https://forge.codesys.com/forge/talk/Engineering/thread/b5cadfa4c6/2020-06-03T16:11:06.581000ZRecent posts to Extending a library function in an application and getting Interface conversion errors2020-06-03T16:11:06.581000Z2020-06-03T16:11:06.581000Zaliazzzhttps://forge.codesys.com/u/aliazzz/https://forge.codesys.com193f3d13d0249b3fdbbb4169b49a4b201fe62480

<div class="markdown_content"><p>Send us a .projectarchive so we can check.</p></div>

2020-06-03T00:59:17.689000Z2020-06-03T00:59:17.689000Zjtebokkelhttps://forge.codesys.com/u/jtebokkel/https://forge.codesys.com368cb778f81b96a22c4bd8af9f78ae2a442b394c

<div class="markdown_content"><p>I have an issue where I have extended a function block from a library, but when I try to use it with the library defined interfaces I get the attached error.</p> <h3 id="error-text">Error Text</h3> <div class="codehilite"><pre><span></span><span class="o">[</span><span class="n">ERROR</span><span class="o">]</span><span class="w"> </span><span class="n">PRS</span><span class="w"> </span><span class="n">Alternator</span><span class="w"> </span><span class="nl">Test</span><span class="p">:</span><span class="w"> </span><span class="n">gAlarmManager</span><span class="p">(</span><span class="n">Line</span><span class="w"> </span><span class="mi">5</span><span class="p">)</span><span class="err">:</span><span class="w"> </span><span class="nl">C0032</span><span class="p">:</span><span class="w"> </span><span class="n">Cannot</span><span class="w"> </span><span class="nf">convert</span><span class="w"> </span><span class="n">type</span><span class="w"> </span><span class="s1">'PceAlarms.IAlarmManager(pcealarms, 0.0.0.1 (powercore engineering))'</span><span class="w"> </span><span class="k">to</span><span class="w"> </span><span class="n">type</span><span class="w"> </span><span class="s1">'IAlarmManager'</span><span class="w"></span> </pre></div> <h3 id="base-fb-declaration-in-library">Base FB Declaration in Library</h3> <div class="codehilite"><pre><span></span><span class="n">FUNCTION_BLOCK</span> <span class="n">AlarmElement</span> <span class="n">IMPLEMENTS</span> <span class="n">IAlarmElement</span><span class="p">,</span> <span class="n">PCI2</span><span class="p">.</span><span class="n">IBasicLogger</span> <span class="p">...</span> </pre></div> <h3 id="extended-fb-declaration-in-project">Extended FB Declaration in Project</h3> <div class="codehilite"><pre><span></span><span class="n">FUNCTION_BLOCK</span> <span class="n">PceAlarm</span> <span class="n">EXTENDS</span> <span class="n">PceAlarms</span><span class="p">.</span><span class="n">AlarmElement</span> <span class="p">...</span> </pre></div> <h3 id="gvl-in-project">GVL in Project</h3> <div class="codehilite"><pre><span></span><span class="n">VAR_GLOBAL</span> <span class="n">fbManager</span> <span class="p">:</span> <span class="n">PceAlarms</span><span class="p">.</span><span class="n">AlarmManager</span><span class="p">;</span> <span class="n">Manager</span> <span class="p">:</span> <span class="n">PceAlarms</span><span class="p">.</span><span class="n">IAlarmManager</span> <span class="p">:</span><span class="o">=</span> <span class="n">fbManager</span><span class="p">;</span> <span class="n">ae000</span> <span class="p">:</span> <span class="n">PceAlarm</span><span class="p">(</span><span class="n">AlarmManager</span><span class="p">:</span><span class="o">=</span><span class="n">Manager</span><span class="p">,</span> <span class="n">alarm</span><span class="p">:</span><span class="o">=</span><span class="n">gAlarm</span><span class="p">.</span><span class="n">xwNULL</span><span class="p">,</span> <span class="p">....</span> </pre></div> <p>How is the interface different when imported from a library vs being used inside the library? Am I doing something wrong? Should I organize the code a different way? Interfaces in their own library?</p></div>