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win32 serial port example

This is the fourth in a series of articles concerning Windows SDK development that I have written over the years. The first three are:. Several years ago, I wanted to have a simple to use, message based, serial port control that I could employ in my Win32 C projects.

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I started experimenting with the idea and playing around with the serial port in my spare time, but as so often happens, the project ended up on the shelf when I got busy again. Recently, I came across that project and, with a better understanding of how serial port communications work on Windows, decided to finish it.

Since I haven't encountered a serial port wrapper that takes this approach anywhere, I decided to publish it on The Code Project. The Windows SDK provides methods for configuring the serial port. Other methods are available for monitoring the port and raising events, as well as file stream methods for reading and writing data.

Take it all together, and serial port communication can become a somewhat daunting exercise. This control packs most of that functionality into a single Windows class that can be included in a Win32 project and accessed using standard Windows messaging and notifications.

This serial port control is a message based, custom control, and as such must be initialized before use. One way to handle this is to call the initializer in the WinMain method of the application just after the call to InitCommonControlsEx.

To make things simple though, I combined this step in the control's pseudo constructor. It is called only once, the first time a new serial port control is instantiated.

These examples show some of the ways that the control can be simply implemented in a Win32 project. To demonstrate the class in a useful context, I put together a demo that makes use of two modems connected to two land lines.

I happened to have the lines and hardware available to play with, but even without them, the demo code should give a fairly complete idea of how to use the class. Configure the control to do what you want using Windows messages. To make this easy and as a way of documenting the messages, I created macros for each message. If you prefer to call SendMessage or PostMessage explicitly, please refer to the macro defs in the header for usage.

In order to have a serial port control with notifications, I employed asynchronous overlapped IO along with WaitCommEvent in a working thread that listens to the serial port and posts any activity to the main thread.

I created methods to launch, and if necessary, terminate this thread. Here is the code that runs in the working thread:. The upside of this is that you can respond to notifications and update the user interface without the threat of cross threading.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

I am working with a peripheral device that needs to be communicated through serial. I can send it commands using HyperTerminal, but now I need to write programs that will let me do it without HyperTerminal. Microsoft provides an article with sample code describing how to do this under Win Boost:asio may be able to help as a serial device was added recently.

Fair warning though; the serial port documentation is lightpresumably since it's quite new it was added in asio 1. It'll be easier to read and maintain it's a higher level API and it'll be cross platform except where you need to specify the OS-specific device name. The Boost - Users and asio.

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If using. NET 2. Ports and this article should be helpful. If direct Win32, then Adam's answer is best. I believe you will find plenty of sample code for C as well if you find VC6 too ancient.

Learn more. Asked 11 years, 5 months ago. Active 7 years, 6 months ago. Viewed 14k times.

Win32 SDK Serial Comm Made Easy

Mike Mike. Active Oldest Votes. Adam Rosenfield Adam Rosenfield k 89 89 gold badges silver badges bronze badges. Do you think the linked article is still relevant?

Win32_SerialPort class

Is there a better way these days? Andru Luvisi Andru Luvisi MattyT MattyT 5, 2 2 gold badges 17 17 silver badges 16 16 bronze badges. Boost does a horrible job of Win32 error checking in multi-threaded programs. It outright ignores return values for WaitForSingleObject.

Use at your own peril, if you don't mind trying to track down their bugs in a threaded program. Tim Tim Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.Email Contact Us. In this tutorial we will learn How to communicate with an external device like a microcontroller board or modem using the Serial port of a windows PC Windows XP,7. The Board can also be used as an FT development board.

All the C sourefiles used in this tutorial can be downloaded from our GitHub Page. Please note that the sourcecodes on the website show only the relevant sections to highlight the process of programming the serial port. Please use the complete sourcecodes from our github repo when building your own program. Visual Studio Express Edition for Desktop can be freely downloaded its a large download from Microsoft's website.

After you have installed the MinGW, package make sure to add gcc to system path so that you can call it from anywhere.

