Altium NEXUS Documentation

Working with an Accordion Object on a PCB in Altium NEXUS

Created: March 20, 2019 | Updated: March 20, 2019
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Parent page: PCB Objects

Accordion objects are added to increase the length of a route, the Net Length Gauge indicates the progress towards achieving the required target length.


The accordion object is a system-created group object. The accordion object is created by the software during interactive length tuning to increase the overall length of a route. The software builds the accordion shaped section of routing from tracks and/or arcs in accordance with the properties defined in the Accordion mode of the Properties panel. Because the accordion object is a group object, a placed accordion can be interactively reshaped if required.

Accordion shaped sections of routing are also created by the Interactive Diff Pair Length Tuning command and also during interactive routing if the Add Accordion option has been enabled. These shapes are not true accordion objects, after they are placed they are simply a collection of tracks and/or arcs, which can be individually selected. The information on this page does not apply to this older style of accordion routing. It is expected that these accordion shapes will also become true accordions in a future update of Altium NEXUS.


The accordion object is placed automatically in the PCB editor when the Interactive Length Tuning command is being used and the route length is shorter than the length specified for that net.

The route length requirement is specified by:

  • An applicable Length design rule.
  • An applicable Matched Length design rule.
  • A user-defined length, specified in the Accordion mode of the Properties panel.

All of the properties of an accordion are configured in the Accordion mode of the Properties panel. If the panel is not visible, click the  button to enable it or use the View » Panels sub-menu.


Accordions are placed when the Interactive Length Tuning command is run, and the route length needs to be increased.

After launching the PCB editor's Route » Interactive Length Tuning command, the cursor will change to a  cross-hair and you will enter length tuning (Accordion placement) mode. Placement is made by performing the following sequence of actions:

  1. Click on the routed net that needs its length to be increased.
  2. Move the cursor along the route in the direction that the accordion is to be added as shown in the animation above. An accordion will appear and continue to grow as the cursor moves. The accordion properties (length, style, amplitude, and gap) will be in accordance with the current settings defined in the Accordion mode of the Properties panel (more on this below). The amplitude of the accordion is automatically decreased to avoid existing routing and component objects as shown in the image at the top of this page.
  3. During placement, the cursor can move away from the existing route by up to the current Max Amplitude distance specified in the Properties panel. If the cursor moves further than this, the accordion currently being placed will disappear. Move the cursor back towards the existing route to restore the accordion being placed.
  4. The accordion will stop growing when the required overall route length is achieved, if the Clip to Target Length option is enabled in the Properties panel. Click to complete placement of the accordion.
  5. Continue tuning other route lengths (placing further accordions) or right-click or press Esc to exit length tuning mode.

Additional actions that can be performed during placement include:

  • Press the Tab key to pause placement and access the Accordion mode of the Properties panel from where its properties can be changed on-the-fly. Click the workspace pause button overlay () to resume placement.
  • The properties of the accordion can also be interactively adjusted during placement using shortcuts. Refer to the Placement Shortcuts section to learn more about the shortcuts.
  • The current route length is displayed in the Net Length Gauge. Press the Shift+G shortcut to toggle the gauge on or off.

The current route length will be in accordance with the mode selected in the Target Length section of the Properties panel. Refer to the interactive length tuning page to learn more about controlling the target length, configuring the design rules and using the Net Length Gauge.

Attributes can be modified during placement by pressing the Tab key to access the Properties panel. Note also that interactively editing an accordion, such as dragging to change the amplitude, will also update the settings in the Properties panel. The current settings in the Properties panel become the default settings for further accordion placement.

Placement Shortcuts

The shortcuts available during length tuning include:

Shortcut Function
Spacebar Cycle through the three Styles of tuning pattern
, (comma) Decrease amplitude by the amount specified for the Amplitude Increment
. (full stop) Increase amplitude by the amount specified for the Amplitude Increment
3 Decrease space by the amount specified for the Gap Increment
4 Increase space by the amount specified for the Gap Increment
1 Decrease corner miter by the % specified for the Miter Increment
2 Increase corner miter by the % specified for the Miter Increment
Y Toggle starting direction
Tab Open the Properties panel in Accordion mode
Shift+G Toggle Length Tuning Gauge on/off

You only need to remember one shortcut, Shift+F1. This is the shortcut for shortcuts - use it during any Altium NEXUS interactive command to see a list of shortcuts for that command.

Graphical Editing

This method of editing allows you to select a placed Accordion object directly in the workspace and graphically change its size and shape.

When an Accordion object is selected, its polygonal outline is displayed as shown in the animation below. The outer shape of the polygonal outline is defined by a series of edges: where each edge is represented by an end vertex at each end, shown as a solid white square (A in the image below); and a center vertex in the middle, shown as a hollow white square (B in the image below). Each end vertex represents the location where two edges meet.

Click and drag on an edge or a vertex to reshape the accordion's polygonal outline, press Shift+Space to change the editing mode.

Standard polygonal shape editing techniques are available for editing the shape.

When editing a polygonal object, there are three editing modes available, Slide/Miter, Incurvate (arc) and Move. The current mode can be changed while dragging a vertex or an edge by pressing Shift+Spacebar to cycle through the three modes.

  • Slide/Miter - click and hold on an edge or a center vertex to slide that edge; click and hold on an end vertex to miter the corner.
  • Incurvate - click and hold on an edge or a center vertex to incurvate that edge; click and hold on an end vertex to incurvate (arc miter) the corner.
  • Move - click and hold on an edge or a center vertex to break that edge into two edges; click and hold on an end vertex to freely move that corner.

Feedback about where the cursor is on the board and which editing mode is currently active can be viewed on the Status bar and in the Heads-Up display.

Non-Graphical Editing

The following methods of non-graphical editing are available:

Editing via the Properties Panel

Properties page: Accordion Properties

The properties of an Accordion can be edited in the PCB editor's Properties panel, which allows editing of all item(s) currently selected in the workspace.

The Accordion mode of the Properties panel.

During interactive length tuning, the panel can be accessed by pressing the Tab key.

To access the properties of a placed Accordion:

  • Double-click anywhere on the Accordion object.
  • Right-click on the Accordion perimeter then select Properties from the context menu.
  • If the Properties panel is already active, click anywhere on the Accordion object to select it.

The properties displayed in the panel reflect the settings that were used to create the selected accordion.

The following properties of the selected accordion can be changed via the panel:

  • Source - change the source to Manual then manually edit the Target Length to change the accordion length. If the length value is increased the accordion length will increase, but only as is permitted by the current selection outline. Because the Target Length is the overall route length, the accordion will disappear when the Target Length is set to be equal to or less than the original route length.
  • Style - the style of the selected accordion can be switched between the three available styles. The Gap and Miter values can also be interactively edited.

Editing Multiple objects

The Properties panel supports editing multiple objects, 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.

Editing via the List Panel

Panel page: PCB List

The 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 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 – allowing you to target and edit multiple design objects with greater accuracy and efficiency.

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