text: <s>[INST] PLC Firmware Revision Compatibility Issue. I'm facing an issue while trying to go online with a PLC. The firmware revision of the controller is 34.011, but the offline project I have is showing a firmware revision of 33.xx. Due to this mismatch, I'm unable to establish a connection. I'm relatively new to this company and recently learned that the program on my computer may have been modified by a contractor company, which might explain the version difference. I suspect they may have used a higher version of RsLogix when making the changes. I'm looking for guidance on how to proceed in this situation. Is there a way to update the offline project's firmware revision to match the controller's firmware revision? Or is there another solution to resolve this compatibility issue? [/INST] If you can't install v34 of Logix Designer then you cannot go online with the controller without wiping the project from the PLC, because you will have to change the firmware which will always wipe out the current project. If you can install v34 of Logix Designer, then the solution is simple, install it, upload the program. You can update the offline project file's firmware revision, but you need to have v34 installed. If you do, then go to controller properties and select Change Controller in the General tab. Change only the firmware revision, it will still ask you to upload when you try to connect though, so if you get v34 installed you might as well just upload the current project file from the PLC and ignore your offline file.\n </s>