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Read more than a register in one request


  • Hello guys,
    I'm newbie in industrial field, my background is an IT, I need to use Modbus4j; I have one problem, I think it is easy to solve for you guys,

    I need to read more than one register in one Modbus request as part of the modbus standard, can I do that without changing the code?

    for example:
    I need to send Modbus request to a slave id, with range (4001 Holding register), with offset 3* and length 6 (6 registers)*

    Thanks


  • hi bkhashfeh
    yes its possible to read more than one register in one request. for detail please post your example code i will suggest u corrections in your code.

    regards

    mahesh


  • Hi, I'm not bkhashfeh but I have the same problem and I'd apreciate the help :D . Here is my code where I'm reading three registers per second (or trying).

    package modbusmastertest;

    import com.serotonin.modbus4j.ModbusFactory;
    import com.serotonin.modbus4j.ModbusMaster;
    import com.serotonin.modbus4j.code.DataType;
    import com.serotonin.modbus4j.ip.IpParameters;

    import java.io.FileWriter;
    import java.io.PrintWriter;
    import java.util.Calendar;

    class MBMasterTest {
    public static void main(String[] args) throws Exception {
    // Modbus master settings
    ModbusFactory factory = new ModbusFactory();
    IpParameters params = new IpParameters();
    params.setHost("192.168.0.1");
    params.setPort(502);
    params.setEncapsulated(false);
    ModbusMaster master = factory.createTcpMaster(params, false);
    master.setTimeout(333);
    master.setRetries(1);
    // CSV writter settings
    FileWriter fwriter;
    fwriter = new FileWriter("C:/Users/NESTOR/Dropbox/Siemens_S7-1200.csv");
    PrintWriter outputFile = new PrintWriter(fwriter);
    outputFile.println("Date,Sensor_1,Sensor_2,Sensor_3"); // Primera línea
    Object []Register = new Object[3];
    // Date settings
    Calendar cal = Calendar.getInstance();
    long elapsedTime = 0;
    long time = 0;

    	    // Cuerpo del programa
    	long start = System.currentTimeMillis(); // Tiempo de inicio
    	try {
    		master.init();
    		while(System.currentTimeMillis()<(start+10000)) {
    			time = System.currentTimeMillis();
    			for(int i = 0; i<3; i++) {
    				Register* = master.getValue(1,40001+i,DataType.TWO_BYTE_INT_SIGNED);
    			}
    			System.out.println(Register[0]+","+Register[1]+","+Register[2]);
    			System.out.println(""
    					+ "");
    			elapsedTime = System.currentTimeMillis()-time;
    			cal.setTimeInMillis(cal.getTime().getTime() + elapsedTime);
    			outputFile.println(cal.getTime().toString()+","+Register[0]+","+Register[1]+","+Register[2]); // Se escribe nueva linea en archivo
    		}
    		outputFile.close(); // Se cierra el archivo
    	}
    	finally {
    		master.destroy(); //Se destruye el objeto master
    	}
    	
    	System.out.println(""
    			+ "");
    	System.out.println("Tardo " + (System.currentTimeMillis()-start) + "ms");
    
    }
    

    }