User Macro B will afford some solutions.
#3001 is the system timer
put this at the beginning of your part program
#3001 = 0 (reset timer to 0)
put this at the end of your program
#500 = #3001
When the machine stops cycle, your operator will go over and read the value stored in Macro Register #500 and that is your most current cycle time.
User Macro capability would allow more sophisticated programming and hook up of a light, but that stuff is far beyond what I know how to do! I only know it can be done, if you have an electrical/computer programming person available.
User Macro Capability exists, in part, to offer the machine builder to make solutions to situations similar to yours. programmingunlimited.com has a great user macro book, but it's more for programming than interfacing devices. There's other materials out there, also.