doug,

It seems to me your customer is asking for a "diff" of the gerber files.
I think you are right, the engineer should be able track the net list 
changes, this should be a function of the schematics.  I would think
if the engineer can provide a net list with all the changes then you 
would be in business. BUT, this doesn't help you in you current situation.     

Can you do a "diff" on the net lists ?   Or write a script to do the same.
Are you on UNIX or windows ?

There is one other way that I know of that might help you,  ADI Pro-Circuit 
Builder is a gerber tool with intellegence.  It is able to read a net list 
and compair it to the gerber database.  It seems a powerful tool to me. 

I think this could help you find the differences in the two revisions of 
a board.  ADI reads both the gerber files and a net list. To find the 
differences you could provide the gerber files for the current board, 
along with the net list from the old one.  This should produce a list of 
differences.  You would need to call them to find out if it can do all
the stuff you'll need.  

Contact:
Robert Lowry
ADI
703-742-9400x21

Automata, in Sterling Virgina, a board shop, uses this tool.


let me know how it works out.
joez



> 
> We are an independent Service Bureau
> 
> A year ago we completed a board for a customer. The board had
> roughly 7200 individual nodes. Recently the customer asked
> us to incorporate revisions affecting approx 500 of those nodes
> (some parts deleted, several new parts + other changes.) 
> 
> Revisions are, of course, dynamic, so we received approx 4 up-dated
> net lists during the process. The problem is that he had numerous
> unnamed nets. The schematic capture system would assign random names
> to those nets each revision. Our system doesn't care if names change
> as long as the integrity of the overall net list is preserved. 
> 
> When we gave him the check plots he asked us for a printout of 
> just the changes, presumably so he could check just those. Since
> most of the nets were renamed several times,
> we didn't see how we could meet his request, but he insists that we
> should be able to. 
> 
> So I'm looking for your input.
> 
> 1. Isn't it the engineer's job to keep track of changes if he wants an
> audit trail? 
> 
> 2. And isn't our job to implement them and create a design that matches
> the netlist that he says is the final and correct one, but not to maintain
> his audit trail of changes? (in particular, a "net-diff" list from two
> net lists with randomly assigned net names?)
> 
> 3. If a schematic capture system assigns names to the nets, isn't there
> a way to fix those assignments and make them permanent?
> 
> I'm not looking for sides, here, but a way to see this problem coming
> and be able to solve it next time.
> 
> Thanks for any input
> 
> Doug Brooks
> 
> 
> 
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