Beginning with the 16.6 Allegro PCB Editor, the environment variable UPDATE_ECSET_REFDES is now the default behavior.
Read on for more details …
Most Electrical Constraint Sets (ECSets) will map based on Reference Designator (RefDes) values. It is sometimes the only thing that is unique for pins in a topology:
In this picture, U21 and U44 have the same SI model and the same pin use. So the only way to differentiate them is by RefDes.
This topology may not map the same way if the design is re-sequenced (RefDes re-numbering). The RefDes renaming can be an automatic process for the whole design or done manually for one component.
In order to address this, the environment variable UPDATE_ECSET_REFDES is made the default behavior. It will change the RefDes in all ECSets based on updates in the design.
For example if U21 is renamed to A-1 in the .brd file, the same will happen to any instance of U21 in the ECSets contained in the .brd.
A new variable, NO_UPDATE_ECSET_REFDES, is added in the 16.6 release to disable the feature described above.
The variable NO_UPDATE_ECSET_REFDES can be added either at the Allegro command line or in your local env file.
Please share your usage of this capability.
Jerry “GenPart” Grzenia