[PCB_FORUM] Re: ECAD Property

Hi Don,
 
The "Best Practices paper" you are refering to is based on a white paper
I rpesented at ICU2003 and I am in the middle of revising it's content.
The plan is to present at CDNLive 2007. The process you outlined below
is right on the mark and, no you don't have to set the IDF_OWNER
property for all non-MCAD tagged parts.
 
The Translator in Allegro is smart enough to not move parts that don't
have the IDF_OWNER set to ECAD. As a matter of fact it will never move
any ECAD parts unless Cadence is changing the code.
Your ME's don't have to do anything either. The IDF file from ProE will
set the placement tag to PLACED. The IDF import in Allegro translates
this to MCAD. I know, I know ... ProE should set this to MCAD, but it
doesn't and from
a flow perspective, the implmentation in Cadence works well. Unless it
says UNOWNED, if it doesn't say ECAD it must be MCAD. There
Ownership/Action table in the paper you mentioned.
As with any software company there, if you think it's wrong, well call
TechSupport or your respective AE ;-)
 
One other note on the moving topic. MCAD tagged parts are fixed in
Allegro, so you can't just move them. Back in 15.1, when the translator
was introduced in Allegro it required 5 mouse clicks to unfix the part,
so if some one
moved it, well they didn't on purpose. Today, 15.2 and beyond, Allegro
as this great "unfix" button in the menu which kind of defeats the
purpose of fixing the MCAD parts. I think Allegro shouldn't allow a move
action on objects that have the IDF_OWNER set to MCAD. But then on the
other hand ProE is just storing the Ownership attribute on the parts and
doesn't pay much attention to it either, so at the end of the day you
will need a process and verification tools
to make sure things don't get out of hand.
 
Hope this helps
 
Andy
Senior Applications Engineer
www.ptc.com
 
<Don wrote>
Let me re-phrase the question and add an example of the behavior that we

are seeing.
Here's the scenario:
1. read netlist into board
2. read in IDF from Pro/E  to get board outline and place critical parts
3. complete a rough placement of other non critical parts in Allegro
4. export IDF to Pro/E 
5. continue to fine tune placement of non critical parts
6. receive a new IDF from PRO/E with critical parts moved
7. after reading in IDF critical parts move as expected, but other non 
critical parts move back to their rough placement position.

After reading through the IDF documentation, it would appear that since 
the non critical parts are not specifically owned by ECAD, that the IDF 
interface sees the difference between the MCAD and ECAD placement, and 
takes ownership of the non critical parts and moves them back to their 
original position. So it would seem to me that we need to explicitly
take 
ownership of all the non critical parts in the design so that these
parts 
will never move when an older IDF file is read in.
The mechanical guys tell me that it's too painful export only the parts 
that have changed, and so they export the entire design. So given this 
scenario, should we be setting the ownership to ECAD, to stop any
unwanted 
part movement?
Don ...........................

 
Andreas Kulik 
Senior Applications Engineer
I*Center East
PTC
781 370 5893


 

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