Reading/Writing Modbus TCP register in thread.

[Damian7546]

Hi,
To test I write simple thread with Modbus TCP Client. The reading InputRegisters works perfectly., but I have a problem with writing Holding register....
Below is my run() function:

void ClientMachine1::run()
{

    QModbusTcpClient mc;
    QTimer tim_event_timer;
    tim_event_timer.setSingleShot(true);
    QModbusDataUnit du(QModbusDataUnit::InputRegisters,0,10);
    QModbusReply *replyRd;
    QModbusDataUnit wr(QModbusDataUnit::HoldingRegisters,0,6);
    QModbusReply *replyWr;

    //define modbus /write function
    auto wr_redy = [&](){
        if(!replyWr->error()){
            for(int i=0; i<m_holdRegArray.count(); i++)
                   wr.setValue(i, m_holdRegArray[i]);
        }else {
            exit();
            qDebug() << "Error Modbus TCP Client write: " << replyWr->error();
        }
        replyWr->deleteLater();
    };
    //define modbus reply function
    auto rpl_redy =[&](){
        if(!replyRd->error()){
            emit updateDataInReg(id, replyRd->result().value(0)
                                 , replyRd->result().value(1)
                                 , replyRd->result().value(2)
                                 , replyRd->result().value(3)
                                 , replyRd->result().value(4)
                                 , replyRd->result().value(5)
                                 , replyRd->result().value(6)
                                 , replyRd->result().value(7)
                                 , replyRd->result().value(8)
                                 , replyRd->result().value(9));
        tim_event_timer.start(2000);
        }else{
            exit();
            qDebug() << "Error Modbus TCP CLient read: " << replyRd->error();
        }
        replyRd->deleteLater();
    };

    //define event function
    auto eventWr = [&](){
       replyWr=mc.sendWriteRequest(wr,id);
         if(replyWr->isFinished()){
            delete replyWr;
        }else{
            connect(replyWr, &QModbusReply::finished,wr_redy );
        }

    };

    //define timer timeout function
    auto timeoutRd = [&](){
        replyRd=mc.sendReadRequest(du,id);
        if(replyRd->isFinished()){
            delete replyRd;
        }else{
            connect(replyRd, &QModbusReply::finished, rpl_redy);
        }
    };

    //define modbus device state change function
    auto stateChange = [&](QModbusClient::State state){
        if(state==QModbusClient::ConnectedState){
            tim_event_timer.start(1000);
            qDebug() << "ModbusTCPClient is connected";
            emit modbusTCPClientConnectedState(false);
        }else if(state==QModbusClient::UnconnectedState){
            qDebug() << "ModbusTCPClient is disconnected";
            emit modbusTCPClientConnectedState(true);
            exit();
        }else if(state==QModbusClient::ConnectingState){
            qDebug() << "ModbusTCP Client try to connect";
            emit modbusTCPClientConnectedState(true);
        }else{
            qDebug() << "ModbusTCPClient is disconnected";
            emit modbusTCPClientConnectedState(true);
            exit();

        }
    };
    connect(&tim_event_timer, &QTimer::timeout,timeoutRd);
    connect(this, &ClientMachine1::holdRegArrayChanged,eventWr);

    connect(&mc, &QModbusClient::stateChanged,stateChange);

    mc.setConnectionParameter(QModbusDevice::NetworkAddressParameter, "127.0.0.1");
    mc.setConnectionParameter(QModbusDevice::NetworkPortParameter, 5020);
    mc.setTimeout(500);

    if(!mc.connectDevice()){
        exit();
        return;
    }
    exec();
}

When i try write some registers, I have error in line replyWr=mc.sendWriteRequest(wr,id); related with thread:/
QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread QObject: Cannot create children for a parent that is in a different thread. (Parent is QModbusTcpClient(0x4f0f9e0), parent's thread is ClientTicketMach(0x11da0c8), current thread is QThread(0x110a0d0) QObject::startTimer: Timers cannot be started from another thread Error Modbus TCP CLient read: QModbusDevice::TimeoutError QObject::killTimer: Timers cannot be stopped from another thread

Where is problem in my code? How it possible that rpl_redy works , but wr_redy doesnt't works ?
I would be rally gratefull for help to resolve my problem.

[Pl45m4]

@Damian7546 said in Reading/Writing Modbus TCP register in thread.:

QModbusTcpClient

QModbusClient and it's subclasses are asynchronous. Why you want to put it in a thread anyway?

[Damian7546]

To test and knowledge.
I found problem.

This connect:
connect(this, &ClientMachine1::holdRegArrayChanged,eventWr);
run eventWr function in other threat no in run() where is defined.... How can I resolve this ? And run eventWr in my thread by change values in holdRegArray?

[Christian Ehrlicher]

@Damian7546 said in Reading/Writing Modbus TCP register in thread.:

How can I resolve this ?

Use the worker thread approach as described in the documentation to make sure your object you're calling the slots is living in the correct thread instead the main thread as your ClientMachine1 instance in your example. Or even better - don't use thread because they are not needed here and only cause trouble when used wrong (as you did)

[Damian7546]

@Christian-Ehrlicher I have a second problem. When I compile my code on Windows the Modbus TCP Client always connected to server. But when I compile my project on Linux I all the time have QModbusDevice::ConnectingState how it is possible?

[jsulm]

@Damian7546 said in Reading/Writing Modbus TCP register in thread.:

how it is possible?

Different network configuration on your Linux machine for example? Firewall?

[Damian7546]

@Christian-Ehrlicher @jsulm
Thanks for all suggestions and helps. I rewrite my code and now don't use thread to Modbus TCP Client, and everything works ....
Only I have thinking why when I plug out ethernet from my PC the state does not change from Connected to Disconnected ? It change only when I turn off server...

void ClientTicketMach::onModbusStateChanged(int state)
{
    if (state == QModbusDevice::UnconnectedState){
        qDebug() <<"Modbus TCP Client Disconnected";
        tim_reconnect.start(10000);
        tim_reading_inputRegisters.stop();
        emit modbusTCPClientConnectedState(true);
    }
    else if (state == QModbusDevice::ConnectedState){
       qDebug() <<"Modbus TCP Client Connected";
       tim_reading_inputRegisters.start(1000);
       emit modbusTCPClientConnectedState(false);
    }
    else if (state == QModbusDevice::ConnectingState){
        qDebug() << "Modbus TCP Client Connecting";
        emit modbusTCPClientConnectedState(true);
    }
}