Elementary OrCAD question

[silverfox]

I just started with OrCAD and I have been doing pretty well with the
help of a book by Kraig Mitzner. But I can't find the way to do a
very simple task that must be too obvious to include in the book. At
least I couldn't find it.

Anyway, I now have a design that I created with Capture and a
corresponding layout that I built in Layout. But now I want to
change the value of a resistor. I can do it in Capture and the change
shows up correctly on the schematic. But I haven't been able to
figure out how to export the change to Layout without starting all
over from scratch in Layout. Everything I try has no effect on the
value of the resistor in the various reports. What am I missing?

 

[[email protected]]

I just started with OrCAD and I have been doing pretty well with the
help of a book by Kraig Mitzner.  But I can't find the way to do a
very simple task that must be too obvious to include in the book.  At
least I couldn't find it.

Anyway, I now have a design that I created with Capture and a
corresponding layout that I built in Layout.   But now I want to
change the value of a resistor.  I can do it in Capture and the change
shows up correctly on the schematic.  But I haven't been able to
figure out how to export the change to Layout without starting all
over from scratch in Layout.   Everything I try has no effect on the
value of the resistor in the various reports.  What am I missing?

It should just be a matter of choosing the correct type of ECO that
you run.
The obvious question is does it really matter. For instance you do not
want to go through this each time you have a BOM change. Assuming a
commercial situation, you want to archive layout at the time you
create the gerbers and have the production people modify their
spreadsheet/database as required.
Colin

 

[silverfox]

It should just be a matter of choosing the correct type of ECO that
you run.
The obvious question is does it really matter. For instance you do not
want to go through this each time you have a BOM change. Assuming a
commercial situation, you want to archive layout at the time you
create the gerbers and have the production people modify their
spreadsheet/database as required.
Colin

Yes it matters because I am ready to send the board to the
assemblers. Could you elaborate on your answer? I don't know what
you mean by running an ECO or running the right type of ECO.

 

[Ned Forrester]

I just started with OrCAD and I have been doing pretty well with the
help of a book by Kraig Mitzner. But I can't find the way to do a
very simple task that must be too obvious to include in the book. At
least I couldn't find it.

Anyway, I now have a design that I created with Capture and a
corresponding layout that I built in Layout. But now I want to
change the value of a resistor. I can do it in Capture and the change
shows up correctly on the schematic. But I haven't been able to
figure out how to export the change to Layout without starting all
over from scratch in Layout. Everything I try has no effect on the
value of the resistor in the various reports. What am I missing?

After changing the schematic in Capture to have the new value, create
the netlist again, the same way you did the first time. Then in Layout
select Tools->Auto ECO (I use an old version of layout, 9.0, I think, so
things might have changed some). This will compare the new netlist with
the data in the .max file and make any necessary changes. The new
component value should now show up in the layout.

In Orcad, there is no automatic connection between Capture and Layout.
Layout learns what happened in Capture though the netlist, and Capture
learns what happened in Layout through the back-ECO file (this is
optional, it is not necessary to run Back ECO, unless you do pin-swaps
in layout or want to export constraints back into Capture; usually I
only go forward and not backward).

--
NOTE: to reply, remove all punctuation from email name field

Ned Forrester [email protected] 508-289-2226
Applied Ocean Physics and Engineering Dept.
Oceanographic Systems Lab http://adcp.whoi.edu/
Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA

 

[[email protected]]

Yes it matters because I am ready to send the board to the
assemblers.  Could you elaborate on your answer?  I don't know what
you mean by running an ECO or running the right type of ECO.- Hide quoted text -

- Show quoted text -

No, you have missed the whole point. You should not use files created
by layout to define your BOM. If you had seven different versions of
your product (different size FPGAs, different memory options, features
not fitted at all.... whatever) you would not create seven MAX files.
If you find a design error what are you going to do, create seven new
MAX files? Create your PCB, generate all outputs from the MAX file,
ZIP up the max file and a copy of all output files in a zip file
clearly marked as "issue 1" and NEVER TOUCH IT AGAIN. Create your BOM
in excel or a decent database program and modify that to create your
seven builds. This is what your assembler will expect. He will not be
even slightly interested in the fact that your component placement
file says that R1 is 100R instead of 150R, he will cross reference R1
to his stock control system via the BOM that you send him.

Colin

 

[qrk]

Yes it matters because I am ready to send the board to the
assemblers. Could you elaborate on your answer? I don't know what
you mean by running an ECO or running the right type of ECO.

Look in the manual or help file in Layout regarding ECOs. Look up "ECO
command" in the program help. I think you want AutoECO/Override All.
You should be giving your contract assembler a BOM generated from
Capture which is considered the bible for your assembly.