DriveTop works on DIAX03, DIAX04, and of course, the new IndraDrives.
You can think of Synax another way. If it has to do with the SERCOS ring, you need Synax. If its just drive parameters, DriveTop. The kicker is that _almost_ anything you can do with DriveTop, you can do with Synax.
Inside a PPC, there's also the possibility of one of two different programs running, the ML (Motion Logic), or M(I don't remember) for the SYNAX I/O mapper.
I/O mapper has very limited logic, and basically connects drive status and command bits to other bits.
Motion Logic is a verson of CoDeSys programming, to the IEC 61131 standard, and very powerful.
One other thing....each drive has a firmware module, matched to the application, and the drive configuration.
Each PPC also has a firmware module, depending on the industry, and choice of Motion Logic or Mapper (you can't have both).