Terry (believe that was your first name),
I have never gone through the precise exercise of trying the premise
that you mention but it does sound very plausible to me from what I have seen.
I have looked at very similar Gerber data that seemed to have format
differences, while doing that I have seen differences in the ordering of Gerber
flashes and draws where the boards were identical in certain areas. I have also
seen PADs Gerber files where several revisions start out with precisely the
same draws or flashes, then a third version of the same board starts off with
draws and flashes in a different segment of the design. So your comments do
sound absolutely plausible to me.
We simply use Camtastic to do a lot of our revision compares. Loading
both the original revision and the new variation as overlays and comparing them
layer by layer. Not sure if the program you mention does anything more than
that, but highlighting the graphical differences for you. Of course both
mythologies fall down completely when there are significant changes/differences.
Sincerely,
Brad Velander
Senior PCB Designer
Northern Airborne Technology
#14 - 1925 Kirschner Road,
Kelowna, BC, V1Y 4N7.
tel (250) 763-2329 ext. 225
fax (250) 762-3374
-----Original Message-----
From: TDK [mailto:[EMAIL PROTECTED]
Sent: Saturday, December 03, 2005 9:53 AM
To: 'Protel EDA Discussion List'
Subject: RE: [PEDA] Importing Gerber Plot Files
Hi Brad;
When I was devising a methodology to compare gerbers on subsequent spins, so
I would NOT miss any detail, which has happened & required another spin,
several week delay & many perturbed managers & more $$$$, I thought of
comparing the data contents of the actual gerber file. Then I witnessed that
gerber files, if created from the exact same data, would NEVER be the same,
in data order that is. All is important is that the graphical end result is
the same, which it is. I don't want to propogate this theory if I am not 110
% sure & being accused of generating modern day PCB "wives tales".
Is this actually correct?
I have a nifty 3rd party file compare utility (Beyond Compare) which for $30
or so, is a great tool for comparing line by line & character by character,
BOM files.
What I end of doing now is using RSI VISION software which has a gerber
overlay / compare utility & shows the graphical DIFFS only. This works quite
well, but use a big monitor with very good resolution.
Regards
TDK
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