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You could use 'mktime()' (<a href="http://www.cplusplus.com/reference/ctime/mktime/" rel="ugc">http://www.cplusplus.com/reference/ctime/mktime/</a>) for that, e.g.<br />
<br />

<pre><code id="code-20-39515952-1">#include &lt;time.h&gt;

uint16_t regtime; // from modbus

struct tm t;

t.tm_mday = regtime &amp; 0x1f;
t.tm_mon = (regtime &gt;&gt; 5) &amp; 0x07 -1;
t.tm_year = (regtime &gt;&gt; 9) &amp; 0x3f + 100; // UNIX date is from 1900

time_t ut = mktime(&amp;t);</code></pre>
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You could use 'mktime()' (http://www.cplusplus.com/reference/ctime/mktime/ [http://www.cplusplus.com/reference/ctime/mktime/]) for that, e.g.



#include <time.h>

uint16_t regtime; // from modbus

struct tm t;

t.tm_mday = regtime & 0x1f;
t.tm_mon = (regtime >> 5) & 0x07 -1;
t.tm_year = (regtime >> 9) & 0x3f + 100; // UNIX date is from 1900

time_t ut = mktime(&t);

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Thanks for great and concise response.<br />
<br />
For tm_mon, I believe bitwise and with 0x0f instead of 0x07.<br />
For tm_year, I believe bitwise and with 0x7f instead of 0x3f.<br />
<br />
In our system, time_t is declared as follows:<br />
typedef &nbsp; &nbsp;unsigned int &nbsp; &nbsp;time_t;<br />
<br />
time_t is only two bytes. &nbsp;Is that sufficent to store unix time ?
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Thanks for great and concise response.

For tm_mon, I believe bitwise and with 0x0f instead of 0x07.
For tm_year, I believe bitwise and with 0x7f instead of 0x3f.

In our system, time_t is declared as follows:
typedef    unsigned int    time_t;

time_t is only two bytes.  Is that sufficent to store unix time ?

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<div class="content wysiwyg-content">
What is Unix Date ?<br />
<br />
Present date is stored in 16-bit modbus register as follows:<br />
<br />
Bits 0 - 4 &nbsp; &nbsp; &nbsp; Day of Month<br />
Bits 5 - 8 &nbsp; &nbsp; &nbsp; Month of Year<br />
Bits 9 - 15 &nbsp; &nbsp; (Year &nbsp;- &nbsp;2000) &nbsp;(0 to 128 &nbsp;== &nbsp;2000 to 2128 )<br />
<br />
<br />
How to conver this date to unix format ?<br />
<br />
Thank you!
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What is Unix Date ?

Present date is stored in 16-bit modbus register as follows:

Bits 0 - 4       Day of Month
Bits 5 - 8       Month of Year
Bits 9 - 15     (Year  -  2000)  (0 to 128  ==  2000 to 2128 )


How to conver this date to unix format ?

Thank you!

How to convert Date to Unix format ?

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