ap0128 managing design variation with variants

Managing Design Variation with Variants

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Product requirements may warrant the need to produce a variety of similar Printed Circuit Boards that all differ slightly from an underlying base design. For example, standard and deluxe versions of a commercial electronic product may differ in the functionality they offer, with the standard version incorporating a subset of the components used in the deluxe version.

Introduction

At the design level, one or more assembly variations of a board design can be defined using the assembly variants feature. An assembly variant is an alternately assembled

‘version’ of the original board design. It may vary from the original with respect to:

• the number of original design components it contains

• the specific part type/value of those components (e.g. a discrete component with a different value, or a faster logic component of the same or different technology family)

• varied component-level parameters (e.g. tolerance or voltage-rating of a capacitor, Manufacturer’s Part Number, etc).

The true power of the assembly variants feature is that variations of a design can be created without having to create and maintain explicit PCB design projects for each variant. You are simply controlling the population of components on the base board – fabrication of the PCB remains the same irrespective of whether the original (full design) or a variant of it is being manufactured. The variation, in physical terms, comes into play during the board assembly phase – whether a component is fitted or not and whether the default component from the base design is used or whether an alternate part is specified.

When generating manufacturing output, the base design is always used to generate fabrication-related documents (e.g. Gerber, ODB++, NC Drill, etc), but when generating assembly-related documentation (e.g. Bill of Materials, Pick and Place, Assembly Drawings, etc), the source from which the output is generated will depend on the assembly variant you wish to manufacture.

Defining assembly variants

The controls for adding, defining and removing assembly variants for a design can be found in the Assembly Variant Management dialog (Figure 1), accessed by choosing Assembly Variants from the main Project menu.

Initially, a design will not have any assembly variants defined and the dialog will list all components used on the original, fully populated board design. Sub-columns provide the following information for each component:

Figure 1. Command Central – the Assembly Variant Management dialog.

Summary This application note provides detailed information with respect to assembly variants, including their definition and generation of relevant output.

AP0128 Managing Design Variation with Variants

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Any number of assembly variants may be added and defined for a design. Variant information is stored in the project file.

• Logical – this is the component’s logical designator, as assigned to the component on the associated source schematic sheet

• Comment – this is the type of component (logic chip, connector, etc) or its value (e.g. resistance, capacitance, etc) and is taken from the value entered in the component’s Comment property field

• Designator – this is the component’s physical designator, as assigned to the component once placed in the PCB design

• Document – this is the source schematic document within the design project upon which the component may be found.

Note: In multi-channel designs, the logical designators for the replicated channel components may be the same on the schematic side, but each component will have a unique physical designator when placed on the PCB side. This will be reflected in the Assembly Variant Management dialog (Figure 2).

The lower region of the Assembly Variant Management dialog – also referred to as the Parameter Variations region – is used for specifying changes to the parameters of components that are to be fitted on an assembly variant. The region reflects the parameters (and their values) associated with the currently selected component in the region above. The component’s Comment property is also included, which can be used to specify an alternate part/value for the component on the variant board. Initially, with no assembly variants defined, only the original parameter values for the components in the base design will be displayed (Figure 3).

Adding a new assembly variant

A new assembly variant can be added either by clicking on the Add Variant button or by choosing the command of the same name from the dialog’s right-click menu. The Variant of [ProjectName] dialog will appear. Use the dialog’s Name field to give the assembly variant a meaningful name, as illustrated by example in Figure 4. A meaningful name can not only aid in distinguishing between multiple defined variants, but also can provide some indication as to the purpose of that variant. Click on the Parameters button to access the Variant Parameters dialog, from where you can define and manage any parameters for the variant (e.g. Revision, Approved By, Intended Use, etc). These can be used for your own internal documentation purposes. They are not used by any other part of the variant system and cannot be included as part of variant-specific output, such as printouts.

Figure 5. Define variant parameters as required.

Figure 3. Multi-channel components can have the same logical designator but unique physical designators.

Figure 2. Parameters for a component in the original (base) design.

Figure 4. Naming the new design variant.


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Selection of a variant is achieved by selecting a cell in one of the columns associated with that variant – in either the upper or lower regions of the dialog – and is verified by the column background color changing to dark grey.

With the name and any parameters defined as required, click OK in the Variant of [ProjectName] dialog – the new variant will appear in the Assembly Variant Management dialog (Figure 6).

