craigmw,
There a couple of option settings that the Python interval program does not use including the port number and rain sensor related settings.
I included them to maintain compatibility with the Arduino based micro controller version of the program. They could be implemented in the future.
I have been thinking about making the port number functional but it would probably require some operating system level code and that would add to the complexity of the set up.
Changing the expansion board number does cause the snames.txt file to be re-written as you discovered.
I will include that in a trouble shooting section of the documentation that I am working on for the wiki.
At this point the wiki page is located at:
http://rayshobby.net/mediawiki/index.php?title=User:Dan_in_CA
but it is not yet listed in the navigation pain for the wiki. I think Ray would need to add it there.
EDIT:
The documentation for the Python interval is now located at:
http://rayshobby.net/mediawiki/index.php?title=Python_Interval_Program_for_OSPi
and can be accessed through the wiki menu under OpenSprinkler Pi.
Dan