Dear all, I am not able to find how to complie my programms ( in LAD ) in simatic manager step 7 v 5.4 ( the compile and download objects in PLc menu is in disabled mode !! ) and how to estabilish the communication with PLC ( i have s7 300 cpu313c) for downloading codes?? (the indication PC / PPI cable (PPI) is visible in the down status bar of simatic manager.) and in PG/ PC there is no MPI /PC driver also !! - i dont know detail sbout this I read the mannuals but still cannot find the result. Please help me to find a solution vikas