Editing an assembly variant

A selected assembly variant can be edited either by clicking on the Edit Variant button or by choosing the command of the same name from the right-click menu for the dialog. The Variant of [ProjectName] dialog will appear, from where you can make changes to either the name for the variant or its associated parameters as required.

Duplicating an assembly variant You may have defined an assembly variant which includes many changes in relation to the base design. A subsequent assembly variant may be required, which is similar to this existing variant. Rather than adding a new variant and having to 'redo' most of the changes again, it would be faster and more efficient to simply duplicate the existing variant and make modifications to it. This functionality is provided through use of the Copy Variant and Paste Variant commands from the right-click menu. Simply ensure that the required variant is selected before launching the copy command. If you have multiple variants selected, the variant whose column contains the focused cell will be the one used in the copy.

Figure 7. Select the required variant and use the Copy Variant command.

Figure 6. Viewing the newly-added assembly variant.


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Once copied, use the paste command to insert the variant into the Assembly Variant Management dialog. The Variant of [ProjectName] dialog will appear with a default name for the new variant, in the format CopiedVariantName_1. Change the name as required, as well as making any changes to associated parameters for the variant.

Figure 8. Paste the copied variant back into the management dialog, renaming as required.

The pasted variant is an identical copy of the original, including any component fitting and component parameter variations.

Changing variant order You can change the order in which the variants are displayed in the Assembly Variant Management dialog. Simply click on the header for a variant, in the upper region of the dialog, and drag it horizontally to the required position. A valid position is indicated by the appearance of two green positional arrows (Figure 9).

Figure 9. Changing the order of defined assembly variants.

Removing an assembly variant

To remove a selected assembly variant, simply click on the Remove Variant button or choose the command of the same name from the right-click menu for the dialog. A dialog will appear prompting for confirmation to proceed with the deletion.


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The variant fitting information is linked to the schematic component using a Unique ID. This ensures that the information is preserved when performing a reannotation.

Specifying components for an assembly variant

Whether adding a new assembly variant or editing an existing one, the job becomes one of definition – which of the original design components to include on the variant and any changes to those components as appropriate to the purpose of the variant.

The entry for a variant in the upper region of the Assembly Variant Management dialog consists of two sub-columns – containing a check box and a textual display, respectively, for each component in the active project. The check box is used to specify whether a component from the base design is included on the variant (checked) or not (unchecked). Simply click on a checkbox to toggle its state. As you do so, the textual display will change between Fitted and Not Fitted.

Figure 10. Specifying component inclusion for an assembly variant.

By default, all components will be initially fitted for a newly-added assembly variant. This allows you to just concentrate on the components you wish to exclude or change.

Part of a design may cater for extended or advanced functionality and the particular assembly variant you are defining may need to exclude this functionality. In such a case, the checkbox associated with each component that is not to be fitted on the variant board should be unchecked (Not Fitted). The example image in Figure 11 shows an assembly variant based on a multi-channel mixer design. The standard (original) design has eight input channels. The defined variant has only four input channels. Therefore the components associated with input channels 5-8 are specified to not be fitted for this assembly variant.

Figure 11. Excluding components from an assembly variant.


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If you make any changes in the Assembly Variant Management dialog and then click Cancel, a dialog will appear asking for confirmation to discard all changes made. Click Yes to discard all changes made since the dialog has been open, or No to carry on editing.

The checkbox for each variant parameter is simply used to enable editing of that parameter's value. Put another way, it reflects whether the parameter is varied (checked) or not varied (unchecked).

Varying components for an assembly variant In some cases, the components used in an assembly variant may need to be changed in some way. For example, product requirements might dictate that logic functionality should be faster in an enhanced-speed version of a product. Base logic components may therefore need to be swapped for higher speed varieties. In a similar vein, the values of discrete components may need to be revised in order for the assembly variant to achieve specific operating constraints. In such cases, you not only need to specify that the component is fitted, but also specify an alternate part (or value) to be used. This is achieved using the lower region of the Assembly Variant Management dialog. The part type/value for a selected component in the upper region of the dialog is specified using the Comment parameter entry in the lower region. This value is taken from the component’s Comment property field. The original value for the base design is shown, along with the value currently specified for each defined assembly variant. By default, the initial value for a component’s Comment in an assembly variant will be the same as that in the base design (Figure 12).

To specify the use of an alternate part in an assembly variant, enable the checkbox associated with the Comment entry for that variant and type the new value directly. Figure 13 illustrates an example of specifying alternate parts to be used for low and high speed variations of a standard design.

Figure 13. Specifying alternate parts to be used in defined assembly variants.

