String

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Modified by Admin on Sep 13, 2017

Parent page: Objects

Placed String objects.

Summary

A string is a primitive design object. It places text on the selected layer in a variety of display styles and formats, including popular barcoding standards. As well as user-defined text, "special strings" can be used to place board or system information on the PCB.

Availability

Strings are available for placement in both PCB and PCB Library Editors:

PCB Editor

Choose Place » String [P, S] from the main menus.
Click the button on the Wiring toolbar.

PCB Library Editor

Choose Place » String [P, S] from the main menus.
Click the button on the PCB Lib Placement toolbar.
Right-click in the workspace and select Place » String from the context menu.

Placement

After launching the command, the cursor will change to a cross-hair and you will enter string placement mode. A string will appear "floating" on the cursor:

Position the cursor and click or press Enter to place a string.
Continue placing further strings, or right-click or press Esc to exit placement mode.

Additional actions that can be performed during placement are:

Press the Spacebar to rotate the string anti-clockwise or Shift+Spacebar for clockwise rotation. Rotation is in accordance with the value for the Rotation Step, defined on the PCB Editor – General page of the Preferences dialog.
Press the X or Y keys to mirror the string along the X-axis or Y-axis respectively.
Press the L key to flip the string to the other side of the board.
Press the + and - keys (on the numeric keypad) to cycle forward and backward through all visible layers in the design respectively – to change placement layer quickly.
Press the Tab key to access an associated properties dialog, from where properties for the string can be changed on-the-fly.

While attributes can be modified during placement (Tab to bring up associated properties dialog), bear in mind that these will become the default settings for further placement unless the Permanent option on the PCB – 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.

Non-Graphical Editing...

The following methods of non-graphical editing are available:

...via an Associated Properties Dialog

This method of editing uses the following dialog to modify the properties of a string object.

The String dialog.

The String dialog can be accessed prior to entering placement mode, from the PCB Editor – Defaults page of the Preferences dialog. This allows the default properties for the string object to be changed, which will be applied when placing subsequent strings.

During placement, the dialog can be accessed by pressing the Tab key.

After placement, the dialog can be accessed in one of the following ways:

Double-clicking on the placed string object.
Placing the cursor over the string object, right-clicking and choosing Properties from the context menu.
Selecting the Edit » Change command, then clicking once over the placed string object. This method allows consecutive editing for multiple objects.

Quickly change the units of measurement currently used in the dialog between metric (mm) and imperial (mil) using the Ctrl+Q shortcut. This affects the dialog only and does not change the actual measurement unit employed for the board, as determined by the Measurement Unit setting in the Board Options dialog (Design » Board Options).

...via an Inspector Panel

An Inspector panel enables the designer to interrogate and edit the properties of one or more design objects in the active document. Used in conjunction with appropriate filtering, the panel can be used to make changes to multiple objects of the same kind, from one convenient location.

...via a List Panel

A List panel allows the designer 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, it enables the display of just those objects falling under the scope of the active filter – allowing the designer to target and edit multiple design objects with greater accuracy and efficiency.

Graphical Editing

This method of editing allows you to select a placed string object directly in the workspace and change its location, rotation, orientation or, in the case of inverted strings, size.

When a non-inverted string object is selected, the following editing handle is available:

A selected String (non-inverted).

Click and drag B to rotate the string about point A.
Click anywhere on the string – away from any editing handles – and drag to reposition it. The string will be held by point A and can be rotated (Spacebar/Shift+Spacebar) or mirrored (X or Y keys to mirror along the X-axis or Y-axis respectively).

When an inverted string object with an editable bounding rectangle (inverted rectangle) is selected, the following editing handles are available:

A selected String (inverted, and using an inverted rectangle).

Click and drag B to rotate the string about point A.
Click and drag C to resize the rectangle in the vertical and horizontal directions simultaneously.
Click and drag D to resize the rectangle in the vertical and horizontal directions separately.
Click anywhere on the string – away from any editing handles – and drag to reposition it. The string will be held by point A and can be rotated (Spacebar/Shift+Spacebar) or mirrored (X or Y keys to mirror along the X-axis or Y-axis respectively).

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 PCB Editor – General 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. Double click on the locked object directly and disable the Locked property or disable the Protect Locked Objects option, to graphically edit the object.

Special Strings

While string objects can be used to place user-defined text on the current PCB layer, it's not just user-defined text that can be placed. To assist in producing documentation, the concept of "special strings" is used. These act as placeholders for design or system information that is to be displayed on the PCB at the time of output generation.

Default sets of predefined special strings are provided for use with new PCB documents. But the designer can also add their own custom special strings by defining additional parameters at the project-level (available for use across all schematic sheets and PCB documents in the project).

Placing a Special String

To use a special string on a PCB, simply place a string object and set its text to be one of the special string names.

On a PCB document, special strings are characterized by the prefix '.' (e.g. .Layer_Name, .Net_Count, etc). The list of available special strings – both predefined and custom – can be seen by clicking the drop-down arrow associated to the Text field, in the String dialog.

Accessing special strings for a placed string object.

Revealing Special Strings in the Workspace

The values of some special strings can only be viewed when the relevant output is generated. Most special strings can be viewed directly on-screen however, by enabling the Convert Special Strings option, on the View Options page of the View Configurations dialog (Design » Board Layers & Colors).

Enabling the Convert Special Strings option allows the data for certain special strings to be viewed in the workspace, prior to output generation.

