I am doing an upgrade on a plc implemented by someone else. The current systen is a PLC5/20E with 3 racks already defined. It also has a DH+ Network on Channel 1A. We are adding 2 Flex IO remote IO racks to it and adding multiple devices off of it. My questions is how to access the Flex IO addressing in the PLC5? Is it just another Chassis in the IO configuraiton? If so then I do not have enough rack numbers available since it is a PLC520. Any help would be greatly appreciated.