Altium NEXUS Documentation

Working with an Accordion Object on a PCB in Altium NEXUS

Created: September 7, 2019 | Updated: June 3, 2021
All Contents

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 or Accordion dialog.


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
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:

Via the Accordion Dialog or Properties Panel

Properties page: Accordion Properties

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

 The Accordion dialog on the left and the Accordion mode of the Properties panel on the right.

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

After placement, the Accordion dialog can be accessed by:

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

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

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

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

If the Double Click Runs Interactive Properties option is disabled (default) on the PCB Editor - General 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. 
Press Ctrl+Q to toggle the units of measurement currently used in the panel between metric (mm) and imperial (mil). This only affects the display of measurements in the panel; it does not change the measurement unit specified for the board, which is configured in the Units setting in the Properties panel when there are no objects selected in the editing workspace.

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.

Found an issue with this document? Highlight the area, then use Ctrl+Enter to report it.



We're sorry to hear the article wasn't helpful to you.
Could you take a moment to tell us why?
200 characters remaining
You are reporting an issue with the following selected text
and/or image within the active document: