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When auto-connecting a trace from a via how do you stop the software from changing netnames when a shape is on that layer.

Lennie

I have a via with netname VBAT. I have a dynamic shape on the same layer.  When I route from the via and stop in the shape area and end the route the netname changes to the name of the shape.  How do I stop this from happening ? 

  • What net is assigned to the shape & is it the same as VBAT.

    I have never seen Allegro just changing a net name on the fly. This would go against every rule one would expect from a host cad system.

    Seems odd you are seeing this. If the net name for the shape was VBAT then one would expect a merge as the nets are the same. If not the dynamic shape should clear to make way for the VBAT route.

  • Net Name of Vias are normally inherited by a Pin or Shape and there is no guarantee it will remain connected to the expected net.  A good rule of thumb is to make sure the Via finds its way back to a Pin using a Cline connection to ensure that it maintains the Net with attaching the Via to a Static Shape a close second.

    Another option is to add the Property RETAIN_NET_ON_VIAS on the Net so its attached Vias don't easily jump to a different net.

    Hope this helps,
    Mike Catrambone

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