Whenever i tried to attach s7 300 siemens module to my pc it gives SF error , I,d checked system's plc inputs , hardware, motherboard, tested power supply by this method https://meterreviews.com/how-to-test-a-power-supply-with-a-multimeter/ , what more i should do to solve this issue.

 

What you mean by "attach" is that mean that you tryin to get communication betwee pc and S7/300 module...

if so did you either make the correct configuration for the communication as per this video :

Try to reply first on that question so we can give a better support

Cheers
Controls Guy25