6.11.1 Forward annotation of lepton schematic changes to PADS PowerPCB layout

6.11.1.1 Overview

Forward annotation is the process of updating a layout to reflect changes made in the schematic. This process is used when, for example, a new component is added to a schematic and needs to be included in the layout. This section describes how to forward annotate changes in a Lepton schematic to a PADS PowerPCB layout.

PADS implements forward annotation through the use of an ECO (Engineering Change Order) file. The ECO file describes the differences between a current design and the desired design. PADS generates the ECO file by performing a netlist comparison between a new netlist file and the netlist contained in the current layout.

6.11.1.2 Detailed forward annotation procedure

This procedure assumes you have a board layout open in PADS and that you have made your schematic changes in lepton-schematic. For the purposes of illustration, assume your schematic is split into two pages in the files pg1.sch and pg2.sch.

original design to compareuse current PCB design
new design with changesmynet.asc
generate differences report
generate eco file
comparison options
compare only ECO registered parts
attribute comparison level
ignore all attributes

Click the ‘OK’ button to create the ECO file.