RSLogix 500 8.1 uses (FTAct) for licensing. Install it first (it’s often on the same DVD or can be downloaded separately from Rockwell).
Added Modbus RTU Master support for SLC 5/03, 5/04, and 5/05 controllers, facilitating easier integration with third-party devices. Security Adoption:
: You must have a free Rockwell Automation Account to proceed. If you don't have one, you will be prompted to create it before downloading.