RS485 Master and Slave using Modbus

I am trying to find a simple example of using Modbus to link several Arduino Boards, simply sending digital and analogue signals from the Master to each Slave.  Modbus seems overkill but the application involves large distances outdoor lighting.  I have worked through the tutorials:

Long Distance Wired Serial Communication with Arduino using RS485 and CAT Cables

I have made this work but this only works for one Slave

RS-485 MODBUS Serial Communication using Arduino UNO as Slave

[original story: Circuit Digest]

Circuit Digest 08 Oct 21:24