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 Rats nest / uconnected pins on symbol update. 

Last post Fri, Nov 15 2013 6:40 AM by steve. 6 replies.
Started by cadSmith 14 Nov 2013 11:33 AM. Topic has 6 replies and 1747 views
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  • Thu, Nov 14 2013 11:33 AM

    • cadSmith
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    Rats nest / uconnected pins on symbol update. Reply

    Hello all,

    I'm working with allegro 16.6 and am exporting a an already routed PCB design as IDF to solidworks folks.

    It turns out one of the symbols in the pcb design was missing height information.  I opened the symbol in allegro and added the height info.

    Then I went into the pcb design place->update symbol and selected the proper symbol.  The symbol updates , I exported the IDF, and now the solidworks folks are happy.

    One problem however: the symbol's pins in allegro all have ratsnest on them now.  I can go and reroute the clines next to the pins and this seems to fix the issue, however, it would take a long time to do all of the pins and could potentially be error prone.

    I'd like to point out that before the symbol update there were no ratsnest / unconnected pins on in the design and specifically on this particular symbol.

    Is there anyway to connect the pins / fix the ratsnests?

     

    Thanks in advance. 

    • Post Points: 20
  • Thu, Nov 14 2013 11:52 AM

    • chads108
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    Re: Rats nest / uconnected pins on symbol update. Answer Reply

     It sounds like your footprint units are different than your board units which results in a rounding error.

    You can try running Tools => Derive Connectivity and select the top option, Convert Lines to Connect Lines.  I believe that should work for at least most of the connections.

    • Post Points: 20
  • Thu, Nov 14 2013 12:26 PM

    • cadSmith
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    Re: Rats nest / uconnected pins on symbol update. Reply
    It worked! Thank you kind sir! In general, is this common since footprints and track spacing on pcb isn't going to match up most of the time? Or am I thinking of this wrong? Thanks again!
    • Post Points: 20
  • Thu, Nov 14 2013 1:36 PM

    • chads108
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    Re: Rats nest / uconnected pins on symbol update. Reply

     I think as long as you stay in the same units, e.g. mils and mils, you are fine.  If you are doing mils and millimeters, then you can get rounding errors.  We do everything in millimeters using same decimal places and have never had a problem with symbol refresh.  I understand not all companies have that luxury though.

    • Post Points: 20
  • Thu, Nov 14 2013 2:16 PM

    • cadSmith
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    Re: Rats nest / uconnected pins on symbol update. Reply
    Thanks again! I think I will try and implement this. Could you speak a bit on why you chose mm over mils. I am not partial to either but would like to understand a bit more. I'm used to making footprints in either (which i'll now stick to one or the other). However, I usually think of spacing and trace width in mils. Since SI seems like nice standard it seems like an obvious choice. On the other hand, since I usually always do layout in mils my mind finds it a bit easier at this moment. Please share thoughts If possible. Thanks again for all the insight.
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  • Fri, Nov 15 2013 5:50 AM

    • chads108
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    Re: Rats nest / uconnected pins on symbol update. Reply
    It seems that more and more specs are being generated in MM, especailly with the global market, so I was finding myself converting from MM to mils more often than not.  I decided not to fight it anymore and starting building footprints in MM.  Also, quite a bit our fabrication gets done outside of the country as well, and since everybody else in the world uses MM, we just made the switch.  I admit, it is difficult at best to think in MM, especially for an old dog like me, but I'm getting there.  I even managed to get the mechanical guys to switch over to MM which makes everything go much smoother with everyone on the same page.
    • Post Points: 20
  • Fri, Nov 15 2013 6:40 AM

    • steve
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    Re: Rats nest / uconnected pins on symbol update. Reply

    I'm pretty sure that IPC uses MM as a default now so if you build your footprints to IPC 7351 then you should be using MM as the unit. This is also incorporated into the footpint name.

    • Post Points: 5
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Started by cadSmith at 14 Nov 2013 11:33 AM. Topic has 6 replies.