• Skip to main content
  • Skip to search
  • Skip to footer
Cadence Home
  • This search text may be transcribed, used, stored, or accessed by our third-party service providers per our Cookie Policy and Privacy Policy.

  1. Community Forums
  2. Allegro X PCB Editor
  3. xnets

Stats

  • Replies 9
  • Subscribers 160
  • Views 20439
  • Members are here 0
More Content

xnets

PhilR787
PhilR787 over 5 years ago

When I import a netlist for OrCad, xnets are generated.  They show up in the constraint manager and I can't remove members or delete the xnets.

How do I prevent xnets from being generated in the 1st place.

Thx,

Phil

  • Sign in to reply
  • Cancel
  • steve
    steve over 5 years ago

    You can add a Comps level property (Edit - Object Properties then Comps in the Find pane) called NO_XNET_CONNECTION with a value of True which stops the xnet being created. This can also be added in the schematic.

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
  • avant
    avant over 5 years ago in reply to steve

    Steve, assuming no constraints in the schematic are to be transferred to the PCB,

    could checking the "ignore electrical constraints" box in the setup for exporting a netlist be an easy option?

    We setup constraints at the board level and if we don't check the box our board level constraints get hosed.

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
  • steve
    steve over 5 years ago in reply to avant

    So once you have invoked Constraint Manager at the front end (from Capture) the design get locked in a Constraint Flow and to avoid the issues you are seeing you MUST back annotate the board to the schematic which will transfer all the constraints from PCB to schematic. This does work very well.

    • Cancel
    • Vote Up +1 Vote Down
    • Sign in to reply
    • Cancel
  • PhilR787
    PhilR787 over 5 years ago in reply to steve

    Steve, you are correct.  I invoked the constraint manager in Capture (even tho I didn't use it) and then I started getting the xnets.  I add the property NO_XNET_CONNECTION and now the xnets are gone.  How did you find out about adding the property?  Sucks that Allegro forces me into a different flow without asking/warning that it's happening.

    Thanks for the help.

    Phil

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
  • steve
    steve over 5 years ago in reply to PhilR787

    The property has been around fo a long time but was to restrict xnets being created in the old flow if you use Signal Analysis. You are warned when you first invoke CM in Capture. The flow is really helpful if you want to set constraints, you just need to ensure you always back annotate once you start that flow. 17.4 is better with Design Sync

    • Cancel
    • Vote Up 0 Vote Down
    • Sign in to reply
    • Cancel
>
Cadence Guidelines

Community Guidelines

The Cadence Design Communities support Cadence users and technologists interacting to exchange ideas, news, technical information, and best practices to solve problems and get the most from Cadence technology. The community is open to everyone, and to provide the most value, we require participants to follow our Community Guidelines that facilitate a quality exchange of ideas and information. By accessing, contributing, using or downloading any materials from the site, you agree to be bound by the full Community Guidelines.

© 2025 Cadence Design Systems, Inc. All Rights Reserved.

  • Terms of Use
  • Privacy
  • Cookie Policy
  • US Trademarks
  • Do Not Sell or Share My Personal Information