Varying additional component parameters For a selected component in the upper region of the Assembly Variant Management dialog, the Parameter Variations region will also list all currently defined parameters for that component, as listed in the Parameters region of the associated Component Properties dialog.

In the same way that the Comment entry is used to specify an alternate part/value for a component in an assembly variant, use these additional parameter entries to change additional information with respect to components used in the assembly variants. For example, you could change the power rating or tolerance of a resistor, or change the part number and manufacturer-related information.

Batch update of parameters from a library component Varying a component and/or its additional parameters for an assembly variant is not always an easy task. The change could be trivial, requiring a different value for a capacitor and no other changes. It could also be near impossible – having to remember a 16-digit manufacturer's part number for example. To facilitate quick and efficient variation of components for assembly variants, the Assembly Variant Management dialog provides the ability to update the parameter fields based on a chosen component in a library.

To illustrate the use of this feature, consider the circuit fragment and variant set-up of Figure 15. The eight LED components in the base design are red in color. The defined assembly variant (Green LED Version) requires that these LEDs be green in color. At this stage, the parameter information for the variant has not been varied. As you can see, there are quite a few parameters that may require changing in addition to the Comment parameter – which will be used to specify the required component variation – and, rather than resorting to typing in the values manually, extracting those values for the required component straight from a library would be most beneficial.

Figure 12. The initial part type/value for a variant will be that of the base design.

Figure 14. Changing component parameter values for defined variants.


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Figure 15. Parameters for a defined assembly variant prior to being varied.

The varied component that you wish to use for the assembly variant is located using the standard Browse Libraries dialog. Access this dialog from the right-click menu by choosing Update Values From Library.

Use the Browse Libraries dialog to browse through the currently available libraries for the parent project. The available libraries consist of project libraries, installed libraries and libraries found along search paths defined in the Search Paths tab of the Options for Project dialog (Project » Project Options).

Clicking the ... button in the dialog will give access to the Available Libraries dialog, from where you can add/remove libraries to/from the overall list of those available to the project. The dialog also provides a search facility – accessed by clicking the Find button – allowing you to search for a specific component across the Available Libraries or in any library along an external search path. Once you have chosen the required component, click OK to access the Update Project Variants From Library dialog (Figure 16).


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Use of this feature in no way physically changes the base component on the schematic sheet. Parameters are neither created nor removed by this process.

Figure 16. Specifying parameter information to be used in the update.

The left-hand region of this dialog lists all parameters currently defined for the library component, as well as its Comment and Description fields. The right-hand region lists all assembly variants currently defined for the parent design project.

If a parameter exists for the library component but not for the original component in the base design, it will be unavailable for selection (grayed-out), leaving only those parameters that do match.

Simply enable the parameters whose values you wish to vary – by default all matching parameters will be enabled – and also the assembly variants to which the variation is to apply. Commands are available on the right-click menu to quickly enable or disable all entries in both regions. Upon clicking OK, the parameter value(s) from the library component will be used as the new parameter variation value(s) for the selected assembly variant(s).

Figure 17 illustrates the resulting parameter variations for our Green LED variant example.


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Figure 17. Parameter variation values extracted from library component and added to the target variant definition.

Editing techniques Various features are provided in the Assembly Variant Management dialog to enable quick and efficient definition of assembly variants for a design. The following sections take a closer look at these features.

Selection Unless you are editing on a single cell basis, the fastest way to make changes is always to define a selection of items and push a change to all items in that selection simultaneously. Standard multi-select features are supported in both regions of the dialog – Ctrl+click, Shift+click and click & drag. In addition, commands are available from the right-click menu for a region, allowing you to: • Select Column – all cells in the column containing the focused cell will become selected.

• Select All – all cells in all columns in the region will become selected.

• Invert Selection – all cells currently not included in a selection within the column(s) involved in that selection will become selected. The cells in the original selection will be deselected.

Select Column and Select All are particularly useful when copying information for manipulation in an external spreadsheet – see External copy & paste.

As well as being able to select and edit all components in the Assembly Variant Management dialog, you can also open the dialog directly from the schematic, with just the selected component(s) displayed ready for editing. For more information, see the section Accessing variant information from the schematic.

Filtering by variation Some designs may contain a large number of components. To allow you to concentrate only on components that vary between the base design and defined assembly variants – in effect hiding the clutter of non-varied components – use the Only Show Varied Components option, available from the right-click menu for the upper region of the Assembly Variant Management dialog.

