4 Replies Latest reply on Mar 4, 2010 5:17 AM by simpsond1

    DxD and PADS collaboration...




      Seems that when I carry a new netlist from DxD over to PADS Layout (PADS version 9.1) that I lose many of the settings that I have set up in PADS, i.e., diff pairs, trace widths, layer 'biasing', selected layers for routing, etc.


      I know that diff pairs can be 'paired up' in DxD (and I have begun doing that), but can all of these other PADS 'constraints' be saved in DxD (at least backannotated to DxD from PADS Layout)?


      How can I keep design parameters / constraints that I have setup inside PADS to retain their settings when bringing a revised DxD netlist over to PADS Layout?



        • 1. Re: DxD and PADS collaboration...

          To my knowledge, conditional rules are not supported in DxDesigner in the PADS flow.  I think this is the only limitation.  To stop design rules from passing, make sure the Design Rules box is turned off in the Forward Annoation GUI in the DxDesigner Link.



          • 2. Re: DxD and PADS collaboration...

            Thanks for the reply, Ted...


            That certainly fixed the problem and lets me keep a bit more more of my hair in the process.


            I just hope that the capability of PADS Layout backannotating of some of this information back to DxD comes into play at some point.


            Thanks again...

            • 3. Re: DxD and PADS collaboration...

              You should be able to back annotate as long as you don't have any conditional constraints set up in PADS --- AND --- you are not working in METRIC units.  What will happen is your CNS file will be updated with any CLASS rules you have set up in PADS.  It used to be (PRE 2007_3) that "net" contraints that were different than the "default" were recorded as attributes on the individual net in DxDesigner unless the net was assigned to a class.  These may now also be stored in the CNS file.


              Make sure you have a separate CNS file for each design you are going to pass constraints on.  Otherwise, the default CNS file will grow into a monster with all your different design values.  Just copy the PADS9.cns file from your WDIR into the project directory and set up its path in the <Setup><Settings> section of DxDesigner .  (assuming you are working in mils).


              One more thing,  when passing contraints always beckup your work before running a forward or backwards annotation.  Contraint passing is an easy way to mess things up if you are not very-very careful


              Good luck! 

              • 4. Re: DxD and PADS collaboration...



                Thanks again for the feedback. Also for the suggesion regarding the CNS file...


                I also use Allegro Editor and Allegro Design Entry (OrCAD Capture+). They also have similar constraint limitations when carrying constraint rules back and forth and can also bite you if you are not careful.


                I understand a bit more clearly now.