Serial library for C++ - Code. Project. Serial communications is needed in several types of applications, but. Win. 32 API isn't a very easy to use API to implement it. Hi, this is chandu Right now i am working with serial port programming in c on visual studio environment i want to know about the program it should read the data on com port and write the data in com port it should include1. I was wondering if anyone could help me get a start on serial port programming. I have no idea where to start actually and examples would be great. I have looked all over the Internet but did not find anything useful. In today’s programming tutorial, I am going to describe some basics about how we can perform serial port communication from our C#.NET applications. Serial communications can be done via either direct to physical serial port. Describes interfacing the Serial (RS-232) Port in relation to both Hardware and Software. The other 240 are of no interest to us when programming RS-232 type. Using C we would set up the vector using the. Things get. even more complicated when you want to use serial communication in an. MFC based program. The classes provided in the library try to make. Its documentation is extensive, because I want. Serial communication is hard and good. After. reading that chapter you'll probably be convinced as well that you. The classes. provided in the library are not the only classes, which handle the. Many other programmers wrote their own classes. I found many of them too inefficient or they weren't robust. MFC programs. I tried to make these. The Serial Programming Guide for POSIX Operating Systems will teach you how to successfully, efficiently, and portably program the serial ports on your UNIX. Each chapter provides programming. Serial Programming/Complete Wikibook. If a good C/C++ guru would like to 'translate' these routines. This article shows how to communicated with Serial Port using C#. Communicating with Serial Port in C#. Serial Port Programming With.NET by phantomboy in technology software. Intro Intro: Serial Port Programming With.NET. Serial ports provide an easy way to communicate between many types of hardware and your computer. I think. most bugs have been solved, but unfortunately I cannot guarantee that. If you find one (or correct a bug), please. I can update the library. There are. several reasons, which I'll try to explain. Some problems are solved. If both endpoints doesn't use the same setting you get garbled. Unfortunately, no class can help you with these problems. The. only way to cope with this is that you understand what these settings. Baudrate, parity, databits and stopbits are often quite. Handshaking is being used to control the. If the sending machine can. It would be nice when the receiving machine could tell. This process of controlling the. No handshaking, so data is always send even if the receiver cannot. This can lead to data loss, when the sender. Of. course this option isn't recommended, but it can be used for. This mode requires that both ports and the. Hardware handshaking is the most. Make sure you have a proper cable, which is. There are a lot of wrong cables around, so make sure. A major drawback of this method is that these. The XOFF/XON characters. CTRL- S/CTRL- Q characters, which cannot be used in the data. This makes software handshaking pretty useless, when. For ASCII data it's pretty useful. Scrolling starts. CTRL- S/CTRL- Q on these, so the user provides its own. These situations are. These types of handshaking are rarely used. If you do need these. Win. 32 API to do that and. Serial I/O is much slower, which causes unacceptable delays. Another problem is that you don't know when the data. Asynchronous programming is. This complexity is the reason that a lot. This. library solves some asynchronous I/O problems by allowing the. This programming model is a. The basic. rule is simple.. All events are send using a windows message, so you. Most GUI applications. Win. Main function to process all messages. Get. Message(& msg,0,0,0)). Of course you can set a timer and check the ports. Unfortunately the Win. API doesn't. fit in this event driven model. It would be easier for GUI. Win. 32 API posted a message to a window when a. The following piece of code. Comm. Event). bool f. Quit = false. . This isn't that bad, but there is another problem with this. The message pump is normally in one. You don't want to pollute that. The handle is probably not even valid at all times, which can. This solution is therefore not recommended. You might be able to. How can we solve this problem for these types of. The answer is in the CSerial. Wnd class. which posts a message to a window (both the message and window can be. This. makes using a serial port in GUI based applications much easier. The answer is pretty simple. It uses a. separate thread, which waits on communication events. If such an event. This is a very common. It's not. the best solution (in terms of performance), but it is suitable for. GUI based communication applications. The communication. The following three classes are available. It is a lot easier to use, because it. It allows the. programmer to mix overlapped and non- overlapped calls, provides. This releases. the main GUI thread from the serial burden. The main disadvantage. You can use blocking calls (the. This. approach is often the best solution in non- GUI applications, such as. NT services. These events are received in the context of this worker thread. If all. processing can be done in this thread, then this is a pretty efficient. You need some kind of thread synchronization, when you need. GUI thread (i. e. However, if. you don't communicate a lot with the main thread, then this class can. It is a. little less efficient, but the performance degradation is minimal. Because it fits perfectly in the. Note