Connect to your PLC, and visit the I/O Configuration window for full Auto-Discovery of your modules in the local or remote base (remote I/O auto discovery only available with DMIO and EBC100 remote base controllers).
Each new I/O module connected will be autoconfigured in the software and ready to use in your program.
Manual configuration of your Do-more option modules is also possible, and offers one very interesting possibility...
If the I/O Master's Configuration Mode is set to "manual", you can mark a module as Optional - meaning that it will not be considered when the I/O configuration is read from the system during a Program-mode to Run-mode transition (i.e. you won't get any errors if the module is missing).
Here's the best part: you can then use the HWINFO (Get Hardware Information) instruction to detect the presence of I/O modules marked as 'Optional' as a way to programmatically control optional execution schemes.
Note: I/O modules that are configured as optional will be marked with the word "*Optional*" in yellow on the graphical view in the I/O Configuration window.