I am in the middle of doing a retrofit for a old PLC5 and i decided to upgrade it to a Control Logix. With how much I/O I was needing the price of the system was going to be very pricey. So I decided to use my main rack as a control logix and use Flex I/O for my remote racks. I have never put together a Flex I/O rack so I am unsure of what I need for this rack other than my I/O modules and a communication module. Could someone give me a list of what is needed for these systems?