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Error When Editing Constaints in Allegro 17.4: CMAVP-2

ameehan2

My Allegro .brd was originally done in 17.2. We moved to 17.4, engineer made changes that somehow wrecked some trace width constraints. When I open CM and try to correct them, I get this message:

All I need to change is the 0.0820 to 0.0890 and I don't understand the message. Yes, I've tried the max width first, but still get the same message.

Any feedback would be greatly appreciated.

Thanks.

Alexis

  • excellon1

    Try run a database check on the design to see if anything shows up first. It looks to me like some corruption exists with the design.

    If you cant resolve this maybe go back to the prior design in 17.2 and do a DB Check there. Then open the design in 17.4.

  • ameehan2
    in reply to excellon1

    Thank you. The database check showed no errors, but I did notice that the physical Cset had changed with the new netin. The engineer claims that he changed nothing in the constraints, but this set still changed. Wondering why?

  • excellon1
    in reply to ameehan2

    What field changed in the PCS ?

    Netin is seeing something derived from the schematic. Perhaps something like a diff-pair or critical net got assigned a property in the schematic.

    Are you using capture or HDL as your front end ?

  • ameehan2
    in reply to excellon1

    Using Capture. The PCS changed to default for a group of nets. The engineer says he didn't change anything in properties, so it's odd. 

  • Wild
    in reply to ameehan2

    I have had the issues over the years when I output a netlist from Capture to Allegro my constraints would changing in Allegro.  The simple solution I found is to disable the ECS export during netlist.  Example attached.  However, I have found a belt and suspends approach: in Allegro, once I have all my constraints set the way I want them, I export the constraints to a dcf file in my Allegro directory.  So when I screw up, or a coworker who hates constraints deletes them, I can recover the constraints. Slight smile

    Hope this helps,

    Wild...

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