A varied component is deemed to be one whose: • Inclusion state differs in one or more variants from that of the base design (i.e. has been set to Not Fitted) and/or

• has one or more parameters that differ in value – across one or more variants – to those of the base design.


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Figure 18 shows an example of the use of this filtering, where the majority of base design components are hidden, leaving only four components that have been changed for a defined assembly variant. Two have been specified as not to be fitted on the variant board, while the other two have had some underlying parameters changed.

Figure 18. Upper-region filtering – displaying varied components only.

You can also apply similar filtering to the lower region of the dialog, using the Only Show Varied Values option from the region's right-click menu. For the component(s) currently selected in the upper region of the dialog, only those associated parameters whose values differ – across one or more defined variants – from those of the base design, will be displayed.

This lower-region filtering is powerful when used in conjunction with upper-region filtering. In the example of Figure 19, two variants of a base design have been defined. Filtering has been applied to the upper region of the Assembly Variant Management dialog (Only Show Varied Components option enabled), resulting in only two varied components being displayed. The full parameter listing for these components – selected simultaneously – shows that the components differ in some way parametrically between variant and base designs. As you can see, many of the parameters remain unchanged between base and variants.

Figure 19. Lower-region unfiltered – displaying all parameters for selected components.

Figure 20 shows the resulting lower region of the dialog after filtering is applied (Only Show Varied Values option enabled). With the 'noise' of the unchanged parameters removed from display, you are free to concentrate only on those parameters that do change between board variations.


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Figure 20. Lower-region filtered – displaying parameters for selected components with varied values only.

Type-ahead data filtering This feature is particularly useful when the upper and/or lower regions of the Assembly Variant Management dialog contain a great many entries and allows you to quickly jump to an entry by directly typing within a data column.

To use the feature for quickly finding a component in the base design, based on its logical designator for example, simply click on a field inside the Logical column and type the first letter of the item you wish to jump to. For example, consider a list of project components appearing in the Assembly Variant Management dialog as shown in Figure 21.

If you wanted to quickly jump to component entries starting with the letter L, you would press that letter on the keyboard. The first designator in the list starting with L would be made active and the letter L would be highlighted to show that filtering of the list is based upon it, as illustrated in Figure 22.

Figure 21. Unfiltered data in the upper region of the Assembly Variant Management dialog.


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When editing multiple parameter values, type the value and press Enter to keep the cells selected after editing.

If there are multiple components whose designators start with the same letter and especially if the list of components is particularly long, simply type further letters to target the specific entry you require. To clear the current filtering, allowing you to enter a different starting letter, press Esc. Use the Backspace key to clear the previously entered filter characters, in sequence. You can use this feature to filter based on any column within the dialog. Use the Right Arrow and Left Arrow keys to switch between columns, or click directly on a field within a column. As you switch, the current filter for the column you are leaving is cleared.

Single variant editing To toggle the state of a checkbox for a single component or single parameter entry thereof, simply click directly on the corresponding cell. Similarly, to edit a value entry for a single component parameter, simply click directly on the corresponding cell and enter the value.

If you wish to set the same checkbox state for multiple components simultaneously, or the same value for multiple parameters of a component, you must first select the corresponding checkbox cells for those components, or value cells for those parameters. When all cells have been selected, right-click and choose the Edit Selected command from the pop-up menu that appears.

The focused cell – distinguished by a dotted outline – will become available for editing. Simply click on the cell’s checkbox or enter the parameter value and click away from the cell. The checkbox state/parameter value will be copied to each cell in the selection.

When defining whether a component is to be fitted on a variant or not, commands are available from the right-click menu that enable you to quickly set all selected components to either Fitted or Not Fitted (Figure 24).

Similarly, when enabling parameters to be varied for a fitted component, commands are available (Figure 25) to quickly set all selected parameters to Varied (checkbox checked) or Not Varied (checkbox unchecked).

Figure 25. Setting the inclusion state of multiple components simultaneously

Figure 22. Type-ahead filtering of the Logical data column by the letter L.

Figure 23. Editing multiple cells.

Figure 24. Setting the parameter variation state of multiple parameters simultaneously


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Whether defining component inclusion for a variant, or enabling a parameter value to be varied, it is the corresponding checkbox field that must be edited. To change the status of multiple components to Not Fitted for example, you must ensure that the checkbox field for each component is selected – and not the field containing the text entry – otherwise the Edit Selected and Set Selected As commands will not function.

