Currently using Eagle ver 6.3, after almost 3 years.

The most pervasive difficulty (at basic level): a via is assigned to change layer during a rerouting; trying to delete it later is not allowed because Eagle considers it as part of the net (do it in the schematics, it says...!)

I recall deleting a via once after a sequence of wild attempts but could not repeat the series of events.

Could anyone help me on this? Gracias.

 

Have you tried to delete the wire in the schematic, and then re-wire it?

 

There are two ways to clear vias that you don't want. The safest way is to use rip-up and destroy routing containing the via and the via disappears. While that is the safest way, it can lead to a lot of redundant work redoing all of one's beautiful artwork and polygons. So, here is what I do. I can almost hear the screams from others that will say you should never intentionally destroy F/B annotation.

Here is the clue from HELP:

With active Forward&Back Annotation, no wires or vias can be deleted from a signal that is connected to components in a board. Also, no components can be deleted that have signals connected to them. Modifications like these have to be done in the schematic.
Use the RIPUP command to convert an already routed connection back into an airwire.

First recognize that some vias are optional and others are mandatory to meet design rules. An optional via is one that you may add between layers that is not required by DRC. Once that via is named with a signal, you cannot simply delete it. For example, if you are knitting two ground layers together, there may be no or only one required via. The others are optional. An example of a mandatory via would be one on a signal that goes to the bottom layer to cross under other signals. Deleting that via would lead to a layer change and no way to get from one layer to the other, which would interrupt the signal and will result in a board-schematic inconsistency. Eagle sees that interruption as a deletion or change to the schematic, hence the warning.

A simpler way for optional vias is to disable forward/back annotation by closing the Schematic. Then delete the optional via on the Board. Re-enable forward/back by clicking on the switch to schematic button and everything should be fine. Tested with 7.2.0 and 6.5.0 and had no problems with F/B consistency errors.

Now, what happens if you delete by mistake a mandatory via? You will get the dreaded warning that board and schematic are not consistent. At that point, you have two choices. You can continue to click away with rip-up until consistency is repaired. Or, you can replace the via exactly where it was, and consistency will be repaired. Obviously, when you are in the no F/B mode, only mess with the vias. I guess there are three choices, you can always save a back-up copy before venturing into the wild, but I never remember to do that.

John

 

Gracias ng and John for replying.

I was doing rerouting in the wrong way, forcing vias when changing layer. Now, I relearnt how to change layers while rerouting (leaving vias to pop up when Eagle finds necessary !!) so ripping up is, at least for now, the solution to my problem.