Got a problem with the loss of output data file configuration for analog input modules on download for a A-B SLC 500. Its happened to me a couple times, i saved the program while online then went offline made some changes that had nothing to do with the analog modules. After downloading the edited program i had to reactivate the analog input modules output data files. This has happened on two seperate plc's. I didn't clear the processor memory before downloading not sure if thats what caused the problem.