Multi-variant editing Component inclusion and parameter variation states can be edited across assembly variants. Simply ensure all checkbox fields for the required components or component parameters are selected and then edit the state using one of the Set Selected As commands available from the right-click menu.

Cross-variant editing of parameter values is not supported.

Parametric editing of multiple components When editing the definition of a particular assembly variant, you may often need to edit the same parameter values for multiple, similar components. For example, you may need to change the Value, Supplier and Supplier Code for several capacitors in a design. Rather than having to modify the parameters on an individual component basis, the Assembly Variant Management dialog allows you to edit the parameters of multiple selected components simultaneously.

As you select components to edit in the upper region of the dialog, the parameters of those components will be listed in the lower region. The designators of the components selected for editing are listed as part of the Parameter Variations header – enabling you to instantly check which components you are editing (Figure 27).

Figure 27. Editing the parameters of multiple similar components (eight 0.1uF capacitors).

For a mutual parameter where the value of that parameter is the same between components, a single entry for that parameter will appear in the list, as shown in Figure 27. For a mutual parameter where the value of that parameter is different between components, separate entries for that parameter will appear in the list, with component designator(s) displayed to indicate which component a particular entry is associated to. Figure 28 illustrates this for two capacitors – one with value 0.1uF and one with value 10uF.

Figure 26. Editing component inclusion state for two variants simultaneously.


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Figure 28. Identifying parent components for mutual parameters possessing different values.

There may be times where you edit components that possess dissimilar parameters – one component may contain one or more parameters that the other(s) do not. Such a parameter will present as a single entity in the lower region of the dialog, giving the impression that it is shared by all selected components. When the variant information is saved, any modified value for the parameter will only be saved with respect to a component that truly possesses it. Put another way, if a component doesn't have that parameter, no value will be saved for it (and the parameter will not be created).

Internal copy & paste Checkbox states or component parameter values can be edited using the copy and paste features available within the dialog: • To copy a single entry, either right-click on the source cell and choose the Copy command from the pop-up menu that

appears, or click and hold on the source cell and use the Ctrl+C keyboard shortcut

• To copy multiple contiguous entries, select all required cells and either choose the Copy command from the right-click menu or use the Ctrl+C shortcut.

• To paste a single copied entry to a single destination cell, right-click on the destination cell and choose Paste from the pop-up menu, or click and hold on the destination cell and use the Ctrl+V keyboard shortcut.

• To paste a single copied entry to multiple contiguous destination cells, select all required destination cells and either choose the Paste command from the right-click menu or use the Ctrl+V shortcut.

• To paste multiple contiguous copied entries to destination cells, right-click on the destination cell and choose Paste from the

pop-up menu, or click and hold on the destination cell and use the Ctrl+V keyboard shortcut. The number of destination cells involved will be equal to the number of original copied entries (e.g. if you copy 2 contiguous checkbox state entries, 2 contiguous destination cells will be used to take the pasted information). Should you wish to copy the information into multiple destination cells, ensure that the number of destination cells selected is a multiple of the number of entries originally copied (e.g. if you copied 2 contiguous checkbox state cells, you can copy the information into 2, 4, 6 etc, selected destination cells – effectively making 1, 2, 3 etc pastes of the original copied information).


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External copy & paste Should you wish, you can copy the information presented in a region of the Assembly Variant Management dialog and paste it into an external spreadsheet, such as Excel. Commands on the dialog’s right-click menu allow you to quickly select the entire region content or a particular column. Alternatively, select part of a column to work on as required, using the standard multi-selection features (see Selection).

Figure 29 illustrates an example of information copied from the upper region of the dialog (component inclusion on defined assembly variants):

Figure 29. Copying component inclusion information to an external spreadsheet.

Figure 30 shows an example of variant parameter information copied from the lower region of the dialog:

Figure 30. Copying parameter variation information to an external spreadsheet.

Whereas the entire table contents may prove useful when editing variant information in an external spreadsheet, bear in mind that it is only the variant definitions that should be pasted back into the Assembly Variant Management dialog. Therefore select only the editable variant information, or part thereof, to copy back into the dialog.

When the information is pasted into the external spreadsheet application, all header information is stripped. Also, checkbox status will be represented as follows: • TRUE = checked

• FALSE = unchecked

These values will be translated back into the relevant checkbox entries upon pasting back into the Assembly Variant Management dialog.


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Variant definition information is available only from the Assembly Variant Management dialog. This information can be exported to file or printed as a report, but such information is not added at the schematic or PCB document level.

