Alpine WSL Free. ILSpy Free. Ubuntu GWSL Free. What's new in this version Changed Spashscreen. Features Serial Communication. Approximate size Age rating For all ages. This app can serialcommunication. What happens to further data depends upon the configuration that you have set in the device configuration block in call to SetCommState. Usually the applications do some kind of handshaking at the application level but you can also make configurations such that the com port does not accept any further data upon buffer-full events.
But all that is beyond the scope of this discussion. If possible its always better to have applications themselves implementing some kind of handshaking - like do not send next block of data until you get okay for the first block. ReadFile API has to specify how much data to read. Lets say we are monitoring character arrivals and 10 characters arrive at the port. As soon as first character arrives at the port the system will set the overlapped structure's event object and out Copy Code WaitSingleObject will return.
Next we would need to read the data. So how much data should we read? Should we read 1 byte or 10 bytes? That is a good question. The way it works is as follows Note: this is not documented anywhere but this is what I have found by research on Win2K,NT4.
When one or more characters arrive at the port, the event object associated with the overlapped structure set once. Now lets say that you made a call to read and you read 1 character. After reading 1 character , you would finally Reset the overlapped structure's event object.
Now you would go back to the WaitCommEvent but it would return false since no "new" character has arrived. So you will not be able to read any more characters. Now when another character arrives, system will set the overlapped event and you would read one more character but this time it will be the character that had arrived earlier and you never read. This clearly is a problem. So what is the solution?
The easiest solution is that as soon as you got the event object indicating the arrival of a character, you should read all the characters that are present in the port. So again the question remains how many characters to read. The answer is read all the characters in a loop using Copy Code ReadFile.
Here is the pseudo code. The first parameter is as usual the com port, the last parameter is the overlapped structure. Again we need to create a manual reset event and pass the overlapped structure to the ReadFile function. As you can see ReadFile returns dwBytesRead which as is clear returns the number of bytes read.
If there are no bytes remaining, the dwBytesRead will return 0. Lets say there are 11 bytes that have arrived and you read 10 characters in the first go in while loop. In the first go 10 characters will be returned in Copy Code dwBytesRead. In the second go with while loop, the dwBytesRead will return 1. Now in the third go the dwBytesRead will return 0 and you will break out of the while loop.
This allows you to read all the data. In this approach ,if you noticed, we never really took advantage of the overlapped structure that we passed to the ReadFile function but we still need to pass it because we opened the COM port in Overlapped manner.
And finally when you want to send data to other device, you need to call Copy Code WriteFile. WriteFile is not even worth discussing.
There is one more thing that needs to be taken into account before we move on and that is communication timeouts. Its important to set the timeout to proper values for things to work. The API to do so is:. For a description of all these fields consult MSDN documentation. But one thing I want to point out is this:. This is exactly what we want.
A value of zero for both the WriteTotalTimeoutMultiplier and WriteTotalTimeoutConstant members indicates that total time-outs are not used for write operations Now we have discussed almost everything that needs to be discussed for the sake of this article. First of let me show you how to use the class. In your application create an object of CSerialCommHelper like this:.
Init passing in the necessary information. If you want you can use default values. The thread starts "listening" for any incoming data and once the data has been received it reads all the data into a local buffer which is of type Copy Code CSerialBuffer. Once its done reading all the data it sets the event in case you want to get the notification. Now you have three options. There is one more thing that needs to be paid attention. One more thing. If you think I have left something please feel free to email me at ashishdhar hotmail.
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Tagged as VC6. Download day fully-functional trial period. Free Serial Monitoring Utilities Here is our selection of free utilities with their pros and cons that can be used to monitor your serial ports:.
Cons: ability to save data in a text file only. Serial port is shareable!. Haven't found any alternatives for the bit environment. This tool allows to work with virtual machine and this is really helpful for my work! Pros: virtual machine. SerialMon: SerialMon is also freeware but is not open-source. Cons: the free version of this application limits you to five monitoring sessions per day with the maximum time per session set at 20 minutes; grace period 4 day. Pros: it allows you to perform remote monitoring, log data to a file, and make use of powerful filtering capabilities; the software includes an online help file that makes the tool more user-friendly; monitoring parallel ports as well as serial activity.
Cons: the last update was on January 12, ; you will only be able to use this utility on systems running Windows NT 4. Many thanks to you all.
I can now send and receive data to the device via USB. Portmon is a great tool to check for serial issues Pros: this tool resides in your Windows notification tray and notifies you when a device is added or removed; it is a simple tool that performs a single function to help you track the devices attached to your system; this freeware was last updated in late and supports Windows Cons: This software just shows the COM ports that are plugged into the computer.
You may be interested in related articles. Proven manual for users. Professional Serial Port Monitoring Software for Windows Professional COM port monitoring applications offer more features and support than do the free tools previously mentioned.
It provides a convenient way to monitor and analyze serial port activity. Win32 API provides WaitCommEvent function used to wait for events which can occur for the specified communications device. At that the set of events checked by this function is contained in the events mask connected with the given device.
HW server HW. January - Work with hardware under Windows API standartizes work with hardware. To get access to hardware the following steps are used: Get Handler of the device by calling CreateFile with the device name.
For more information refer to. Windows SDK Help. Serial port configuration set and request. Reading from or writing into the serial port. Control of the given events set, which could occur for this serial port.
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