Jan 30, 2010 I would like to use Asio to connect to a microcontroller to send and read from, but there are no serial_port samples available.

Detailed Description Provides functions to access serial ports. You can get information about the available serial ports using the helper class, which allows an enumeration of all the serial ports in the system. This is useful to obtain the correct name of the serial port you want to use. You can pass an object of the helper class as an argument to the () or () methods to assign the desired serial device. After setting the port, you can open it in read-only (r/o), write-only (w/o), or read-write (r/w) mode using the () method. Note: The serial port is always opened with exclusive access (that is, no other process or thread can access an already opened serial port). Use the () method to close the port and cancel the I/O operations.

Having successfully opened, tries to determine the current configuration of the port and initializes itself. You can reconfigure the port to the desired setting using the (), (), (), (), and () methods. There are a couple of properties to work with the pinout signals namely:,.

It is also possible to use the () method to query the current pinout signals set. Once you know that the ports are ready to read or write, you can use the () or () methods. Alternatively the () and () convenience methods can also be invoked. If not all the data is read at once, the remaining data will be available for later as new incoming data is appended to the 's internal read buffer.

You can limit the size of the read buffer using (). Provides a set of functions that suspend the calling thread until certain signals are emitted. These functions can be used to implement blocking serial ports: • () blocks calls until new data is available for reading. • () blocks calls until one payload of data has been written to the serial port.

See the following example. Constant Value Description QSerialPort::Baud1200 1200 1200 baud. QSerialPort::Baud2400 2400 2400 baud. QSerialPort::Baud4800 4800 4800 baud. QSerialPort::Baud9600 9600 9600 baud. QSerialPort::Baud0 19200 baud. QSerialPort::Baud0 38400 baud.

QSerialPort::Baud0 57600 baud. QSerialPort::Baud100 115200 baud. QSerialPort::UnknownBaud -1 Unknown baud. This value is obsolete.

It is provided to keep old source code working. We strongly advise against using it in new code. Enum QSerialPort:: DataBits This enum describes the number of data bits used. Constant Value Description QSerialPort::Data5 5 The number of data bits in each character is 5.

It is used for Baudot code. It generally only makes sense with older equipment such as teleprinters. QSerialPort::Data6 6 The number of data bits in each character is 6.

It is rarely used. QSerialPort::Data7 7 The number of data bits in each character is 7. It is used for true ASCII. It generally only makes sense with older equipment such as teleprinters. QSerialPort::Data8 8 The number of data bits in each character is 8. It is used for most kinds of data, as this size matches the size of a byte.

It is almost universally used in newer applications. QSerialPort::UnknownDataBits -1 Unknown number of bits. This value is obsolete. It is provided to keep old source code working. We strongly advise against using it in new code. Enum QSerialPort:: Direction flags QSerialPort:: Directions This enum describes the possible directions of the data transmission.

Note: This enumeration is used for setting the baud rate of the device separately for each direction on some operating systems (for example, POSIX-like). Constant Value Description QSerialPort::NoParity 0 No parity bit it sent. This is the most common parity setting. Error detection is handled by the communication protocol.

QSerialPort::EvenParity 2 The number of 1 bits in each character, including the parity bit, is always even. QSerialPort::OddParity 3 The number of 1 bits in each character, including the parity bit, is always odd. It ensures that at least one state transition occurs in each character. QSerialPort::SpaceParity 4 Space parity. The parity bit is sent in the space signal condition. It does not provide error detection information.

QSerialPort::MarkParity 5 Mark parity. The parity bit is always set to the mark signal condition (logical 1). It does not provide error detection information. QSerialPort::UnknownParity -1 Unknown parity. This value is obsolete. It is provided to keep old source code working. We strongly advise against using it in new code.

Enum QSerialPort:: PinoutSignal flags QSerialPort:: PinoutSignals This enum describes the possible RS-232 pinout signals. Constant Value Description QSerialPort::NoSignal 0x00 No line active QSerialPort::TransmittedDataSignal 0x01 TxD (Transmitted Data).

This value is obsolete. It is provided to keep old source code working. We strongly advise against using it in new code. QSerialPort::ReceivedDataSignal 0x02 RxD (Received Data).

This value is obsolete. It is provided to keep old source code working. We strongly advise against using it in new code. QSerialPort::DataTerminalReadySignal 0x04 DTR (Data Terminal Ready). QSerialPort::DataCarrierDetectSignal 0x08 DCD (Data Carrier Detect). QSerialPort::DataSetReadySignal 0x10 DSR (Data Set Ready).

QSerialPort::RingIndicatorSignal 0x20 RNG (Ring Indicator). QSerialPort::RequestToSendSignal 0x40 RTS (Request To Send). QSerialPort::ClearToSendSignal 0x80 CTS (Clear To Send). QSerialPort::SecondaryTransmittedDataSignal 0x100 STD (Secondary Transmitted Data). QSerialPort::SecondaryReceivedDataSignal 0x200 SRD (Secondary Received Data). The PinoutSignals type is a typedef for. It stores an OR combination of PinoutSignal values.

See also (),, and. Enum QSerialPort:: SerialPortError This enum describes the errors that may be contained by the property. Constant Value Description QSerialPort::NoError 0 No error occurred. QSerialPort::DeviceNotFoundError 1 An error occurred while attempting to open an non-existing device. QSerialPort::PermissionError 2 An error occurred while attempting to open an already opened device by another process or a user not having enough permission and credentials to open.

QSerialPort::OpenError 3 An error occurred while attempting to open an already opened device in this object. QSerialPort::NotOpenError 13 This error occurs when an operation is executed that can only be successfully performed if the device is open. This value was introduced in 5.2. QSerialPort::ParityError 4 Parity error detected by the hardware while reading data. This value is obsolete.

We strongly advise against using it in new code. QSerialPort::FramingError 5 Framing error detected by the hardware while reading data. This value is obsolete. We strongly advise against using it in new code. QSerialPort::BreakConditionError 6 Break condition detected by the hardware on the input line. This value is obsolete.

We strongly advise against using it in new code. QSerialPort::WriteError 7 An I/O error occurred while writing the data. QSerialPort::ReadError 8 An I/O error occurred while reading the data. QSerialPort::ResourceError 9 An I/O error occurred when a resource becomes unavailable, e.g. When the device is unexpectedly removed from the system. QSerialPort::UnsupportedOperationError 10 The requested device operation is not supported or prohibited by the running operating system.

QSerialPort::TimeoutError 12 A timeout error occurred. This value was introduced in 5.2. QSerialPort::UnknownError 11 An unidentified error occurred. Enum QSerialPort:: StopBits This enum describes the number of stop bits used. Property Documentation baudRate: 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 property. To set the baud rate, use the enumeration or any positive qint32 value.

Note: If the setting is set before opening the port, the actual serial port setting is done automatically in the () method right after that the opening of the port succeeds. Warning: Setting the flag is supported on all platforms. Windows supports only this mode. Warning: Returns equal baud rate in any direction on Windows. The default value is Baud9600, i.e. 9600 bits per second. Access functions.

Brookstone Slcd V3 0 Manualidades. Void (qint32 baudRate, QSerialPort::Directions directions) breakEnabled: bool 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.

Note: The serial port has to be open before trying to set or get this property; otherwise returns false and sets the error code. This is a bit unusual as opposed to the regular Qt property settings of a class. However, this is a special use case since the property is set through the interaction with the kernel and hardware. Hence, the two scenarios cannot be completely compared to each other. This property was introduced in Qt 5.5. Access functions.

Void breakEnabledChanged(bool set) dataBits: 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 property. Note: If the setting is set before opening the port, the actual serial port setting is done automatically in the () method right after that the opening of the port succeeds.

The default value is Data8, i.e. Access functions. SerialPortError error() const void clearError() flowControl: 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 property. Note: If the setting is set before opening the port, the actual serial port setting is done automatically in the () method right after that the opening of the port succeeds. The default value is, i.e. No flow control.