Serial port programming using Win32 API (Windows)

If you double click on COM24,you can see the details of the corresponding port. CreateFile is a Win 32 function which is used to create or open a file, stream or an IO device like serial port. On success CreateFile will return a handle which is then used to refer the connection in all subsequent operations. After opening a serial port using the CreateFile function you should close it with CloseHandle function, otherwise port will become unavailable to other programs. Now let's write a small program to open and close a serial port on Windows.

Now compile and run the program by pressing F5 in Visual Studio or by running the following command for gcc MingW. Now let me explain the codewindows. In Windows everything is controlled by using handles. Next we open a connection to serial port using CreateFile function. CreateFile function takes 7 arguments. Mode of access, here Read and Write 3. Sharing options, Serial ports can't be shared so 0 4. Overlapped IO is used for multithreaded programs where several threads can interact with the port simultaneously.

NULL for Serial port, used for file operations. If the function succeeds in opening the serial port, it returns a valid handle to hcomm which is then used for error checking.

After that the connection to the port is closed using. CloseHandle hComm. You can access the serial port like this. To Configure the DCB structure we use two functions, GetCommState function which retrieves the current control settings of the serial port and SetCommState function which configures the serial port with the new values in DCB structure provided by us. First you declare a new structure of type DCB and initializes it.

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Setting Timeouts Timeouts helps to prevent your program from waiting endlessly till data arrives. It helps the read or write calls to return after a set time period has elapsed. All values are in milliseconds. ReadIntervalTimeout Specifies the maximum time interval between arrival of two bytes. If the arrival time exceeds these limits the ReadFile function returns. ReadTotalTimeoutConstant is used to calculate the total time-out period for read operations.The purpose of this article is to describe how to interface to serial port on Win This article explains the use of serial port on Win32 platform by file operation technique.

The programmer can use kernel Therefore it's possible to open a serial port by using Windows file-creating function. This article explains not only about serial port communication but also how to implement multi-tasking that can apply with our project "serial port" application. The reason why the software serial communication will be implemented with multi-tasking method is that the serial communication application has to handle work with more than one task at the same time.

For example data-reading task, data-sending task, GUI task etc. The first step in opening a serial port is initiation or setting a serial port's configuration.

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The purpose of this is to create the serial port agent. All throughout the article we are going to use a file handle as serial port agent. The serial port's handle is a handle that can be used to access the object of serial port. The function that is used to create the serial port handle is the CreateFile function. The following code shows the function that is used to create a handle:. It is used to specify port name that wants to create a serial port handle. The restoration of serial port configuration is getting current configuration at control device.

The configuration of serial port includes parameters that are used for setting a serial communications device. The GetCommState function is used to get the current device-control and then fills to a device-control block a DBC structure with the current control settings for a specified communications device.

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The following code shows the function that is used to get the current control device:. When you already have serial port configuration in the DBC format, you have to modify parameters a bit. Following code shows the parameters modified:. Note: Recommend that programmers use default value for typical communication. As shown in figure 3, Watch Dialog Box shows the default values that are used for typical communication.

The next step is the storage of new configuration that is modified already into device control. The SetCommState function configures a communications device according to the specifications in a device-control block a DBC structure.

The function reinitializes all hardware and control settings, but it does not empty output or input queues. Following code shows storage of a new configuration:. The code below shows setting time-out of communication:. Specifies the maximum time, in milliseconds, allowed to elapse between the arrival of two characters on the communications line. During a ReadFile operation, the time period begins when the first character is received.

If the interval between the arrival of any two characters exceeds this amount, the ReadFile operation is completed and any buffered data is returned. A value of zero indicates that interval time-outs are not used.

Specifies the multiplier, in milliseconds, used to calculate the total time-out period for read operations. For each read operation, this value is multiplied by the requested number of bytes to be read.

Specifies the constant, in milliseconds, used to calculate the total time-out period for read operations. For each read operation, this value is added to the product of the ReadTotalTimeoutMultiplier member and the requested number of bytes. A value of zero for both the ReadTotalTimeoutMultiplier and ReadTotalTimeoutConstant members indicates that total time-outs are not used for read operations. Specifies the multiplier, in milliseconds, used to calculate the total time-out period for write operations.

