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We are using EM6436 energy meter connected to a PC via RS232 to RS485 converter.

With my own code using modbus4j open source library,we are able to discover the Energy meter and obtain its ID using Modbus4j.
But when I try to read data address (3901 say) of the device(EM6436) using the following code:

  			SerialParameters params = new SerialParameters();
 params.setCommPortId("COM1");
 params.setBaudRate(9600);
 params.setDataBits(SerialPort.DATABITS_8);
 params.setParity(SerialPort.PARITY_EVEN);
 params.setStopBits(SerialPort.STOPBITS_1);
 ModbusMaster master = null;
 ModbusFactory factory = null;
 try
 {
  factory = new ModbusFactory();
				master=factory.createRtuMaster(params, 0);
 if (master == null){
 	return;	
 }	
  master.setTimeout(5000);
  master.init(); 
  Object obj = null;
  NumericLocator locator = null;
 try{
  locator = new NumericLocator(1,
   RegisterRange.HOLDING_REGISTER, 3901, DataType.FOUR_BYTE_FLOAT);
 obj = master.getValue(locator);
				
  }catch (Exception e) {
	 System.out.println("Exception occured : "+e.getMessage());
  }
				
 System.out.println("Value read"+"for------"+i+"----------->"+obj);
			
  }
  }  
 finally { 
	   master.destroy();  
  }  
 } 

We are getting error as Error Response Exception :Invalid data address or sometimes its giving TimeOut exception.
The same code is working fine with the simulators (Modbus PAL , Modbus PLC).

Even reading the same data address with ModScan32 (with the same connection) is also working but not with the above code. Please suggest.