Elementary OrCAD question

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?

Reply to
silverfox
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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

Reply to
colin_toogood

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.

Reply to
silverfox

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).

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Ned Forrester        n_f_orrester@whoi.edu         508-289-2226
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Reply to
Ned Forrester

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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

Reply to
colin_toogood

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.

Reply to
qrk

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