this gives null pointer exception when i use lib 1.2.9 but it works fine when i use 1.2.8.4,

[SanduDS]

/Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at com.intelligt.modbus.jlibmodbus.serial.SerialUtils.createSerial(SerialUtils.java:63) at com.intelligt.modbus.jlibmodbus.master.ModbusMasterRTU.(ModbusMasterRTU.java:34) at com.intelligt.modbus.jlibmodbus.master.ModbusMasterFactory.createModbusMasterRTU(ModbusMasterFactory.java:48) at powerMeterConnector.PMconnection.(PMconnection.java:43) / public class PMconnection { private static PMconnection plc; private ModbusMaster master;

public PMconnection() {
     SerialParameters sp = new SerialParameters();
    //Modbus.setLogLevel(Modbus.LogLevel.LEVEL_DEBUG); reading response
   try {

            String[] port_list =new SerialPortList().getPortNames();

        if (port_list.length > 0) {
          //  System.out.println("Port: "+port_list[0]);
            //set the compatible parameters for the PLC
            sp.setDevice(port_list[0]);
            sp.setBaudRate(SerialPort.BaudRate.BAUD_RATE_9600);
            sp.setDataBits(8);
            sp.setParity(SerialPort.Parity.EVEN);
            sp.setStopBits(1);
            //if(master==null){ //singleton (not the correct)
                master = ModbusMasterFactory.createModbusMasterRTU(sp);
          // }

        }
    } catch (RuntimeException e) {
        throw e;
    } catch (Exception e) {
        e.printStackTrace();
    }

}
public static PMconnection getInstance() {
    if(plc==null){
        plc=new PMconnection();
    }
    return plc;
}
public ModbusMaster getMaster(){
    return master;

}

}

[SanduDS]

please tell me what I got wrong. and power meter (SMD 220 eastron )gives me integer register values but I couldn't convert it to real values. I m new to Modbus

[kochedykov]

Hi! JLibmodbus supports several uart connectors like jssc, rxtx, jserialcomm etc. Before you create a master you should set SerialPortFactory, for instance jssc: SerialUtils.setSerialPortFactory(new SerialPortFactoryJSSC()); If you need to read float values you can use the code below:

        ReadHoldingRegistersRequest request = new ReadHoldingRegistersRequest();
        //Or ReadInputRegistersRequest request = new ReadInputRegistersRequest();
        request.setServerAddress(slaveId);
        request.setStartAddress(offset);
        request.setQuantity(2);
        ReadHoldingRegistersResponse response = (ReadHoldingRegistersResponse) 
        request.getResponse();

        master.processRequest(request);
        ModbusHoldingRegisters registers = response.getHoldingRegisters();
        registers.getFloat32At(0);