Here's my test program screen:
The "LED"'s on the screen actually read back from the outputs of the PLC itself. That way, if anything happens locally at the PLC, or if there is an error, this can be quickly diagnosed on the main Gravesend control screen.
I always start with this kind of stuff by writing a stand alone test program, and then, once that's debugged, bring it into the main Gravesend Inn program. I also wrote a sequence that's firing each relay in sequence and letting this (and the associated output polling) run all night. I always do this to look for overrun errors, etc. Generally, after going through a process like this, integration with the main program goes pretty smoothly.
So, success, and it's Friday, off to the pub!