GENERIC_READ | GENERIC_WRITE, //Read/Write
Open a text editor like notepad and type the below code and save it as “ serial.c”.If you are using IDE like VS Express, use the one integrated with it.
Now let's write a small program to open and close a serial port on Windows. On success CreateFileA() will return a handle which is then used to refer the connection in all subsequent operations.Īfter opening a serial port using the CreateFileA() function you should close it with CloseHandle() function, otherwise port will become unavailable to other programs. We use the CreateFileA() function to open a serial port.ĬreateFile() is a Win 32 function which is used to create or open a file, stream or an IO device like serial port. The codes/executables are able to open the connection to the serial port under both Administrator Account and Standard User Account in Windows 10. If you double click on COM24,you can see the details of the corresponding port. I am using a FTDI based USB to Serial Converter ( USB2SERIAL)which is recognized as COM24 (this may be different under your system). If your PC has any hardware ports, it will be shown either as COM1 or COM2 under the Ports Section. Under Ports(COM & LPT) you can see the parallel and serial ports (COM) detected by your system.
by typing "Device Manager" on the taskbar search box in Windows 10.Open Device Manager by right clicking on My Computer icon and selecting Manage → Device Manager.
To find out the COM number corresponding to your serial port, etc are given to USB to Serial Converters or PCI serial port extenders. While COM numbers in double digits like COM32, COM54,COM24. COM1 and COM2 usually refer to the hardware serial ports present in the PC (quite rare now) Serial ports are named as COM1, COM2 ,COM3. If your PC does not have any hardware serial ports (RS232 DB9 ports), you can use USB to Serial Converter's like USB2SERIAL.
The arrival of cheap USB to UART chips like FTD FT232RL,TUSB3410,CP2102 have made it quite easy to upgrade the existing software that used to talk over serial to USB protocol.These chips provide a virtual serial port that behaves like a real one but transmits the data through USB. In the 2020's, the old DB9 Serial port is found only on industrial motherboards and old PC's.The once ubiquitous serial port have been completely replaced by the familiar USB standard. The simple protocol and the 3 pin hardware physical lines (RX,TX,GND) made it quite popular among manufacturers who wanted an easy way to connect their devices with a computer. Serial ports are simple 9 pin legacy ports used by the PC to communicate with external peripherals like Printers,Data Acquisition Sytems,Printers etc. Make sure that variables referenced by those functions are also changed. Which are used to get the COM number from the user and create the COM port address string (Eg "\\.\COM9" ).The code will compile on GCC after removing those functions. The Code uses some Microsoft specific safe C functions like
You can also compile the code using GCC or MinGW after a few tweaks. C extension (Eg: MySourceFile.C).Compiler would automatically do the rest. So create a Win32 C++ project and save your source file with a. In Visual Studio,there is no longer an option for creating a C project.
This tutorial teaches you to program your Windows PC to communicate with an external peripheral like data acquisition boards, USB GPIO Boards,Relay boards etc through its serial port (Virtual or Real).