I have a problem - Exception in thread "main" com.ghgande.j2mod.modbus.ModbusIOException: I/O exception - failed to read at com.ghgande.j2mod.modbus.io.ModbusRTUTransport.readResponse(ModbusRTUTransport.java:213)
at com.ghgande.j2mod.modbus.io.ModbusSerialTransaction.execute(ModbusSerialTransaction.java:189)
at j2mod.J2mod.main(J2mod.java:73)
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
/ The important instances of the classes mentioned before /
SerialConnection con = null; //the connection
ModbusSerialTransaction trans = null; //the transaction
ReadInputRegistersRequest req = null; //the request
ReadInputRegistersResponse res = null; //the response
/ Variables for storing the parameters /
String portname = null; //the name of the serial port to be used
int unitid = 0; //the unit identifier we will be talking to
int ref = 0; //the reference, where to start reading from
int count = 0; //the count of IR's to read
int repeat = 1; //a loop for repeating the transaction
try {
portname = "COM1";
unitid = 2;
ref = 0;
count = 8;
} catch (Exception ex) {
ex.printStackTrace();
System.exit(1);
}
//2. Set master identifier
//ModbusCoupler.createModbusCoupler(null);
ModbusCoupler.getReference().setUnitID(1);
//3. Setup serial parameters
SerialParameters params = new SerialParameters();
params.setPortName(portname);
params.setBaudRate(1200);
params.setDatabits(8);
params.setParity("None");
params.setStopbits(2);
params.setEncoding("rtu");
params.setEcho(false);
//4. Open the connection
con = new SerialConnection(params);
con.open();
//5. Prepare a request
req = new ReadInputRegistersRequest(ref, count);
req.setUnitID(unitid);
req.setHeadless();
//6. Prepare a transaction
trans = new ModbusSerialTransaction(con);
trans.setRequest(req);
int k = 0;
do {
trans.execute();
res = (ReadInputRegistersResponse) trans.getResponse();
for (int n = 0; n < res.getWordCount(); n++) {
System.out.println("Word " + n + "=" + res.getRegisterValue(n));
}
k++;
} while (k < repeat);
//8. Close the connection
con.close();
}
}
Help me, please.
Last edit: Alikxus 2014-06-02
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
You are both using 1200 baud, or you are both seeing I/O exceptions because the program you wrote is unable to read the response?
If you're having issues with 1200 baud, it is going to take me some doing before I can put together a 1200 baud piece of test hardware.
acp, if you aren't using 1200 baud, please start a different thread. The reason is that 1200 baud is very slow and is probably exposing bugs in the timing code.
As an aside, Modbus will work reliabily at 9600 and 19200 baud for distance up to several hundred meters.
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
I have a problem - Exception in thread "main" com.ghgande.j2mod.modbus.ModbusIOException: I/O exception - failed to read at com.ghgande.j2mod.modbus.io.ModbusRTUTransport.readResponse(ModbusRTUTransport.java:213)
at com.ghgande.j2mod.modbus.io.ModbusSerialTransaction.execute(ModbusSerialTransaction.java:189)
at j2mod.J2mod.main(J2mod.java:73)
when I run this program:
package j2mod;
import com.ghgande.j2mod.modbus.ModbusCoupler;
import com.ghgande.j2mod.modbus.io.ModbusSerialTransaction;
import com.ghgande.j2mod.modbus.msg.ReadInputRegistersRequest;
import com.ghgande.j2mod.modbus.msg.ReadInputRegistersResponse;
import com.ghgande.j2mod.modbus.net.SerialConnection;
import com.ghgande.j2mod.modbus.util.SerialParameters;
public class J2mod {
public static void main(String[] args) throws Exception { // TODO Auto-generated method stub/ The important instances of the classes mentioned before /
SerialConnection con = null; //the connection
ModbusSerialTransaction trans = null; //the transaction
ReadInputRegistersRequest req = null; //the request
ReadInputRegistersResponse res = null; //the response
/ Variables for storing the parameters /
String portname = null; //the name of the serial port to be used
int unitid = 0; //the unit identifier we will be talking to
int ref = 0; //the reference, where to start reading from
int count = 0; //the count of IR's to read
int repeat = 1; //a loop for repeating the transaction
try {
portname = "COM1";
unitid = 2;
ref = 0;
count = 8;
} catch (Exception ex) {
ex.printStackTrace();
System.exit(1);
}
//2. Set master identifier
//ModbusCoupler.createModbusCoupler(null);
ModbusCoupler.getReference().setUnitID(1);
//3. Setup serial parameters
SerialParameters params = new SerialParameters();
params.setPortName(portname);
params.setBaudRate(1200);
params.setDatabits(8);
params.setParity("None");
params.setStopbits(2);
params.setEncoding("rtu");
params.setEcho(false);
//4. Open the connection
con = new SerialConnection(params);
con.open();
//5. Prepare a request
req = new ReadInputRegistersRequest(ref, count);
req.setUnitID(unitid);
req.setHeadless();
//6. Prepare a transaction
trans = new ModbusSerialTransaction(con);
trans.setRequest(req);
int k = 0;
do {
trans.execute();
res = (ReadInputRegistersResponse) trans.getResponse();
for (int n = 0; n < res.getWordCount(); n++) {
System.out.println("Word " + n + "=" + res.getRegisterValue(n));
}
k++;
} while (k < repeat);
//8. Close the connection
con.close();
}
}
Help me, please.
Last edit: Alikxus 2014-06-02
I have a similar issue with Serial connection in an ubuntu.
You are both using 1200 baud, or you are both seeing I/O exceptions because the program you wrote is unable to read the response?
If you're having issues with 1200 baud, it is going to take me some doing before I can put together a 1200 baud piece of test hardware.
acp, if you aren't using 1200 baud, please start a different thread. The reason is that 1200 baud is very slow and is probably exposing bugs in the timing code.
As an aside, Modbus will work reliabily at 9600 and 19200 baud for distance up to several hundred meters.
Julie, we are using 115200 baud. I will move this to a different thread. Thanks.
I am limited to 1200