QSerialPort exchange problems with hardware flow control

Now I write a data exchange program in QT Creator 5.12 through, say, a specific data network. The modems of this network operate over UART RS-232, only in hardware flow control mode.

Key part of the problem.

At delivery of the problems given to the port no, I can install or dump signals of DTR and RTS QSerialPort:: dataTerminalReady(bool), and QSerialPort:: requestToSend(bool) and to check existence of replies of CTS and DSR by means of QSerialPort::pinoutSignals(). And, of course, after that, transfer the data successfully.

Problems at reception of data from the device: I assume that the reason in absence in the class QSerialPort of the methods QSerialPort::setClearToSend(bool) and QSerialPort::setDataSetReady(bool) as I cannot respond CTS to the request from the equipment of the channel of data of RTS and to respond DTR for request DSR to accept data at hardware control of a stream though I, of course, can see these inquiries by means of QSerialPort::pinoutSignals(). So just transferring data from the modem to my program doesn't start. Signals were observed using an oscilloscope.

Of course, theoretically, it is possible to make a special cable where the RTS signals on the CTS and DTR on the DSR inside each connector will be looped, but the equipment with cables has long been at the receiver and it is not possible to rewrite the port controller code in the "modem" to unmanaged data flow transmission.