Saving variant definition information

For both regions of the Assembly Variant Management dialog you can save the entire grid contents, or specifically selected data, into an ASCII text file (tab-delimited). Use the Save All or Save Selected commands respectively, available from the dialog’s right-click menu in the corresponding region.

The Save Grid Contents To File dialog will appear, from where you can determine where, and under what name, the file is to be saved.

By default, the file will be saved using the name GridContents.txt.

For the grid contents saved from either region, the check box entry will either appear as True (checked) or False (unchecked).

Generating a variant report

You can generate variant reports directly from the Assembly Variant Management dialog. Two 'levels' of report can be generated – basic or detailed.

Basic report A basic-level report can be generated for either the upper or lower regions of the dialog. The report for the top region allows you to quickly assess which project components are fitted or not for a defined assembly variant. The report for the lower region provides the parameter variation information with respect to the currently selected component(s) in the upper region.

Simply right-click within a region and use the Report command from the menu that appears. The Report Preview dialog will open, with the generated report loaded ready. Use the Report Preview dialog to peruse, print and export the report in various formats.

Only information that is currently displayed in the corresponding region of the dialog will be presented in the report.

Figure 31. Saving data from the Assembly Variant Management dialog.

Figure 32. Basic-level report generated from the lower region of the Assembly Variant Management dialog.


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Detailed report A detailed report is a HTML-formatted document that incorporates information from both regions of the Assembly Variant Management dialog. Generate a report of this type using the Detailed Report command, available from the menu associated to the dialog's Menu button.

The Variant Report dialog will appear (Figure 34). The original base design and all defined assembly variants will be listed in this dialog, allowing you to configure exactly what you want reported.

The generated report could:

• Compare one specific assembly variant against the base design

• Compare one assembly variant against another

• Compare all assembly variants against the base design.

By default, all defined assembly variants, as well as the original base design, will be enabled for inclusion into the report. The exact information featured in the report will depend on the state of the Report Only Varied Components option:

• Full Non-Varied Information (option disabled) – all components are listed, showing their inclusion state in each enabled variant. For each component, all parameters and their values are listed.

• Full Varied Information (option enabled) - only those components that vary in some way between enabled variants are listed, showing their inclusion state in each variant. For each component, only those parameters that vary in some way between variants are listed, along with their values.

The report will be created and opened as the active document within the main design window. Figure 35 shows an example of a detailed report containing only information for components and parameters that vary somehow between the variants and the original base design (i.e. Report Only Varied Components option has been enabled).

Figure 33. Accessing the command to generate a detailed report.

Figure 34. Accessing the command to generate a detailed report.


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Figure 35. Generated detailed report showing only variations between defined variants and the base design.


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If you wish to access variant information for a single component, it is not necessary to select that component prior to launching the command.

Accessing variant information from the schematic

You may wish to access the variant-related information for components directly from the schematic. This can be achieved by selecting the components required, right-clicking over one of the components in that selection, and choosing the Part Actions » Assembly Variants command from the menu that appears. The Assembly Variant Management dialog will open with only those components in the selection displayed for editing.

Figure 36. Displaying components in context with the selection made on the schematic sheet(s).

Cross probing

You can quickly assess where in the base design a particular component resides, using the cross probe feature. Simply select a component entry in the Assembly Variant Management dialog, then right-click and choose the Cross Probe command from the menu that appears. Alternatively, double-click directly on a component entry.

The relevant source document will be made active and the component will appear highlighted, in accordance with the highlighting methods defined on the System – Navigation page of the Preferences dialog.


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Figure 37. Cross probing to a component on the source schematic document.

When accessing the Assembly Variant Management dialog for a project for the first time, the project will automatically be compiled. The cross probing feature is only available when the source schematic document for the target component is open (or open and hidden) and the project has been compiled. If the source schematic is currently closed or has been closed and reopened, a dialog will appear upon trying to cross probe alerting you to this fact and advising you to recompile the project before proceeding.


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Generating output for an assembly variant

Assembly and/or report-based output for a variant is, for the most part, generated using an Output Job Configuration file (*.OutJob). Such output includes schematic prints, assembly drawings and a Bill of Materials. In addition, variant information can be included as part of documentation generated using Altium Designer's Smart PDF feature.

The following sections take a look at the support available for documenting assembly variants.

Using an Output Job file

Output Job Configuration files are defined and managed within the OutputJob Editor. An Output Job file enables you to define design output configurations – assembly, reports, etc – exactly as required, all in the one convenient and portable document. The majority of documentation that can be generated for an assembly variant will be configured and output from an Output Job file.

