Question about QModbusRtuSerialMaster

[wangyun]

My QT version is 5.13.1,I use the QModbusRtuSerialMaster class to send the read request ,When I call sendReadRequest function ,the QModbusReply object can not smit finished signal,and the slot can not work.
I use softwore "Modbus Slave" to see the data sent and received. This is my code,help me,please

QModbusDataUnit MbDataUnit(QModbusDataUnit::HoldingRegisters, 0, 2);

pMbReply = pMbSerialClient->sendReadRequest(MbDataUnit, 1);
if (pMbReply != nullptr)
{
	if (pMbReply->isFinished())
	{
		delete pMbReply;
		pMbReply = nullptr;
	}
	else
	{
		connect(pMbReply, &QModbusReply::finished, this, &Qt_ModbusSerial::on_MbSerialClient_readFinished);
	}
}
else
{
	qDebug() << "pMbReply is nullptr";
}