Access functions. Void (QSerialPort::FlowControl flow) parity: 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 property. Note: If the setting is set before opening the port, the actual serial port setting is done automatically in the () method right after that the opening of the port succeeds. The default value is, i.e. Access functions. Void (QSerialPort::Parity parity) requestToSend: bool 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. Note: The serial port has to be open before trying to set or get this property; otherwise false is returned and the error code is set to. Note: An attempt to control the RTS signal in the mode will fail with error code set to, because the signal is automatically controlled by the driver. Access functions.

Void (bool set) See also (). StopBits: 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 property. Note: If the setting is set before opening the port, the actual serial port setting is done automatically in the () method right after that the opening of the port succeeds. The default value is, i.e. Access functions.

Member Function Documentation QSerialPort:: QSerialPort( * parent = nullptr) Constructs a new serial port object with the given parent. QSerialPort:: QSerialPort(const & name, * parent = nullptr) 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 () method. QSerialPort:: QSerialPort(const & serialPortInfo, * parent = nullptr) Constructs a new serial port object with the given parent to represent the serial port with the specified helper class serialPortInfo. [virtual] QSerialPort:: ~QSerialPort() Closes the serial port, if necessary, and then destroys object.

[virtual] bool QSerialPort:: atEnd() const Reimplemented from (). 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. Platform Brief Description Windows Removes the prefix '. ' or '//./' from the system location and returns the remainder of the string. Unix, BSD Removes the prefix '/dev/' from the system location and returns the remainder of the string. See also (), (), and ().

QSerialPort:: readBufferSize() const Returns the size of the internal read buffer. This limits the amount of data that the client can receive before calling the () or () methods. A read buffer size of 0 (the default) means that the buffer has no size limit, ensuring that no data is lost. See also () and ().

[virtual protected] QSerialPort:: readData( char * data, maxSize) Reimplemented from (). [virtual protected] QSerialPort:: readLineData( char * data, maxSize) Reimplemented from ().

[signal] void QSerialPort:: requestToSendChanged( bool set) 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. Note: Notifier signal for property. Bool QSerialPort:: sendBreak( int duration = 0) This function is deprecated.

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. Note: The serial port has to be open before trying to send a break duration; otherwise returns false and sets the error code. Void QSerialPort:: setPort(const & serialPortInfo) Sets the port stored in the serial port info instance serialPortInfo.

See also () and. Void QSerialPort:: setPortName(const & name) 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. See also () and.

Void QSerialPort:: setReadBufferSize( size) Sets the size of 's internal read buffer to be size bytes. If the buffer size is limited to a certain size, 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. See also () and (). [signal] void QSerialPort:: stopBitsChanged( stopBits) 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. Note: Notifier signal for property. [virtual] bool QSerialPort:: waitForBytesWritten( int msecs = 30000) Reimplemented from (). This function blocks until at least one byte has been written to the serial port and the 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 () signal is emitted; otherwise it returns false (if an error occurred or the operation timed out). [virtual] bool QSerialPort:: waitForReadyRead( int msecs = 30000) Reimplemented from (). This function blocks until new data is available for reading and the 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 () signal is emitted and there is new data available for reading; otherwise it returns false (if an error occurred or the operation timed out). [virtual protected] QSerialPort:: writeData(const char * data, maxSize) Reimplemented from (). © 2017 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the as published by the Free Software Foundation.

Qt and respective logos are trademarks of The Qt Company Ltd. In Finland and/or other countries worldwide.

All other trademarks are property of their respective owners.

A 24lb Pizza 15-Sep-15 12:01 15-Sep-15 12:01 Hello, I know this is an old article, but I am hoping I will be able to get some help with this matter as it doesn't necessarily relate directly to the serial communication. I am fairly new to c++ so this is perhaps actually a really silly problem. I am creating a windows console application that asks the user for the desired baud rate, parity, etc. Then it will open the serial port and begin communicating. My problem is that I want get all the parameters and verify them one at a time, then use CSerial::Setup(). Now all my user inputs are of the format std::string and I want to convert them to formats that are useful for this serial class. My thought was that I could somehow create variables of the same type.

