The CP5512 is a PCMCIA card. Due to this I would not buy it from new. PCMCIA is a legacy standard that is disappearing fast from new laptops.
Consider the PC Adapter USB or the CP5711 USB in stead.
CP5512 and CP5711 can be used to troubleshoot Profibus networks to some degree, the PC adapter cannot.
The NetLink Pro is an Ethernet to MPI/DP adapter. You get all the advantages of ethernet. It cannot be used for diagnosing Profibus though.
Personally, I use ethernet enabled CPU's everywhere, so no need for any adapter at all. For the occasional need for programming an old CPU with only MPI or DP on board, I use a PC Adapter USB.