PCB Predefined Special Strings

The following are the predefined, system-based special strings available for use on a PCB document:

.Application_BuildNumber – the version of the software that the PCB is currently loaded in. When generating Gerber output, this string will record the software build that the design was created on.
.Arc_Count – the number of arcs on the PCB.
.Comment – the comment string for a component (used in designing component footprints).
.Component_Count – the number of components on the PCB.
.ComputerName – the name of the computer on which the software is installed and running.
.Designator – the designator string for a component (used in designing component footprints).
.Fill_Count – the number of fills on the PCB.
.Hole_Count – the number of drill holes on the PCB.
.Layer_Name – the name of the layer the string is placed on.
.Legend – a symbol legend for mechanical drill plots. This string is only valid when placed on the Drill Drawing layer.
.Net_Count – the total number of different nets on the PCB.
.Net_Names_On_Layer – the names of all nets on the specific layer. This string is only valid when placed on an internal plane layer.
.Pad_Count – the number of pads on the PCB.
.Pattern – the names of the component footprints used on the PCB.
.Pcb_File_Name – the path and file name of the PCB document.
.Pcb_File_Name_No_Path – the file name of the PCB document.
.Plot_File_Name – for generated Gerber output, this string identifies the file name of the Gerber plot file. For printed output, it identifies the layer depicted within the output. For ODB++ output, it identifies the name of the parent folder in which the files are stored.
.Poly_Count – the number of polygons on the PCB (consisting of polygon pours, internal planes and split planes).
.Print_Date – the date of printing/plotting.
.Print_Scale – the printing/plot scale factor.
.Print_Time – the time of printing/plotting.
.Printout_Name – the name of the printout.
.SlotHole_Count – the number of slotted holes on the PCB.
.SquareHole_Count – the number of square holes on the PCB.
.String_Count – the number of strings on the PCB.
.Track_Count – the number of tracks on the PCB.
.VersionControl_RevNumber – the current revision number of the document. Version control must be used for this string to contain any information.
.Via_Count – the number of vias on the PCB.

Remember that the full list of special strings available in the String dialog will also include any derived from user-defined project-level parameters.

Fonts and Barcodes

The PCB Editor offers the ability to use Stroke-based or TrueType fonts for string objects. Choice of font is made from within the String dialog. In addition, support is available for presenting text strings in Barcode format. Barcodes are commonly used to tag and identify PCBs, streamlining inventory tracking for example, through use of automated scan-machines.

Stroke Fonts

Three Stroke-based fonts are available – Default, Sans Serif and Serif. The Default style is a simple vector font which supports pen plotting and vector photoplotting. The Sans Serif and Serif fonts are more complex and will slow down vector output generation, such as Gerber.

To use a Stroke-based font, simply enable the Stroke font option in the String dialog and choose a font type from the drop-down field in the Select Stroke Font region.

Resulting appearance of the various Stroke-based fonts, in order, in the workspace.

The Stroke-based fonts are built into the software and cannot be changed. All three fonts have the full IBM extended ASCII character set that supports English and other European languages.

TrueType Fonts

When using TrueType fonts, TrueType and OpenType (a superset of TrueType) fonts found in the \Windows\Fonts folder will be available for use. The feature also offers full Unicode support.

Note that only detected (and uniquely named) root fonts will be available for use. For example, Arial and Arial Black would be available but Arial Bold , Arial Bold Italic , would not.

To use a TrueType font, simply enable the TrueType font option in the String dialog and choose a font type from the drop-down field in the Select TrueType Font region. Use the Bold and/or Italic options to add emphasis to the text as required.

Resulting appearance of various example TrueType fonts in the workspace.

When using a TrueType font for a string object, additional options are available. Enable the Inverted option to display the text as inverted, with control over the size of the border around the text.

An example of inverted TrueType text.

The Use Inverted Rectangle option provides control over the bounding rectangle for the inverted text, including rectangle size, text justification within the rectangle, and an offset for the text in relation to the rectangle's edge.

The Use Inverted Rectangle option and its controls are only available when working with inverted text.

Fine-tune appearance of inverted text with control over the bounding rectangle.

As a value is entered into the Width and Height fields for the bounding rectangle, pop-up hint text will advise the minimum values that can be entered, based on the actual width and height of the text string itself.

Embedding TrueType Fonts

The PCB Editor – TrueType Fonts page of the Preferences dialog provides options for embedding TrueType fonts when saving a design, and for applying font substitution when loading a design. Embedding fonts is useful when text is required to be displayed in a font that may or may not be available on a target computer upon which the design is loaded. Font substitution enables specification of a TrueType font to be used as a replacement when loading a design where fonts have not been embedded and where fonts may not be available on the computer upon which the design is currently loaded.

TrueType font preferences.

Barcodes

Ability is provided to place barcode symbols directly onto a PCB on any layer, allowing barcodes to be easily imprinted on a PCB as part of the manufacturing process.

To use a Barcode font, simply enable the BarCode font option in the String dialog and define the display options as required in the Select BarCode Font region.

BarCode ISO Code 39 (US Dept of Defense standard) and Code 128 (global trade identification standard) are supported, and the actual text string that the barcode is derived from can also be displayed by enabling the Show Text option.

When showing text, choose a TrueType font to be used, and set the height for the text accordingly.

Example barcode with original (human-readable) text beneath.

Specify the height and width of the barcode using either a desired overall width or a minimum barcode element width to control sizing. Whichever method is used, be sure to use sizing that will render the barcode readable to the appropriate scanners!

By using a combination of barcode and inverted text strings, along with fills if necessary, a nice barcode area can be defined on a board, with more information textually than would otherwise be afforded by just the originating barcode text.

Example using inverted barcode and additional inverted text strings.

Notes

The .Designator and .Comment special strings are added to a component in a PCB library. Use these if you need to control the location of these attributes on a component. They can be placed on any layer. The standard designator and comment can be hidden if desired.