Airwires

Am 15.07.2016 um 16:47 schrieb Steve Kale:

Hi

 

I have been laid low by a board which passed DRC and ERC (board and circuit were the same) but which had an uncompleted trace - an airwire.  I am very surprised that DRC/ERC didn't flag this up.  I see now that when I run the rats nest tool it will tell me how many airwires remain but of course it doesn't tell where they are.

 

Are there any tips to avoid such problems in the future?

 

Regards

 

Steve

 

--

To view any images and attachments in this post, visit:

https://www.element14.com/community/message/201504

 

RATSNEST and DRC are two separate things. There are intentions to

show the number of airwires also when checking for errors.....

Basically you should always do a RATSNEST when you think you have

finished your design. Of course, you should use RATSNESt also when you

are working on the layout. So the airwires will be recalculated and

you have also options to hide signals for the routing process

--> HELP RATSNEST for more...

If you are searching for the left airwire in your design you could

go to Options/Set/Misc and set the "Catch factor" to 100%.

Now WINDOW FIT; , activate the ROUTE command and click into the

drawing. The airwire will be catched by the mouse cursor.

--

Mit freundlichen Gruessen / Best regards

Richard Hammerl

  CadSoft Support -- hotline@cadsoft.de

  FAQ: http://www.cadsoft.de/training/faq/

Thanks for the tips regarding searching for airwires.  I still find it rather extraordinary that airwires don't produce DRC/ERC errors and that the board and schematic can be regarded as consistent when there is incomplete routing.  Doesn't make any sense at all.

Steve Kale wrote:

 

Thanks for the tips regarding searching for airwires. I still find it rather extraordinary that airwires don't produce DRC/ERC errors and that the board and schematic can be regarded as consistent when there is incomplete routing. Doesn't make any sense at all.

Hi Steve,

An air wire isn't a error, it's just a net you haven't routed yet therefore the schematic and layout are consistent regardless of whether it's been completely routed. An example of it being inconsistent would be if you changed something in the schematic without the layout being loaded so it didn't reflect this change, then they are inconsistent. I'd be happy for DRC to add a note (not error) reporting the number of air wires remaining but it's so quick to hit "Ratsnest" that it's really not an issue for me.

A better place to show a more obvious message would possibly be in the CAM processor if you were trying to export gerbers when the routing was incomplete. It's fine to do this if you just want a quick ballpark quote but I can see it being useful for some people if it were highlighted at this point. All these issues can easily be solved by having a simple pre-manufacturing checklist which you complete before submitting your final data to the board house though.

Best Regards,

Rachael

Steve Kale wrote:

 

Thanks for the tips regarding searching for airwires. I still find it rather extraordinary that airwires don't produce DRC/ERC errors and that the board and schematic can be regarded as consistent when there is incomplete routing. Doesn't make any sense at all.

Hi Steve,

An air wire isn't a error, it's just a net you haven't routed yet therefore the schematic and layout are consistent regardless of whether it's been completely routed. An example of it being inconsistent would be if you changed something in the schematic without the layout being loaded so it didn't reflect this change, then they are inconsistent. I'd be happy for DRC to add a note (not error) reporting the number of air wires remaining but it's so quick to hit "Ratsnest" that it's really not an issue for me.

A better place to show a more obvious message would possibly be in the CAM processor if you were trying to export gerbers when the routing was incomplete. It's fine to do this if you just want a quick ballpark quote but I can see it being useful for some people if it were highlighted at this point. All these issues can easily be solved by having a simple pre-manufacturing checklist which you complete before submitting your final data to the board house though.

Best Regards,

Rachael