On 04:03 PM 12/07/2001 -0400, [EMAIL PROTECTED] said:
>Protel is doing its job.  I'm looking for a better way to do my job.
>
>I have a footprint which performs as a jumper for me.  That is, two pads
>connected together by a trace.  My schematic symbol for this part is two pins
>with different numbers.
>
>When I run a DRC on the board, Protel sees these pins shorted by the
>footprint and generates errors because the schematic doesn't have the two
>pins connected.  In fact, it generates Short Circuit and Clearance Constraint
>errors for each part.  I'm forced to sort through each of these errors.  It
>takes time and I risk the possibility of missing a real problem.

The Lomax (tm) Virtual Short will work for you.

Make a very small gap in the tracks within the jumper component.  Put a 
square fill on the end of each track and have a space of bugger-all, say 
0.05 mil, between the fills.  This is too small to manufacture and so will 
appear as a short of the final board.  Add a clearance design rule for that 
component (or that footprint specification if you have more than one of 
these on your PCB) that allows clearances of 0.01mil.  Then everyone should 
be happy - you have your short, Sch has two separate pins, DRC is convinced 
it has you under control.

Works well for us.  There have been some recent reports that depending upon 
gerber resolution settings there may be some worrisome round-off issues but 
I have never seen these.  It is also advisable to make mention of what you 
are doing in manufacturing notes so that the person setting up the CAM info 
when the board is made understands that it is not an error.

The main problem I have with using the Allow Short-Circuit design rule is 
that the allowed rule scopes do not include region or other restrictive 
scopes so that you cannot be sure the short occurs in the area you 
want.  Since it can't do this I have never investigated if the rule 
actually works.  I for one have been asking for better scopes on the Allow 
Short Circuits rule since the very first time Protel introduced the rules 
based system.

Ian Wilson

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