A new Output Job Configuration file can be created for the active project by: • using the File » New » Output Job File

command

• right-clicking on the project’s entry in the Projects panel and choosing Add New to Project » Output Job File from the pop-up menu that appears.

The new file will be opened as the active document in the OutputJob Editor (Figure 38).

Initially, all of the predefined output generators - responsible for generating actual output of the associated type - are added to the file and configured using default setups. To quickly clear all of these default output generators and start with a 'blank canvas', simply press Ctrl+A, followed by the Delete key.

If a particular documentation type can be generated for assembly variants, the associated Variant field will become available. For Schematic Prints, the Data Source field must be set to [Project Physical Documents] in order to access the Variant field. (See the next section for further information). Use the Variant field to determine whether a particular variant of the design is used as the source when generating the output, or whether the full, base design is used. In the latter case, the entry should be set to the default [No Variations].

Figure 39. Specifying an assembly variant as the source for document generation.

Assembly variants can be used as the source when generating the following documentation types:

• Assembly Drawings • Pick and Place Files • Bill of Materials • Component Cross Reference Report

• Schematic Prints • Report Project Hierarchy • Report Single Pin Nets • Simple BOM.

Figure 38. The OutputJob Editor.


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It is important to remember that although such documentation types can be generated directly - using commands accessible from within the respective document editor (from the File and Reports menus) - these commands relate to the full base design and not to any variant of that design. The exception to this is documentation generated involving the Report Manager dialog (Bill of Materials, Component Cross Reference, etc), whereby you can select which variant to use directly within the dialog (see Direct report generation).

For further information on Output Job Configuration files, including output definitions and generation, refer to the OutputJob Editor Reference.

Schematic prints As mentioned in the previous section, an Output Job file can be used to generate schematic prints, the source of which can be an assembly variant. In reality, what this means is that the full design appearing on the source schematic document(s) is printed, with the ability to determine how components that are not fitted for that variant are drawn. In order to access and nominate a source assembly variant for use in generating the prints, you must set the Data Source field for the corresponding Schematic Prints output generator to [Project Physical Documents]. Use of the project's physical structure means that schematics will be expanded from logical sheets to physical sheets – obtaining separate prints for each channel in a multi-channel design.

Figure 40. Enabling use of variants by setting the data source to use the physical structure.

Once you have configured the output generator to use the required assembly variant as its source, you will need to specify how you want the non-fitted components handled 'graphically' on the printed sheets. Options for doing this are available in the Schematic Drawing Options region of the Variant Options dialog (Figure 41). Access to this dialog is made through the Assembly Variant Management dialog. Simply choose the Variant Drawing Style command from the menu associated to the dialog's Menu button.

Figure 41. Accessing variant drawing style options.


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The components that are not fitted for the source variant – as determined in the Assembly Variant Management dialog – are still drawn on the generated printouts, but drawn as though they were masked. The Variant Options dialog simply provides you with the ability to overlay more 'obvious' graphics or text so that you can better distinguish those components.

Figure 42 illustrates the appearance of four LED components that are not fitted for a particular assembly variant of a design. In this case, no additional overlay graphics or text have been used.

Use the available schematic drawing options in the dialog to define the required drawing overlay as required. The available options are:

• Graphics – a red cross or gray meshed box

• Text – the appearance of which can be changed.

You could also combine one of the graphic options with text.

As you make a choice, an example of the result will appear in the associated preview window.

Figure 43 illustrates different overlays used for the four LEDs of Figure 42.

Figure 43. Appearance of non-fitted components using various overlays.

Labeling the print with the variant name Schematic prints may be generated for a number of assembly variants, in addition to the base design itself. To identify which prints belong to which variant, a special string can be placed on the source schematic documents. Simply add the special string =VariantName to a schematic document. When the output is generated, the string will be interpreted, using the name of the variant currently assigned in the Variant field associated to the Schematic Prints output generator (in the OutputJob Editor).

Figure 42. Appearance of non-fitted components (without overlay).


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Figure 44. Using a special string to display variant naming on a printed schematic document.

PCB assembly drawings You can also control the way in which non-fitted components are handled graphically on generated PCB Assembly drawings. Options for doing this are available in the PCB Drawing Options region of the Variant Options dialog (Figure 45).

Figure 45. Specifying PCB drawing options in the Variant Options dialog.

