QtModbus 简单示例

Qt Modbus在QtCreator的示例里面有例子，直接搜modbus就可以看到了，简单学一下就能学会了。

QModbusClient *modbusDevice;

1、删除modbus设备对象
if (modbusDevice) modbusDevice->disconnectDevice();
delete modbusDevice;
modbusDevice = nullptr;

2、创建modbus对象
modbusDevice = new QModbusRtuSerialMaster(this);

connect(modbusDevice, &QModbusClient::errorOccurred, [this](QModbusClient::Error){
statusBar()->showMessage(modbusDevice->errorString(), 5000);
});

//检查是否创建modbus master成功
if(!modbusDevice){
ui->btn_connect->setDisabled(true);
statusBar()->showMessage(tr("不能创建Modbus Master。"), 5000);
}else{
//当连接状态出现改变
connect(modbusDevice, &QModbusClient::stateChanged, this, &MainWindow::modbusStateChanged);
}

qDebug() << "创建ModbusDevice成功！";

/**********************modbusStateChanged****************************/
void MainWindow::modbusStateChanged(int state){
if(state == QModbusDevice::UnconnectedState){
ui->btn_connect->setText("连接");
}else{
ui->btn_connect->setText("断开");
}
}
/**************************************************************/
3、配置modbus设备参数
//需要先检查modbus设备是否存在
if (!modbusDevice) return;

if(modbusDevice->state() != QModbusDevice::ConnectedState){
modbusDevice->setConnectionParameter(
QModbusDevice::SerialPortNameParameter, ui->lineEdit_port->text());
modbusDevice->setConnectionParameter(
QModbusDevice::SerialParityParameter, serial_cfig.serial_settings.parity);
modbusDevice->setConnectionParameter(
QModbusDevice::SerialBaudRateParameter, serial_cfig.serial_settings.baud);
modbusDevice->setConnectionParameter(
QModbusDevice::SerialDataBitsParameter, serial_cfig.serial_settings.dataBits);
modbusDevice->setConnectionParameter(
QModbusDevice::SerialStopBitsParameter, serial_cfig.serial_settings.stopBits);

modbusDevice->setTimeout(serial_cfig.serial_settings.responseTime);
modbusDevice->setNumberOfRetries(serial_cfig.serial_settings.numberOfRetries);

//检查modbusDevice是否连接成功
if(!modbusDevice->connectDevice()){
statusBar()->showMessage(tr("连接失败：") + modbusDevice->errorString(), 5000);
qDebug() << "连接失败！";
}else{
ui->btn_connect->setText("断开");
qDebug() << "连接成功！";
}
}else{
modbusDevice->disconnectDevice();
ui->btn_connect->setText("连接");
qDebug() << "断开成功";
}

/**********************************************************************************/

//这里是读写操作

void MainWindow::read_button_clicked()

{

    statusBar()->clearMessage();

    if(!modbusDevice || modbusDevice->state() != QModbusDevice::ConnectedState) {

        statusBar()->showMessage(tr("Modbus Device is not connected!"), 5000);

        return;

    }

    //table

    const auto table = static_cast (ui->comboBox_table->currentData().toInt());

    //读取modbus变量起始地址

    int startAddress = ui->lineEdit_address->text().toInt()-1;

    //读取modbus变量的数量

    int numOfEntries = ui->lineEdit_length->text().toInt();

    //QModbusDataUnit

    QModbusDataUnit dataunit = QModbusDataUnit(table, startAddress, numOfEntries);

    if(auto *reply = modbusDevice->sendReadRequest( dataunit, ui->spinBox_server_address->value())){

        if(!reply->isFinished()) {

            connect(reply, &QModbusReply::finished, this, &MainWindow::read_ready);

        } else {

            delete reply;

        }

    }else{

        statusBar()->showMessage(tr("Read Error:")+modbusDevice->errorString(), 5000);

    }

}

void MainWindow::read_ready()

{

    auto reply = qobject_cast (sender());

    if (!reply) return;

    if (reply->error() == QModbusDevice::NoError) {

        const QModbusDataUnit unit = reply->result();

        ui->textEdit->clear();

        for (uint i = 0; i < unit.valueCount(); i++) {

            const QString entry = tr("Address: %1, Value: %2")

                    .arg(unit.startAddress() + i + 1)

                    .arg(QString::number(unit.value(i)));

            ui->textEdit->append(entry);

        }

    } else if (reply->error() == QModbusDevice::ProtocolError) {

        statusBar()->showMessage(tr("Read response error: %1 (Mobus exception: 0x%2)")

                                 .arg(reply->errorString())

                                 .arg(reply->rawResult().exceptionCode(), -1, 16), 5000);

    } else {

        statusBar()->showMessage(tr("Read response error: %1 (code: 0x%2)")

                                 .arg(reply->errorString())

                                 .arg(reply->error(), -1, 16), 5000);

    }

    reply->deleteLater();

}

void MainWindow::write_button_clicked()

{

    statusBar()->clearMessage();

    if(!modbusDevice || modbusDevice->state() != QModbusDevice::ConnectedState) {

        statusBar()->showMessage(tr("Modbus Device is not connected!"), 5000);

        return;

    }

    //table

    const auto table = static_cast (ui->comboBox_table->currentData().toInt());

    //读取modbus变量起始地址

    int startAddress = ui->lineEdit_address->text().toInt()-1;

    //读取modbus变量的数量

    int numOfEntries = ui->lineEdit_length->text().toInt();

    //QModbusDataUnit

    QModbusDataUnit dataunit = QModbusDataUnit(table, startAddress, numOfEntries);

    for(uint i = 0; i < dataunit.valueCount(); i++){

        dataunit.setValue( i, ui->lineEdit_data->text().toUShort());

    }

    if(auto *reply = modbusDevice->sendWriteRequest(dataunit, ui->spinBox_server_address->value())){

        if(!reply->isFinished()){

            connect(reply, &QModbusReply::finished, this, [this, reply](){

                if(reply->error() == QModbusDevice::ProtocolError){

                    statusBar()->showMessage(tr("Write response error: %1 (Modbus exception:0x%2)")

                                             .arg(reply->errorString()).arg(reply->rawResult().exceptionCode(), -1, 16), 5000);

                }else if(reply->error() != QModbusDevice::NoError){

                    statusBar()->showMessage(tr("Write response error: %1 (code: 0x%2)")

                                             .arg(reply->errorString(), -1, 16), 5000);

                }

                reply->deleteLater();

            });

        }else{

            statusBar()->showMessage(tr("Write error:") + modbusDevice->errorString(), 5000);

        }

    }

}