The "PC/PPI Cable (PPI)" interface cannot be installed in "Set PG/PC interface"
Why can't I install the "PC/PPI Cable (PPI)" interface in "Set PG/PC interface"?
You have installed STEP 7 V5.1 / SP2 alongside an existing installation of STEP 7-Micro/Win32. Now you want to add the "PC/PPI Cable (PPI)" interface via "Start > Settings > Control Panel > Set PG/PC interface > Install". But it is not possible to insert the interface.
Install STEP 7-Micro/Win32 V3.1 with SP2.