Hi Cosgrove, 

Thank you for reaching out. The answer to this question depends on what you are trying to achieve with your application. The below diagram from RS-485 Basics Series shows the typical RS-485 (half-duplex) bus that is sending to several nodes. This is configuration would be capable of "splitting" or sending the signal to 8-separate nodes since each node will receive the message on the bus. Without the complexity of a daisy chain or repeater. 

Let me know if this works for you.

Best,
Andrew

cosgrove wolde said:

I m configuring RS485 as full-duplex, what would be the connection? 

Full duplex would be the configuration shown below the one in the blue box. 

cosgrove wolde said:

ISO3082 for both master and slave that is 9 pcs of IC chips, do you any schematic diagram to offer? and do you see any schematic and PCB layout issues and concern to take note of?

• The EVM, ISO485EVM Evaluation board | TI.com, shows the common layout recommendations for a single transceiver. 
• TIDA-01281 reference design | TI.com - is a reference design that shows common isolated protocols with an MCU

cosgrove wolde said:

how could i do handshaking between master and the 8 slave RS485? I read from TI notes, it is the CTS and RTS line? Any suggestion and app notes to offer ?

Handshaking between the master and slave nodes will be completed by the MCU's and not on a hardware level. Usually, the slave has an address or only responds with data when the master controller requests data. TI makes the transceivers for the physical layer. The data is defined at the MCU communication level is defined by several different protocols. There are a few of these network level standards, one is described here: PROFIBUS Electrical-Layer Solutions (Rev. A).

Also, CTS and RTS refer to the RS-232 protocol which is a different physical layer and standard.  

Hello Cosgrove, 

As discussed, RS-485 only uses an A/B differential line to communicate between a master and multiple slave nodes. Each node on the bus will see the same signal. The ISO3082 will interface with the bus (receive and transmit messages) to a local microcontroller.

The slave nodes are commonly programmed with a unique ID (or address) and only transmit on the bus when their address received by the master controller. Only one node can be controlling the bus at a time. Interaction between multiple slave nodes is handled by the master controller using a communication protocol that is programmed into each MCU. The ISO3082 will only interface with the bus on an electrical (physical layer).

It is up to your application do decide which RS-485 -based communication protocol is used. 

RS-232 is a completely separate physical layer that uses a clock and several datelines to communicate (CTS and RTS are 2 of these lines).  

Best,
Andrew