QSerialPort Class

See also QSerialPortInfo

This enum describes the baud rate which the communication device operates with.

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This enum describes the number of data bits used.

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flags QSerialPort::Directions

This enum describes the possible directions of the data transmission.

The Directions type is a typedef for QFlags<Direction>. It stores an OR combination of Direction values.

This enum describes the flow control used.

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This enum describes the parity scheme used.

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flags QSerialPort::PinoutSignals

This enum describes the possible RS-232 pinout signals.

The PinoutSignals type is a typedef for QFlags<PinoutSignal>. It stores an OR combination of PinoutSignal values.

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This enum describes the errors that may be contained by the QSerialPort::error property.

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This enum describes the number of stop bits used.

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This property holds the data baud rate for the desired direction

If the setting is successful or set before opening the port, returns true; otherwise returns false and sets an error code which can be obtained by accessing the value of the QSerialPort::error property. To set the baud rate, use the enumeration QSerialPort::BaudRate or any positive qint32 value.

The default value is Baud9600, i.e. 9600 bits per second.

Access functions:

• baudRate( directions = AllDirections) const

• bool setBaudRate( baudRate, directions = AllDirections)

Notifier signal:

• void baudRateChanged( baudRate, directions)

This property holds the state of the transmission line in break

Returns true on success, false otherwise. If the flag is true then the transmission line is in break state; otherwise is in non-break state.

This property was introduced in Qt 5.5.

Access functions:

• bool isBreakEnabled() const

• bool setBreakEnabled(bool set = true)

Notifier signal:

• void breakEnabledChanged(bool set)

This property holds the data bits in a frame

If the setting is successful or set before opening the port, returns true; otherwise returns false and sets an error code which can be obtained by accessing the value of the QSerialPort::error property.

The default value is Data8, i.e. 8 data bits.

Access functions:

• dataBits() const

• bool setDataBits( dataBits)

Notifier signal:

• void dataBitsChanged( dataBits)

This property holds the state (high or low) of the line signal DTR

Returns true on success, false otherwise. If the flag is true then the DTR signal is set to high; otherwise low.

Access functions:

• bool isDataTerminalReady()

• bool setDataTerminalReady(bool set)

Notifier signal:

• void dataTerminalReadyChanged(bool set)

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This property holds the error status of the serial port

The I/O device status returns an error code. For example, if open() returns false, or a read/write operation returns -1, this property can be used to figure out the reason why the operation failed.

The error code is set to the default QSerialPort::NoError after a call to clearError()

Access functions:

• error() const

• void clearError()

This property holds the desired flow control mode

If the setting is successful or set before opening the port, returns true; otherwise returns false and sets an error code which can be obtained by accessing the value of the QSerialPort::error property.

The default value is NoFlowControl, i.e. no flow control.

Access functions:

• flowControl() const

• bool setFlowControl( flowControl)

Notifier signal:

• void flowControlChanged( flow)

This property holds the parity checking mode

If the setting is successful or set before opening the port, returns true; otherwise returns false and sets an error code which can be obtained by accessing the value of the QSerialPort::error property.

The default value is NoParity, i.e. no parity.

Access functions:

• parity() const

• bool setParity( parity)

Notifier signal:

• void parityChanged( parity)

This property holds the state (high or low) of the line signal RTS

Returns true on success, false otherwise. If the flag is true then the RTS signal is set to high; otherwise low.

Access functions:

• bool isRequestToSend()

• bool setRequestToSend(bool set)

Notifier signal:

• void requestToSendChanged(bool set)

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This property holds the number of stop bits in a frame

If the setting is successful or set before opening the port, returns true; otherwise returns false and sets an error code which can be obtained by accessing the value of the QSerialPort::error property.

The default value is OneStop, i.e. 1 stop bit.

Access functions:

• stopBits() const

• bool setStopBits( stopBits)

Notifier signal:

• void stopBitsChanged( stopBits)

Constructs a new serial port object with the given parent.

Constructs a new serial port object with the given parent to represent the serial port with the specified name.

The name should have a specific format; see the setPort() method.

Constructs a new serial port object with the given parent to represent the serial port with the specified helper class serialPortInfo.

Closes the serial port, if necessary, and then destroys object.

Reimplements: QIODevice::atEnd() const.

Returns true if no more data is currently available for reading; otherwise returns false.

This function is most commonly used when reading data from the serial port in a loop. For example:

// This slot is connected to QSerialPort::readyRead()
void QSerialPortClass::readyReadSlot()
{
    while (!port.atEnd()) {
        QByteArray data = port.read(100);
        ....
    }
}

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This signal is emitted after the baud rate has been changed. The new baud rate is passed as baudRate and directions as directions.

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Reimplements: QIODevice::bytesAvailable() const.

Returns the number of incoming bytes that are waiting to be read.

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Reimplements: QIODevice::bytesToWrite() const.

Returns the number of bytes that are waiting to be written. The bytes are written when control goes back to the event loop or when flush() is called.

