Is here someone, who can advice me how to make a RS485 network at home, with Arduino prints and MAX485
i shall be 1 master and 7 slaves

 

There are several RS485 shields for arduino and many of them are open source with schematics available for download. You can buy the shields pre-made or you can rip off the design and roll your own. No need to design from scratch.

The network is simple. Put all the devices in parallel with a trunk cable with a 120 ohm resistor at each end. Cable should shielded twisted pair.

 

There is a basic choice you need to make early in the design process. Should the bus be a 2-wire bus or a 4-wire bus. With a 2- wire bus you will be limited to half-duplex communication. That is you cannot transmit and receive from a node at the same time. At ALL time a node is either transmitting or receiving, but NEVER both at the same time. With a 4-wire bus you can achieve full-duplex communication meaning you can transmit and receive at the same time