If you work in industrial automation, you know the pain. You open a .ACD file, and the pop-up hits: "This file was created with a newer version of RSLogix 5000." Or worse: "You cannot open this file because it requires an older revision."
What is the processor part number?
RSLogix 5000 v20.06 is the best choice if: rslogix 5000 version better
If you are buying a new CompactLogix 5480 or a ControlLogix L85E, you cannot use v20. You need v32 or higher. The "better" version here is v32.03. The Ultimate Guide: Which RSLogix 5000 Version Is Better
For Older Systems: Use v20.04. It is the most stable and compatible version for legacy installations that haven't migrated to newer L8x processors. Status: Legacy / End of Support
Rockwell allows you to install multiple versions on one PC. Most field engineers have every version from v13 to v35 installed to ensure they can connect to any PLC they encounter. Final Verdict For Legacy Systems: Stick with For Modern Projects: v33 or v35 for the best balance of features and long-term support. controller model are you currently looking to program or upgrade?
Not every update is an improvement. Some versions are known for specific "features" (bugs) that can be disruptive: