Serge NOEL
189 lines
6.3 KiB
Plaintext
189 lines
6.3 KiB
Plaintext
<!DOCTYPE html>
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<meta name="generator" content="HTML Tidy for HTML5 for Apple macOS version 5.8.0">
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<title>LogixNG Reference - Chapter 4</title>
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<meta name="author" content="Daniel Bergqvist">
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<meta name="author" content="Dave Sand">
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<meta name="keywords" content="jmri LogixNG reference basic actions expressions">
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<h1>LogixNG Reference - Chapter 4</h1>
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<h2>Actions and Expressions</h2>
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<p>LogixNG has four basic building blocks: Actions, Expressions, Male sockets and Female
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sockets.</p>
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<p>Actions do something, for example throw a turnout or sets a signal mast. Expressions ask
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something, for example if a sensor is active or if a signal head has a particular appearance.
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The actions and expressions form a tree and complex logic can be built with them.</p>
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<p>Each action/expression is embedded in one or several male sockets. Male sockets allow
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actions/expressions to be connected to a female socket of the correct type.</p>
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<p>A ConditionalNG has a female socket that is the root of the ConditionalNG tree. And some
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actions/expressions have one or several female sockets as children. There are several
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different types of female sockets and the female socket type decides which types of actions
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or expressions can be connected.</p>
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<h3>Categories</h3>
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<p>Since there is a large number of actions and expressions, they are assigned a category.
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The main categories are <strong>Item</strong>, <strong>Common</strong> and <strong>Flow
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Control</strong>.</p>
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<ul>
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<li>Item - Actions and expressions related to items on the layout, for example turnouts and
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signal masts.</li>
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<li>Common - Important actions and expressions that are not in the Item category, such as
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<strong>Many</strong>, <strong>And</strong>, <strong>Or</strong>, and <strong>Not</strong>.</li>
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<li>Flow Control - Program logic actions and expressions, such as <strong>If Then Else</strong>
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and <strong>Call Module</strong>.</li>
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<li>Display - Actions and expressions related to Panels.</li>
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<li>LocoNet - Actions and expressions related to LocoNet.</li>
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<li>Other - Other actions and expressions.</li>
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</ul>
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<h3>Action and Expression types</h3>
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<p>Each action and expression is built for a specific socket type. <a id=
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"socket_types"></a></p>
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<div style="margin-left: 2em">
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<table>
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<tr>
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<th>Symbol</th>
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<th>Type</th>
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<th>Description</th>
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<th>Categories</th>
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</tr>
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<tr>
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<td style="text-align:center">!</td>
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<td>Digital action</td>
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<td>Execute, no parameter</td>
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<td>Item, Common, Flow Control, Other, Display, LocoNet</td>
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</tr>
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<tr>
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<td style="text-align:center">!b</td>
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<td>Digital boolean action</td>
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<td>Execute using a boolean parameter</td>
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<td>Common</td>
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</tr>
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<tr>
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<td style="text-align:center">!~</td>
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<td>Analog action</td>
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<td>Execute using a double parameter</td>
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<td>Item, Common</td>
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</tr>
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<tr>
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<td style="text-align:center">!s</td>
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<td>String action</td>
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<td>Execute using a string parameter</td>
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<td>Item, Common</td>
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</tr>
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<tr>
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<td> </td>
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<td>
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</td>
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<td>
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</td>
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<td>
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</td>
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</tr>
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<tr>
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<td style="text-align:center">?</td>
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<td>Digital expression</td>
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<td>Return boolean</td>
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<td>Item, Common, Flow Control, Other, LocoNet</td>
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</tr>
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<tr>
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<td style="text-align:center">?~</td>
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<td>Analog expression</td>
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<td>Return a double</td>
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<td>Item, Common</td>
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</tr>
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<tr>
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<td style="text-align:center">?s</td>
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<td>String expression</td>
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<td>Return a string</td>
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<td>Item, Common</td>
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</tr>
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<tr>
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<td style="text-align:center">?*</td>
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<td>Generic expression</td>
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<td>Return an Object</td>
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<td>(Digital, Analog, and String merged)</td>
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</tr>
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</table>
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</div>
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<p>Notes:</p>
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<ul>
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<li><strong>string</strong> is text, such as "hello world"</li>
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<li><strong>boolean</strong> is true or false</li>
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<li><strong>double</strong> is a number, such as 42 or 3.14</li>
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<li><strong>Generic expression</strong> can handle any expression type</li>
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</ul>
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<h3>Adding an action or expression</h3>
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<p>When <strong>Add</strong> is selected from the context menu for an empty socket, the
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category and type sub-menus are displayed.</p>
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<div style="margin-left: 2em">
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<a href="images/chapter4/add_sub_menus.png"><img class="image-border"
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src="images/chapter4/add_sub_menus.png" alt="Chapter 4 add sub menus"></a>
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</div>
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<p>The first sub-menu list contains the <strong>Category</strong> names. The second level
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contains the available <strong>Type</strong> names for the selected category.
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For example, Digital Action socket using the Item category is
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quite long while Analog Action socket using the Common category is short. The Type list
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always displays the valid selections for the socket type and category.</p>
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<p>There are many combinations of socket types, categories. These are described in <a href=
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"chapter5.shtml">Chapter 5 - Actions</a> and <a href="chapter6.shtml">Chapter 6 -
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Expressions</a>.</p>
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<hr>
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<p><a href="chapter5.shtml">Chapter 5 - Action Descriptions</a>
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</p>
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<p><a href="index.shtml">Return to the Reference TOC</a>
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</p>
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