text: <s>[INST] What is the use of Program mode and Test mode over Run mode in rockwell  PLC. [/INST] Run mode is the normal mode of operation. Test mode is a version of Run mode. You can make online edits, Accept them, then go into Test mode and see if they work as expected. Then you have the choice to finalise and keep the new edits or to cancel them and revert back to the old version. In Program mode the code is NOT running. You can edit more easily than when you are in Run mode, and the changes are there in the processor without having to download. In Offline mode, you can edit freely and the changes need to be downloaded to the controller. \n </s>