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POHow can I send null characters to the serial port using the Windows API?
 

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  1. POHow can I send null characters to the serial port using the Windows API?
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    <p>I am working on a Windows utility program which communicates with some custom hardware using a standard COM port. The communication protocol (which is out of my control) requires me to transmit and receive raw 8-bit data bytes.</p> <p>I am currently using the following Windows API function to send data to the COM port:</p> <pre><code>WriteFile(hFile, lpBuffer, numberOfBytesToWrite, ...)</code></pre> <p>where <code>hFile</code> is a reference to the properly opened COM port, and <code>lpBuffer</code> is an array of bytes that I have stored in memory. The code works perfectly until a null character (ASCII zero) needs to be sent to the device. <code>WriteFile</code> stops sending as soon as it detects the null character because it assumes that it has reached the end of the string. This happens even though I set <code>numberOfBytesToWrite</code> properly.</p> <p>How can I send raw data to the COM port using the Windows API? I would prefer to use a standard API call similar to <code>WriteFile</code>, but I am open to suggestions.</p> <p>I am currently using <a href="http://rapidqwiki.altervista.org/" rel="nofollow noreferrer">RapidQ</a> to build the utility, but all it does is call the Windows API function directly.</p> <p><b>Edit:</b> My setup consists of a Windows PC connected via serial port to the custom hardware module. The module has a small screen on which I am able to view the transmitted characters. I have tested this setup with another third-party utility program. I am able to communicate with the module using this third party program, and null characters show up properly. In my own program, when I use <code>WriteFile</code>, a null character anywhere in the transmit stream stops the rests of the stream from being sent.</p>
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    1. COI've just received the "Popular Question" badge for this question, which suggests that it contains some popular search terms. Judging by the number of votes, however, it is not *at all* useful to the vast majority of the people who arrive here. Should we do something to improve this situation? Delete the question, perhaps? I'm open to suggestions.
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    2. COUpdate: I have opened a [Meta discussion](http://meta.stackexchange.com/q/67793/134491) to address the issue.
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