I suggest you to use the OpenSprinkler web UI in a browser, open a developer tools window, then create a program, and take a look at the ‘Networks’ tab of the developer tools window. It shows the exact command /cp that’s sent to the controller. That way you can see exactly how each variable is set.
About expander: you need to enable all 24 zones in Edit Options -> Station Handling, set the number of zones/stations.