Definitely placement file is generated from Layout through Tools ---> Basic Scripts ---> Basic Scripts with the help of script .
But when a component value is changed is schematic or interfaces are removed , ECO is to be done from LOGIC to LAYOUT to actually undergo the change done in logic into the layout .
Change in component value is done in logic but the PCB Decal will remain the same for such components as the package remains the same .
Also layer is not added into the CAD library for any of the components . Part is always created in CAD library for TOP layer .
Attribute for layer is not added in part attributes .
For example ,
R1 is open components and is on Top Layer and R2 is Short and is on bottom .
Now when we change R1 to short and R2 to open and generate placement data then placement file shows the wrong information for layer .
That is R1 which is on top will come on bottom and R2 which is on bottom come on top even if the components are placed on same layer before the change .
This result comes with the ECO Names ' Compare Names and Rename Nets and Parts as Necessary'.
But when we first ECO with the ECO Names 'Compare Names but Prefer Add/Delete Parts to Renaming ' then placement data is generated correct .
So please assist .
Best Regards ,
Parth Sutariya
Hardware CAD Engineer
MATRIX COMSEC
Vadodara , Gujarat
INDIA