Disappearing ratsnest

Occasionally, when moving a component, one or more of the ratsnests disappears. Why?


Can you post some screenshots of an example?

It’s possible that when you move a footprint onto an existing track or a zone, the pad is already connected. It’s also possible that the ratsnest line is drawn in some other location.

For example, with this schematic:


The ratsnest can for example be shown as:


And then, when R5 is moved a bit to the south some ratsnest lines move and are shown between R4 and R7.


The lines don’t vanish.

All the components are in parallel, thus the connection between R5 and R2 is now moved to R7 and R4.

As @pedro comments, the rartlines don’t vanish. The ratlines move to the two footprints (or the end of a track and a footprint or the ends of two tracks) that is the shortest distance on the net in question.
With Pauls’ example: The ratlines are between R2 & R5 because R5 is the closest to R1 - R4, but, when R5 is moved, R7 becomes the closest to R1 - R4, so the ratlines from R1 - R4 jump to R7.

Ratlines are lazy… they take the shortest route :slightly_smiling_face:

A better words for this is → It is suggesting to the designer the optimal path to route at that instance. :slightly_smiling_face:

I’ve been away for a few days. Not sure how to post screen shots, but it’s easy to describe. I have a transformer, a resistor, and a relay. Pin 1 of the transformer is connected to pin one of the resistor and pin 4 of the relay. Hover over the resistor and type M. If the resistor is closer to the transformer, the ratsnest to pin 4 of the relay goes away, leaving pin 4 unconnected. If you move the resistor closer to the relay, the line to pin 4 reappears but the one to the transformer disappears. Having the rat take the shortest path is normal behavior, but why does the other one disappear? Click on the resistor to place it and the other ratsnest reappears.

Even stranger, if you move either of the other 2 parts, all ratsnests remain connected and rubber band per normal operation.


OK, maybe I understand better now. You mean that while moving a footprint some pad may loose all ratsnest lines temporarily so that it seems to be totally unconnected to anything? And only while moving?

This is the normal behaviour.
The ratsnest lines tell you that at least one connection of the net remains unconnected.
The virtual connection does not disappear.
If there are several components belonging to the same net and all the ratsnets line would be shown, it should be an unreadable web.

Yes, but did you understand the problem correctly? I was trying to ask if it happens that some pad suddenly looses all ratsnest connections even when it should have one.

It’s normal behavior that the lines change places and the “web” of lines changes its shape, but if a pad is connected to other pads (in the schematic, so that it belongs to a net with some other pads), it should always have at least one line connected to it.

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.