Example: EBaudrate ebaudrate = CSerial::EBaud19200 or something along those lines where the type is EBaudrate. If anyone could help me that would be great, thank you for your time, Mitch -- Extra information -- Compiler: Visual Studio 2010 Express Library in question: CSerial.

Member 10290644 22-Jul-15 19:36 22-Jul-15 19:36 Hi, The MFC flavor compiles and works nicely with MSVC++ 6.0. However i recently tried to recompile it using MSVC++ in VS2015, and i get the following errors: C2440 'type cast': cannot convert from 'void(_thiscall CWnd::*) (WPARAM,LPARAM)' invalid type conversion I did a bit of digging and it seems MSVC++ 2015 won't allow parameters to be passed in the message map whereas version 6.0 allowed it. But looks like the MFC implementation of this serial class MUST pass a parameter particularly if multiple serial ports are used. What should i do? Member 11246861 6-Dec-14 8:23 6-Dec-14 8:23 I've downloaded your demo and compiled it in my VC++ 2013 Ultimate. I had to add only #define WINVER 0x0502 in your StdAfx.h and to add the linker option FORCE:MULTIPLE.

All projects are built. I'm testing HelloWorld.cpp with my lent microcontroller plugged to the USB of my laptop. HelloWorld runs without errors and Rx LED of the microcontroller goes ON for a moment. I think it's a success. I'll write more, perhaps tomorrow.

I don't need any replies. Thanks again. Michael Stammberger 21-Jan-14 2:47 21-Jan-14 2:47 If you have problems to use the CSerial class with a virtual com port (VCOM): Did you already examine the behaviour of the VCOM port concerning the settings of the DTR (and RTS) signals? As stated in section 'Virtual COM Ports.'

: 'Receiving spurious events is another problem, which is quite common when using virtual COM ports.' I had to communicate with a device using the (w/o handshaking) and was very confused about receiving the event EEventSend instead of the expected EEventRecv - even if EEventSend was masked out. The expected EEventRecv never arrived! On the other hand the communication worked well with other programs which don't use CSerial, but also using overlapped-io, nonblocking communication. By analysing the communication with Sysinternals tool and comparing the differencies between the not working CSerial based program and the working program it came to light: The virtual COM port requires the DTR signal to be set to high - even if there is no handshaking used at all! After changing the DTR to high the communication was working.

No more spurious events anymore. Problem solved!

(I don't understand at all, why a wrong DTR signal leads to spurious events, but anyways.) There are different appraoches to change the DTR settings. Please look into the following thread for more information: As far as I know there is no standard available how the DTR line has to be set by default. But I found some hints saying 'conventionally the DTR is set to high if the port is opened'. So I changed CSerial to do it this way by default. I hope this information might be helpful for somebody. Best regards Michael. Member 10335754 14-Oct-13 10:17 14-Oct-13 10:17 My reading of this sample code suggests that when using Overlapped IO the calls to ReadFile and WriteFile don't include the same OVERLAPPED structure as is used for the call to WaitEvents.

In fact all 3 calls use distinct structures created per call. However, MS documentation asserts 'After opening the file object for asynchronous I/O, an OVERLAPPED structure must be properly created, initialized, and passed into each call to functions such as ReadFile and WriteFile. I don't understand why the two articles seem to differ. What am I trying to do. I want to write a application that uses a single thread to read from and write to an external device via a COM port (on NT4.0).

The messages read and written are not co-ordinated. By that I mean the application may write a message to the COM port 'at the same time' as the external device sends a message to be read. I propose that a separate (2nd) thread in my application will raise an event to inidicate to the 1st (serial) thread when a message is available to send to the device. Summary of my Question 1. Can I use the Overalapped.cpp example to wait for multiple objects using one event for overlapped IO (as in the example) and another to trigger a message write?

Should both calls to Serial::Read() and Serial::Write() be made without passing in an OVERLAPPED structure?