By default, components that are not fitted for a particular assembly variant are simply not drawn on the printout. Figure 46 illustrates this for the four LED components shown previously on the schematic side in Figure 42.

To add these components onto the print – drawn in draft mode (Figure 47) – ensure that the Display Not Fitted Components in Draft Mode option is enabled.

Use the available PCB drawing options in the dialog to overlay more 'obvious' graphics or text so that you can better distinguish those components. The available options are:

• A strike-through designator

• Graphics - a cross or meshed box – the color of which can be changed

• Text – the appearance of which can be changed (Stroke or TrueType, Text Height, etc).

You could also combine one or more options.

As you make a choice, an example of the result will appear in the associated preview window.

Figure 48 illustrates different overlays used for the four LEDs of Figure 46.

Figure 46. Default appearance of non-fitted components.

Figure 47. Adding non-fitted components to prints – displayed in draft mode.


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Set the report to use the original base design by choosing [No Variation] from the menu.

Figure 48. Using a special string to display variant naming on a printed schematic document.

Direct report generation

Report-based documentation that is configured using Altium Designer's Report Manager – such as a Bill of Materials or a Component Cross Reference Report – is typically defined as part of the Output Job Configuration file. As with all assembly and report based documents, you can generate them directly from within the schematic and/or PCB Editor. Whereas the majority of documents generated in this way use the base design only, with these particular documents you can choose which assembly variant you want to base the report on. From within the respective Report Manager dialog, specify the variant to be used as the source from the Change Variant sub-menu. This menu can be accessed from the dialog's right-click menu, or by clicking on the Menu button.

Figure 49. Accessing the Change Variant sub-menu.

The dialog name will change to reflect the assembly variant chosen. The data in the main grid will be updated with: • Components defined as Not Fitted for the selected variant removed

• Parameter values updated with those from the source variant, where they vary from the base design.


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Figure 50. Resulting Bill of Materials based on a chosen assembly variant.

For more information on creating a Bill of Materials, refer to the Generating a Custom Bill of Materials tutorial.

Smart PDF support

Altium Designer's Smart PDF feature also supports generation of schematic and PCB documentation based on the use of an assembly variant as the source. Use the Structure Settings page of the Smart PDF Wizard (Figure 51) to nominate the assembly variant that you wish to use. Note that the option to choose a variant will only be available when the Use Physical Structure option is enabled.

Figure 51. Specifying use of an assembly variant as part of the Smart PDF setup options.

As with schematic prints and assembly drawings generated from an Output Job file, you have the ability to control the graphical representation of non-fitted components on the schematic and PCB prints within the generated PDF. For more information on the options available and where to define them, refer back to the sections on Schematic prints and PCB assembly drawings, respectively.


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Figure 52. Schematic sheet within a generated PDF with graphical overlay for non-fitted components.

Figure 53. PCB composite print within a generated PDF with graphical overlay for non-fitted components.

Likewise, the use of the =VariantName special string is also supported by the schematic prints in the generated PDF file. For more information, refer back to the section Labeling the print with the variant name.

For more information on generating documentation using the Smart PDF feature, refer to the document Smart PDF Generation.


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Impact of design updates on assembly variants

If the components in the base design are changed in any way – for example components are updated from a library or a linked external company database – the defined assembly variants themselves will not be modified. The affect of base design updates on assembly variants can be summarized as follows: • Component inclusion states will remain unchanged. A part defined as Not Fitted before an update will remain as Not

Fitted after an update.

• Component parameters that are defined to be Not Varied for an assembly variant will acquire any new value arising from the update. Put another way, if a parameter is not specifically varied in its value, an update of its value in the base design will flow through to the assembly variant as well.

• Component parameters that have been specifically varied for an assembly variant will remain untouched. The specified value for such a parameter before the update will remain at that value after the update.

For information on using database libraries, refer to the Using Components Directly from your Company Database application note.

For information on Altium Designer's various update tools, refer to the Keeping Components Up-To-Date application note.


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Revision History

Date Version No. Revision

21-Mar-2005 1.0 Initial Release

01-Jun-2005 1.1 Updated for Altium Designer SP4

20-Sep-2005 1.2 Lower image fixed on page 8 to correctly reflect status of cells copied to external spreadsheet.

16-Oct-2006 2.0 Updated for Altium Designer 6.6.

17-Mar-2008 2.1 Updated PageSize to A4.

29-Apr-2008 2.2 Minor formatting updates and a new copyright note.

19-May-2008 2.3 Formatting issues fixed.

16-Mar-2011 - Updated template.

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