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Reimplements: QIODevice::canReadLine() const.

Returns true if a line of data can be read from the serial port; otherwise returns false.

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Discards all characters from the output or input buffer, depending on given directions directions. This includes clearing the internal class buffers and the UART (driver) buffers. Also terminate pending read or write operations. If successful, returns true; otherwise returns false.

Reimplements: QIODevice::close().

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This signal is emitted after the data bits in a frame has been changed. The new data bits in a frame is passed as dataBits.

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This signal is emitted after the state (high or low) of the line signal DTR has been changed. The new the state (high or low) of the line signal DTR is passed as set.

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This signal is emitted when an error occurs in the serial port. The specified error describes the type of error that occurred.

This function was introduced in Qt 5.8.

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This signal is emitted after the flow control mode has been changed. The new flow control mode is passed as flow.

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This function writes as much as possible from the internal write buffer to the underlying serial port without blocking. If any data was written, this function returns true; otherwise returns false.

Call this function for sending the buffered data immediately to the serial port. The number of bytes successfully written depends on the operating system. In most cases, this function does not need to be called, because the QSerialPort class will start sending data automatically once control is returned to the event loop. In the absence of an event loop, call waitForBytesWritten() instead.

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If the platform is supported and the serial port is open, returns the native serial port handle; otherwise returns -1.

This function was introduced in Qt 5.2.

Reimplements: QIODevice::isSequential() const.

Always returns true. The serial port is a sequential device.

Reimplements: QIODevice::open(QIODevice::OpenMode mode).

Opens the serial port using OpenMode mode, and then returns true if successful; otherwise returns false and sets an error code which can be obtained by calling the error() method.

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This signal is emitted after the parity checking mode has been changed. The new parity checking mode is passed as parity.

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Returns the state of the line signals in a bitmap format.

From this result, it is possible to allocate the state of the desired signal by applying a mask "AND", where the mask is the desired enumeration value from QSerialPort::PinoutSignals.

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Returns the name set by setPort() or passed to the QSerialPort constructor. This name is short, i.e. it is extracted and converted from the internal variable system location of the device. The conversion algorithm is platform specific:

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Returns the size of the internal read buffer. This limits the amount of data that the client can receive before calling the read() or readAll() methods.

A read buffer size of 0 (the default) means that the buffer has no size limit, ensuring that no data is lost.

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Reimplements: QIODevice::readData(char *data, qint64 maxSize).

Reimplements: QIODevice::readLineData(char *data, qint64 maxSize).

This signal is emitted after the state (high or low) of the line signal RTS has been changed. The new the state (high or low) of the line signal RTS is passed as set.

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Sends a continuous stream of zero bits during a specified period of time duration in msec if the terminal is using asynchronous serial data. If successful, returns true; otherwise returns false.

If the duration is zero then zero bits are transmitted by at least 0.25 seconds, but no more than 0.5 seconds.

If the duration is non zero then zero bits are transmitted within a certain period of time depending on the implementation.

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Sets the port stored in the serial port info instance serialPortInfo.

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Sets the name of the serial port.

The name of the serial port can be passed as either a short name or the long system location if necessary.

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Sets the size of QSerialPort's internal read buffer to be size bytes.

If the buffer size is limited to a certain size, QSerialPort will not buffer more than this size of data. The special case of a buffer size of 0 means that the read buffer is unlimited and all incoming data is buffered. This is the default.

This option is useful if the data is only read at certain points in time (for instance in a real-time streaming application) or if the serial port should be protected against receiving too much data, which may eventually cause the application to run out of memory.

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This signal is emitted after the number of stop bits in a frame has been changed. The new number of stop bits in a frame is passed as stopBits.

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Reimplements: QIODevice::waitForBytesWritten(int msecs).

This function blocks until at least one byte has been written to the serial port and the bytesWritten() signal has been emitted. The function will timeout after msecs milliseconds; the default timeout is 30000 milliseconds. If msecs is -1, this function will not time out.

The function returns true if the bytesWritten() signal is emitted; otherwise it returns false (if an error occurred or the operation timed out).

Reimplements: QIODevice::waitForReadyRead(int msecs).

This function blocks until new data is available for reading and the readyRead() signal has been emitted. The function will timeout after msecs milliseconds; the default timeout is 30000 milliseconds. If msecs is -1, this function will not time out.

The function returns true if the readyRead() signal is emitted and there is new data available for reading; otherwise it returns false (if an error occurred or the operation timed out).

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Reimplements: QIODevice::writeData(const char *data, qint64 maxSize).

enum QSerialPort::DataErrorPolicy▲

dataErrorPolicy : DataErrorPolicy▲

settingsRestoredOnClose : bool▲

void QSerialPort::dataErrorPolicyChanged(QSerialPort::DataErrorPolicy policy)▲

void QSerialPort::error(QSerialPort::SerialPortError error)▲

void QSerialPort::settingsRestoredOnCloseChanged(bool restore)▲