangle at the bottom-right corner of the button. Click and hold on the active button to access a menu of all associated commands for that grouping.
  • Clicking the  button on the Wiring toolbar.
  • Right-clicking in the workspace and choosing Place » Harness » Signal Harness from the context menu.


After launching the command, the cursor will change to a cross-hair and you will enter signal harness placement mode. Placement is made by performing the following sequence of actions:

  1. Click or press Enter to anchor the starting point for the signal harness.
  2. Position the cursor and click or press Enter to anchor a series of vertex points that define the shape of the signal harness.
  3. After placing the final vertex point, right-click or press Esc to complete placement of the signal harness.
  4. Continue placing further signal harness objects, or right-click or press Esc to exit placement mode.
  5. Use the Backspace or Delete keys to remove the last harness segment placed.
While placing the signal harness, press the Tab key to access the Properties panel, from where properties for the signal harness can be changed on-the-fly. Pressing Tab pauses placement, allowing you to interact with the panel (or other area of the software) directly. To resume, click the pause symbol that appears over the workspace.

Placement Modes

When placing a signal harness there are 3 'manual' placement modes, 2 of which have Start and End sub-modes. The mode specifies how corners are created when placing signal harnesses and the angles at which signal harnesses can be placed. During placement:

  • Press Shift+Spacebar to cycle through the 90 Degree, 45 Degree and Any Angle modes.
  • While in the 90 Degree or 45 Degree mode (known as true orthogonal modes), press Spacebar to cycle between the Start and End sub-modes.
  • During placement, the current placement mode is displayed in the Status bar. You can change modes at any time during signal harness placement.
  • In modes other than Any Angle, the line segment attached to the cursor is a look ahead segment. The segment you are actually placing precedes this look ahead segment.
There is also an Auto Wire mode, which can be used to route quickly from the previous segment end, to the point where the cursor is clicked, using the Point to Point Router. The path of the route will be the most efficient possible, while avoiding existing placed objects on the sheet.

Guided Wiring

Schematics have a definable 'electrical grid' that makes it easy to define electrical connections between objects. As you are placing a signal harness, when the harness falls within a defined range of attraction of another electrical object the cursor will snap to the fixed object and a Hot Spot (red cross) will appear. The Hot Spot guides you to where a valid connection can be made and automatically snaps the cursor to electrical connection points.

The range of attraction, or distance within which an object will electrically snap to the hotspot of another electrical object, can be defined using the Snap Distance field, in the General section of the Properties panel (when no objects are selected on the sheet). It is recommended that you set this 'object snapping' range to be slightly smaller than the current snap grid, or it becomes difficult to position electrical objects one snap grid apart. Object snapping can be toggled on or off using the Shift+E keyboard shortcut, or by enabling/disabling the Snap option (above the Snap Distance field in the Properties panel).


  1. A T-junction in a signal harness is automatically connected by a junction (Compiler-Generated Juntion). If the Break Wires At Autojunctions option is enabled, on the Schematic - General page of the Preferences dialog, an existing signal harness segment will be broken into two at the point where an autojunction is inserted. For example, when making a T-Junction, the perpendicular signal harness segment will be broken into two segments, one each side of the junction. With this option disabled, the signal harness segment will remain unbroken at the junction.
  2. For information on how a placed signal harness object can be modified graphically, directly in the workspace, see Graphical Editing.
  3. While attributes can be modified during placement (Tab to bring up the Properties panel), bear in mind that these will become the default settings for further placement unless the Permanent option on the Schematic - Defaults page of the Preferences dialog is enabled. When this option is enabled, changes made will affect only the object being placed and subsequent objects placed during the same placement session.


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