When wanting to add a PLC to TIA Portal, there are a few different options to consider.
The version of Step 7 you have, Basic or Professional, determines which PLCs can be added to a project.
Basic will only allow the S7-1200 Family, while Professional will allow the S7-1200, S7-1500, S7-300, S7-400, as well as the ET200SP 1500, and software controllers.
There is the traditional way of adding in a PLC in the project by going through the hardware catalog and selecting the right part number based on the part number of the device. This can be cumbersome if the PLC is already in the cabinet or if there are multiple I/O cards and other peripherals.
The easiest way to add a Siemens PLC to a TIA Portal project is with the Detect feature. Using Detect, you can add a blank PLC to the project. Ensure that your engineering station is connected to the PLC via profinet and then hit detect. TIA uses the MAC Address of the PLC to locate and identify the PLC and all I/O cards that are included.
Once the PLC has been added to the project, the IP address can be assigned from the properties tab as well as give a Profinet Name. After you have completed this, save the project, compile, and download it to the PLC.
If a user wants to connect and download from an existing PLC in the field, they will still go about the same process of adding the PLC to the project as before. Either with detect or handpicking all the components from the hardware catalog.
Once that is complete, rather than assigning an IP address and downloading to the PLC, instead go online with the PLC and upload the program from the PLC to your engineering station. This is useful for creating a backup of an existing program, or making sure that the user is working on the latest version of the program by getting it directly from the PLC.
If there are multiple PLCs in a cabinet, it can be confusing to ensure that you are selecting the correct PLC unless you plug directly into that PLC. This cannot always be done, especially if they are daisy-chained. More than likely, they will have an ethernet cable run back to a network switch, and that is where you will have to make your connection to the engineering station. When you are attempting to go online and connect to the PLC, there is a Flash LED feature in Step 7 that will allow the user to connect to a PLC and then make all the lights flash on the front of the PLC. This is great to make sure that the preferred PLC is selected. This feature also works on drives and HMIs.
With the detect feature and the ability to add multiple PLCs in one project without having to open multiple instances, TIA Portal makes it easy to commission and troubleshoot your automation system all in one spot.