关于QModbusReply返回QModbusDataUnit不正确问题

[Crazy Frog]

根据Qt自带实例创建了一个Modbus程序，但是读取寄存器单元时可以正常返回数据，读取线圈变量时返回错误数据，谁能帮我看看是怎么回事？

[Crazy Frog]

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include<QMessageBox>

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
create_modbus_client();
}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::create_modbus_client()
{
modbus_client=new QModbusRtuSerialMaster(this);
connect(modbus_client, &QModbusClient::errorOccurred, this {
QMessageBox::warning(this,"QModbus is error",QString("%1").arg(modbus_client->error()));
QMessageBox::warning(this,"QModbus is error",QString("%1").arg(modbus_client->errorString()));
return false;
});
modbus_client->setConnectionParameter(QModbusDevice::SerialPortNameParameter,
tr("COM1"));
modbus_client->setConnectionParameter(QModbusDevice::SerialParityParameter,
QSerialPort::EvenParity);
modbus_client->setConnectionParameter(QModbusDevice::SerialBaudRateParameter,
QSerialPort::Baud9600);
modbus_client->setConnectionParameter(QModbusDevice::SerialDataBitsParameter,
QSerialPort::Data8);
modbus_client->setConnectionParameter(QModbusDevice::SerialStopBitsParameter,
QSerialPort::OneStop);
modbus_client->setTimeout(1000);
modbus_client->setNumberOfRetries(3);
if (!modbus_client->connectDevice()) {
QMessageBox::warning(this,"Error",tr("Connect failed: ") + modbus_client->errorString());
return;
}
else
{

    QMessageBox::about(this,"Congratulation",QString("Create Serial Port Succefully,the name is %1,"
                                                     "the parity is %2,the bandrate is %3,the databits is %4,"
                                                     "the stopbits is %5").arg(modbus_client->connectionParameter(QModbusDevice::SerialPortNameParameter).toString()).
                                                                           arg(modbus_client->connectionParameter(QModbusDevice::SerialParityParameter).toString()).
                                                                           arg(modbus_client->connectionParameter(QModbusDevice::SerialBaudRateParameter).toInt()).
                                                                           arg(modbus_client->connectionParameter(QModbusDevice::SerialDataBitsParameter).toInt()).
                                                                           arg(modbus_client->connectionParameter(QModbusDevice::SerialStopBitsParameter).toInt()));

}

}

QModbusDataUnit MainWindow::return_data_unit()
{

QModbusDataUnit data_unit;
const auto table =
    static_cast<QModbusDataUnit::RegisterType> (ui->RegisterType_comboBox->currentIndex()+1);
data_unit.setRegisterType(table);
data_unit.setStartAddress(ui->StartAddress_spinBox->value());
data_unit.setValueCount(ui->DataNnumber_spinBox->value());
return data_unit;

}

void MainWindow::on_read_pushButton_clicked()
{

read_reply=modbus_client->sendReadRequest(return_data_unit(),ui->ServerAddress_spinBox->value());
/*if(!read_reply->isFinished())
{*/
     connect(read_reply,SIGNAL(finished()),this,SLOT(display_response_value()));
//}

}

void MainWindow::display_response_value()
{

if(read_reply->error()==QModbusDevice::NoError)
{
    const QModbusDataUnit unit = read_reply->result();

    for (uint i = 0; i < unit.valueCount(); i++)
    {
        const QString entry = tr("Address: %1, Value: %2").arg(unit.startAddress())
                                 .arg(QString::number(unit.value(i),
                                      unit.registerType() <= QModbusDataUnit::Coils ? 10 : 16));
        ui->readvalue_listWidget->addItem(entry);
    }
 }

else if(read_reply->error() == QModbusDevice::ProtocolError)
{
    QString entry =tr("Read response error: %1 (QModbusDevice::ProtocolError,Mobus exception: 0x%2)").
                                arg(read_reply->errorString()).
                                arg(read_reply->rawResult().exceptionCode(), -1, 16);
    ui->readvalue_listWidget->addItem(entry);
}
else
{
    QString entry =tr("Read response error: %1 (code: 0x%2)").
            arg(read_reply->errorString()).
            arg(read_reply->error(), -1, 16);
    ui->readvalue_listWidget->addItem(entry);
}
read_reply->deleteLater();

}