This can be accomplished by opening Constraint Manager and selecting File > Import > Worksheet File.
There are three different file types acceptable to import; Text (tab delimited), Formatted Text (Space delimited) and CSV (Comma delimited).
All three formats can be exported from an Excel spreadsheet.
An example of a tab delimited Excel output for importing into the Net > Routing > Total Etch Length constraint is:
Net:CLOCK TEST_CSET 20 55
For this example, the tab delimited fields consist of:
Col A Col B Col C Col D Col E Col F
Net:Netname Ref Cset Min value Max value
- If a field is blank, a column must still be present in the Excel spreadsheet as a placeholder.
- The design "board_name" must match the name of the .brd file
Hope this helps.