Serial Communication

Hii,

I want to establish serial communication between Microcontroller: ATmega328 and Siemens PLC S7 300.

I am using RS 485 for serial communication.

Where can I find important information?

I tried to google it but cant find any proper info

Thank you

For the Arduino side of things, read Serial Input Basics - updated.

For the PLC, consult the documentation or contact Siemens.

Sanjay26121990:
I tried to google it but cant find any proper info

Well, Google shows a lot of relevant information and examples for RS-485 and Arduino. What exactly are you trying to find?
There seems to be a lot of documentation available on Siemens' site, the protocol and connection diagram have to be somewhere in there.