Page 236 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards

window from which the ULP has been invoked is actually a schematic. You will find this in the
following line, halfway down the program:

If you mentally close off the braces to find the else condition for this, you will find the following
lines right at the end of the file:

This displays a dialog window telling you that you are not in a schematic window.

Assuming that the ULP is being run in a schematic window, we now have a chunk of code that
iterates over the schematic in a hierarchical way constructing the command to be run. This uses a
syntax that names an object in the design’s internal model and then a variable that can be used to
access all instances of such objects. For example,

All the code inside the curly braces will be repeated for each schematic, and the schematic whose
turn it is can itself be accessed using the variable S. There is only one schematic, so this syntax makes

more sense if we look a bit further down the program, where every sheet of a schematic is iterated
over and then within that every part on every sheet using

Summary

In this chapter we have looked at using scripts and ULPs to automate activities in EAGLE. The
EAGLE ULP manual is some 130 pages long, so we have only really scratched the surface of the
language. You can find out more about it at ftp://ftp.cadsoft.de/eagle/userfiles/doc/ulp_en.pdf. You
will also find a reference for ULP in Appendix C.

In Chapter 11, we will return to libraries and learn how to modify and create our own libraries
and parts.