https://forge.codesys.com/forge/talk/CODESYS-V2/thread/ad6368cd3b/2020-02-27T22:11:25.328000ZRecent posts to J1939 TX signal conversion2020-02-27T22:11:25.328000Z2020-02-27T22:11:25.328000Zsgronchihttps://forge.codesys.com/u/sgronchi/https://forge.codesys.com790f2087777a9abb0a6f2d4f19edbb0c32f2da4a

<div class="markdown_content"><p>And if you set "Raw data type" (a.k.a. on the wire) as "Unsigned" and set "Offset" as -180?<br/> It is also more idiomatic (by the J1939 standard, all quantities on the wire are, or at least should be, unsigned).<br/> By the way, if it is an angle, have you checked the standard angle scalings? There is SAEad04 which uses two bytes, 1/128 deg/bit, and offset -200, for a total range of -200 .. +301.99 degrees.</p></div>

2020-02-27T22:11:23.791000Z2020-02-27T22:11:23.791000Zi-campbellhttps://forge.codesys.com/u/i-campbell/https://forge.codesys.coma48589cdb408a3d158c8c33bd46f4ca5d56eee81

<div class="markdown_content"><p>Hmm, it is clear you have a 12bit 2's compliment signed integer, whose data is stored in 16 bit 2's compliment signed integer.</p> <p>You can write a FUNCTION to convert the two data types.</p> <div class="codehilite"><pre><span></span><span class="nv">FUNCTION</span> <span class="nv">SIGNED12_TO_INT</span> : <span class="nv">INT</span> <span class="nv">VAR_INPUT</span>     <span class="nv">Signed12</span> : <span class="nv">INT</span><span class="c1">;</span> <span class="nv">END_VAR</span> <span class="o">//</span><span class="k">IF</span> <span class="nv">Bit</span> <span class="mi">12</span> <span class="nv">is</span> <span class="nv">already</span> <span class="nv">on</span>, <span class="k">then</span> <span class="nv">we</span> <span class="nv">know</span> <span class="nv">it</span> <span class="nv">is</span> <span class="nv">a</span> <span class="nv">negative</span> <span class="nv">number</span> <span class="nv">and</span> <span class="nv">must</span> <span class="nv">convert</span> <span class="k">IF</span> <span class="nv">Signed12</span>.<span class="mi">12</span> <span class="k">THEN</span>     <span class="nv">SIGNED12_TO_INT</span> :<span class="o">=</span> <span class="nv">TO_INT</span><span class="ss">(</span><span class="nv">TO_UINT</span><span class="ss">(</span><span class="nv">Signed12</span><span class="ss">)</span> <span class="nv">OR</span> <span class="mi">16</span>#<span class="nv">F000</span><span class="ss">)</span><span class="c1">; //SET the highest 4 bits</span> <span class="k">ELSE</span>     <span class="nv">SIGNED12_TO_INT</span> :<span class="o">=</span> <span class="nv">Signed12</span><span class="c1">;</span> <span class="nv">END_IF</span><span class="c1">;</span> </pre></div> </div>

2020-02-27T22:11:19.493000Z2020-02-27T22:11:19.493000ZAnonymoushttps://forge.codesys.com/u/*anonymous/https://forge.codesys.com74401ac0b489154ff962d3374917719033a16fd9

<div class="markdown_content"><p><em>Originally created by:</em> palej</p> <p>Hi,</p> <p>I am sending broadcast message and within PGN there is 12 bit signal (Codesys 3.5 SP11+ 32 bit) with conversion info:<br/> Conversion: TRUE<br/> Raw data type: Signed<br/> Byte order: Little endian<br/> Scaling 1<br/> Offset 0<br/> IEC datatype: INT<br/> (min and max values are -180 to 180)<br/> And when "online" the value is e.g. -175.</p> <p>When I am reading that CAN message from other controller and I am watching it Online, the values coming are fine for 0..+180 (same 0..+180), but negative values from -1 to -180 are 3917 to 4095 ?? It's like the Signed is not working?</p> <p>The "reading" controller PGN signal conversions are same :<br/> Conversion: TRUE<br/> Raw data type: Signed<br/> Byte order: Little endian<br/> Scaling 1<br/> Offset 0<br/> IEC datatype: INT</p> <p>"Reading" controller is with Codesys 3.5 SP15 Patch 1 + (64 Bit)</p> <p>Why the value is like it's Unsigned UINT? What I am doing wrong or is it a bug?</p></div>