question: public void readData ( DataInput din ) throws IOException { din . readShort ( ) ; count = din . readUnsignedShort ( ) ; registers = new InputRegister [ count ] ; for ( int i = 0 ; i < count ; i ++ ) { registers [ i ] = new SimpleInputRegister ( din . readShort ( ) ) ; } }
target:  readData -- input the Modbus message from din. If there was a header, such as for Modbus/TCP, it will have been read already.