Parent page: Schematic Objects
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 sub-circuits in your PCB Projects. They allow for a more complex design within the same schematic design space, which increases the readability of designs and builds potential for reuse.
Signal harnesses are available for placement in the Schematic Editor in one of the following ways:
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:
Additional actions that can be performed during placement while the signal harness is still floating on the cursor and before its first corner is anchored are:
When placing a signal harness there are three 'manual' placement modes, two 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:
Schematics have a definable electrical grid that makes it easy to define electrical connections between objects. While placing a Signal Harness, when the Signal Harness falls within the electrical grid range of another electrical object, the cursor will snap to the fixed object and a Hot Spot (blue 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 electrical grid can be defined in the General region of the Properties panel in Document Options mode (accessed when no objects are selected in the design space). It is recommended that you set the electrical grid to be slightly smaller than the current snap grid, or it becomes difficult to position electrical objects one snap grid apart.
This method of editing allows you to select a placed signal harness object directly in the design space and change its size and/or shape graphically.
When a signal harness object is selected, the following editing handles are available:
With the signal harness selected, click on a segment to individually select that segment. This harness 'sub-selection' is distinguished by the associated editing handles becoming red in color.
The associated vertices for the segment can then be edited directly using the SCH List panel and any changes will appear immediately on the schematic.
The following methods of non-graphical editing are available:
Properties page: Signal Harness Properties
This method of editing uses the associated Signal Harness dialog and the Properties panel mode to modify the properties of a signal harness object.
After placement, the Signal Harness dialog can be accessed by:
During placement, the Signal Harness mode of the Properties panel can be accessed by pressing the Tab key. Once the signal harness is placed, all options appear.
After placement, the Signal Harness mode of the Properties panel can be accessed in one of the following ways:
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 SCH Filter or SCH List panel, a Properties panel field entry that is not shown as an asterisk (
*) may be edited for all selected objects.
The SCH List panel allows you to display design objects from one or more documents in tabular format, enabling quick inspection and modification of object attributes. Used in conjunction with appropriate filtering - by using the SCH Filter panel, or the Find Similar Objects dialog - it enables the display of 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.
A T-junction in a signal harness is automatically connected by a junction (Compiler-Generated Junction). 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 on each side of the junction. With this option disabled, the signal harness segment will remain unbroken at the junction.
The term Signal Harness is used to describe both the bus-like line that runs between a Harness Connector and a Harness Port and also the overall connectivity system created by these connected harness objects.
To learn more, refer to Working with Signal Harnesses.