Autolinking is a process of mapping files to the correct layers of the board. The import module is designed to support Gerber and Drill files from a wide variety of CAD systems; while each CAD system has its own approach to naming its output files. The autolink processor applies several different strategies for mapping filenames to board layers:
- Gerber Job file: If the product you are importing contains a Gerber job file (*.gbrjob) then file linking information will be extracted from the Gerber Job file.
- Gerber X2 File Function attributes: Each unmapped file is scanned, looking for a valid Gerber X2 .FileFunction attribute in the file header (or comments). If found, the attribute is used to link the file.
- Link filters: The link filter which best matches the files being imported (if any) is used to map all unmapped files whose filenames are specified in the filter.
- Filename analysis: Each remaining unmapped file has its filename is analyzed, looking for commonly used text substrings that indicate the layer to which the file should be linked.
After autolinking, the left pane of the status bar shows how many files were linked by each of these strategies.
Note: Once a file has been linked, then it will not be re-linked by a succeeding strategy.
The Gerber Job file and Gerber File Function attributes are the most reliable linking strategies. However, these are relatively new features in the Gerber Format, and are usually not available when older CAD systems are used.
Link filters and filename analysis are usually able to map most or all of the image files properly. But it might also make wrong assumptions. The user is strongly advised to review the file mappings carefully.
Note: For best results, Altium users should enable the Protel filter (in the Filter Manager) and disable all other filters (except Elprint, which can not be disabled).
If, during autolinking, two files appear to belong to the same layer, both files are displayed graphically and the user may choose which file to link to the layer. The other file will be left unlinked, and may be manually linked to its correct layer after autolinking has finished. This situation typically arises when there are several mechanical files and the autolinker is unable to determine which one contains the board contour.
When Autolinking is enabled, it is only automatically applied the first time files are added to a product. The autolink process may be repeated by right-clicking on the file list and choosing Re-link files.
If, for some reason, a file is improperly linked during autolinking, this may be corrected by relinking the file to the correct layer.
If, during autolinking, a file has been linked to the Board outline layer, then an attempt will be made to automatically define the outer and inner (if any) contour objects. This operation may be enabled or disabled by selecting the Configure|Automatic outline menu item to toggle the state.
Link filters
A link filter is a set of filename substrings, each mapped to its appropriate layer name. There are a handful of pre-defined link filters built into the import module. Additional filters may be defined:
- The Configure|Manage link filters menu command opens the Filter Manager
- The Configure|Create filter as mapped command creates a filter from the current file mappings
The Link filters strategy compares all image file names with all filename substrings in all enabled link filters. It then selects the “best” filter to use when autolinking. The “best” filter is the filter having the largest number of filename matches. However, more than half of the image files must match for a filter to be considered among the best.
