There is also a V15 Pro COMBO license that allows you to use (on the same computer) v5.6 and V15. It also doesn't support things like 300T or 400H.
This means a lot of legacy equipment isn't supported. Note that it does have a HW cutoff: I think it only includes HW that was current as of 2007 or newer. Step 7 V15 Basic covers the 1200s, and also includes WInCC Basic for the Basic line of HMIs. Pro is a bundle of a few packages together (Step 7, PLCSIM, SCL, Graph). There is no BASIC version, there is 'regular' or Professional. Step 7 V5.6 covers the older 300/400 processors, and their variants (WinAC, ET200S, etc). Step7 V15 Professional can program all PLC's, but offers nothing extra over the V15 BASIC if one plans to use v5.6 for the other PLC's anyway. My understanding is that v5.6 will program 300, 4 PLC's, and the V15 (TIA) is needed only for the 1200 PLC's. So I'm planning to get the Step7 v5.6 BASIC and the Step7 V15 BASIC.
Due to all the (still) missing basic functionality in V15 (TIA), I don't plan to start using it any sooner than I have to.