that you can use CSerial in GUI based. MFC/WTL based), but then you might block the. This is, of course, bad practice in in a commercial. As long as you know what the. Because this. wrapper is very thin you can also choose to use CSerial. Wnd directly. First. This is pretty. straightforward. The tricky part is actually transmitting and. At last you need to close the serial port and as a. The implementation is very straightforward and looks like this. Make sure. that the header- files of this library are in your compiler's include. All classes depend on the Win. API, so make sure that you have. I try to make all of my programs ANSI and. Unicode compatible, so that's why the tchar stuff is in there. So. far about the header- files. At the top we declare. COM. port. Before you can use it, you need to open the port. Of course. there should be some error handling in the code, but that's left as an. Besides specifying the COM port, you can. If you don't specify. OS buffer sizes are being used (older. KB as the default buffer size, but this. If you need larger buffers, then specify them. Device Manager) are being used as. Call Setup if these settings. If you prefer to use integers. So the following two initializations are equivalent. Setup(CSerial: :EBaud. CSerial: :EData. 8,CSerial: :EPar. None,CSerial: :EStop. Setup(CSerial: :EBaudrate(9. CSerial: :EData. Bits(8). CSerial: :EParity(NOPARITY). CSerial: :EStop. Bits(ONESTOPBIT)). In the latter case, the types are not validated. So make sure that you. Once you know which type of. Setup. Handshaking. Just call the Write. The Write routine will detect. If you. have written Unicode applications (like this one) then you might have. I didn't send a Unicode string. I think that it's pretty. Unicode strings, so you need to send them as binary or. ANSI yourself. Because we are using hardware. Write method won't return until all bytes have been sent. If there is no other side, then you might block. This program is. nice to display how easy it is to open and setup the serial. The more interesting. The same holds for. As we saw in the Hello world example writing to. Receiving. data is a little more difficult. Reading the data is not that hard. That is exactly what causes problems in. There are three common approaches to. Just block until some data arrives on the. Just call Wait. Event without specifying the. This function blocks until a communication event. Easy, but the thread is. This method. is available in most modern operating systems, but the details vary. The trick is to call the Wait. Event. function asynchronously by supplying an overlapped structure, which. Using. Wait. For. Multiple. Objects you can wait until one of the. I think this is the most suitable for most. GUI applications. It's definitely the most efficient option. When you choose to use this option, you'll notice that the. Win. 32 API. Whenever something happens a message is posted to the. Using the. standard message dispatching this message will be processed. This solution fits perfect in the event- driven programming. GUI (both non- MFC and. MFC) applications. Unfortunately, the Win. API offers no support to. The old Win. 16 API uses the Set. Comm. Event. Mask. Enable. Comm. Notification to do exactly this, but these. Win. 32 API. The CSerial class exposes a method. Wait. Event, which will block until an event has. You can (optionally) specify a time- out for this call. I/O is enabled), so it won't block forever if no data. The Wait. Event method can wait for. The following. events can occur on a COM port. EEvent. Break is sent whenever a break was detected on. Only transitions from low to high will generate this event. Note that this. signal is often called CD (carrier detect). This character can be set using. Set. Event. Char method. If you would like to receive the other events then you. Set. Mask method. You can then call Get. Event. Type to obtain the. This function will reset the event, so make sure you. Wait. Event call. Multiple. events can be received simultaneously (i. Never use the == operator to check for events. You get only an event that. It could be a single byte, but. There is only one way to deal with. Just read as much as you can handle (efficiently) and process. If you would like Read to block, then. ERead. Timeout. Blocking. Read always. returns the number of bytes read, so you can determine whether you have. Make sure you always read the entire buffer. EEvent. Recv event to avoid you lose. A typical EEvent. Recv will look something like this. DWORD dw. Bytes. Read = 0. BYTE ab. Buffer. The entire sample code isn't listed. When the application blocks, then it is completely out. Suppose you have created a service which listens on. COM- ports and also monitors a Win. In such a case, you'll need. Win. 32 function for. The synchronization objects are the most efficient. I'll try to explain them. Before you. continue reading I assume you're a bit familiar with the use of the. If you're not. then first read the section about Synchronization in the Win. API. In the next paragraphs, I will show you. Win. 32 synchronization objects. A complete implementation. Overlapped project, which is quite similar to the. Listener project, but it now uses overlapped I/O. This works identical. Listener sample. Then two events are created. The first. event will be used in the overlapped structure. Note that it should. The second. one is an external event, which is used to stop the program. The first. event will be stored inside the OVERLAPPED structure. We can now call the Wait. Event method. in overlapped mode. It is not allowed to. I/O operation on this port, before it has completed, so we. N. Using Windows messages. Most Windows developers are used to receive a Windows message. This fits perfectly in the Windows.
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