For each write operation, this value is multiplied by the number of bytes to be written. Specifies the constant, in milliseconds, used to calculate the total time-out period for write operations.This should solve a problem occuring with some devices hyperterminal problem.

If you experience any problem using this software, please be sure that you have the latest version. Check our web site www. Otherwise report any bug to the address above or check the FAQ.

Here it is. Finally, I think I've reached the final step in serial communication programmation on Win This software has already been downloaded by several thousands of programmers all around the world!

This new version V2. I can handle either 1-byte exchange like a UART or arrays of byte. And more important of all, this new version handles also modem specific signals like CD and RI. CD allows you to know if the modem is connected to the other modem or if you are in command mode. I've removed the "non event-driven" version since I believe it is not so usefull. Anyway, you can still download the V1.

win32 serial port example

The version 2 can be downloaded here serial2. I hope that this version will be the ultimate library for the serial port. I hope to receive your comments about it.

Since the version 1.

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If you like this software, please let me know, 'cause I like to know what people think of my work. Please find hereafter the updated version of the documentation. Bye Thierry Schneider. Every programmer knows that accessing the hardware ports of a computer is getting more and more complicated. The software presented here intends to ease the development of applications using the serial port COM on computer running Windows bits operating systems.

Allen Denver, from the Microsoft Windows Developer Support wrote one of the only technical article describing in details how to use the serial port under WinSometimes we require to communicate with an external device like a printer, microcontroller board or any serial device using the serial port of a windows machine.

We can use any one of them for serial communication but sometimes we require to create our own custom serial application for communication. In windows, it is easy to create the custom serial application using the win32 API. In this blog post, we will learn serial port programming using the Win32 API.

You can also see the below articles that how to change the properties of com-port like baud rate, parity using the Windows API. It also possible that com id could be virtual for example static virtual com port.

Here I have used Visual Studio In Windows using the CreateFilewe can open the serial port. On success CreateFile returns a handle that can be used to access the file or device depending on the flags and attributes specified.

You should remember that after opening the com port using the CreateFileyou have to close it by calling the CloseHandle otherwise it will be unavailable to other applications. Let see an example code where I am talking with a Mega Arduino device. I have written a small code for mega in which it receives serial data. See the below video where I have downloaded the Arduino code in the Arduino board and communicating with this board using the console application.

Skip to content. About Amlendra I am an embedded c software engineer and a corporate trainer, currently, I am working as senior software engineer in a largest Software consulting company. You might also like. C LanguageOperating System. C Language. C LanguageFile handling. Leave a Reply Cancel reply.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time.

Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I have found a couple unanswered questions on SO that are similar I am using Bluetooth adapters RN to make a serial connection. The adapters SPP create two virtual com ports This is common to all adapters we have tested.

Windows labels them as Incoming and Outgoing, but the Incoming is the only one that actually carries serial data. That leaves me with 'extra' virtual serial ports. I populate a dropdown with the available Com ports so the user can select the port to connect to from the list. The problem is that after this runs my Com Port locks up and I cannnot make any connection until I remove my bluetooth adapter and restart the remote device RN Any thoughts?

For certain resource types typically physical portsusing "synchronous" or even "semi-synchronous" WQL queries can interrupt or even cause denial of service on the services managing those resources. If nothing occurs within the timeout, the query returns an empty result-set, and you restart the loop send another query.

PowerEvents for Windows Powershell is a good example of tooling in this area. Learn more.

win32 serial port example

Asked 6 years, 2 months ago. Active 4 years, 5 months ago.

win32 serial port example

Viewed 4k times. Prior to that, I am filtering that list to remove the 'fake' com ports. GetPropertyValue "Name". Add property. Count ; ports. Matthew Hilgenfeld Matthew Hilgenfeld 3 3 silver badges 15 15 bronze badges. Probably because this is a synchronous query.

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