How does communication takes place among modbus devices connected to various ports of BM 85 Bridge Multplexer. Specifically three modbus devices are connected to three modbus ports, one is master. Modicon Compact PLC is connected to Modbus lus port. How does the master device receives data and sends commands to the other devices. How a device is assigned as a master and how does master initiates communication? Does each register in the master to be assigned slave register address/s so that the communication takes place register to register? Is there any detailed document/paper available in this regard.