Added documentation of FMI in TLMSimulator documentation.

Documentation/Impl_FMI.tex

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+\chapter{Functional Mock-up Interface TLM Plugin}
+Functional Mock-up Interface (FMI) is a tool-independent standard for connecting simulation tools \cite{blochwitz2009}. 
+One tool can export a model as a Functional Mockup Unit (FMU), a ZIP package with the file extension FMU. 
+This file is in turn loaded by the master simulation tool, which can connect and simulate the model.
+An FMU file contains a model description XML file called \texttt{modelDescription.xml}, binaries for different platforms and other optional content.
+It is important that the FMU contains a binary file for the platform where the master simulation tool is executed.
+
+There are two versions of the FMI standard: FMI for Co-Simulation and FMI for Model Exchange.
+The main difference is that FMUs for Co-Simulation contain their own built-in solvers, and only exchange data at predefined communication points.
+FMUs for Model Exchange require a solver in the master simulation tool.
+
+The TLM framework is able to simulate aggregated systems of connected sub-models using asynchronous TLM communication. 
+Input, output and bidirectional interfaces are supported.
+Bidirectional interfaces can be either 1D or 3D.
+It is also possible to specifiy physical domains such as mechanical, rotational or hydraulic.
+Including FMUs in the TLM framework requires a wrapper.
+\texttt{FMIWrapper} is a generic wrapper for connecting functional mockup units (FMUs) to the TLM framework.
+It uses the FMI Library from Modelon \cite{modelon2015} to load an FMU, and the TLMPlugin for socket communication with the framework, see figure \ref{fig:overview}.
+
+\begin{figure}[ht]
+\begin{tikzpicture}
+\def\dx{0.0495*\textwidth}
+
+\node[rectangle,draw,thick, 
+      minimum width=5*\dx, 
+      minimum height=5*\dx, 
+      text depth=5*\dx-20pt] () {FMIWrapper};
+
+\node[rectangle, draw, thick, 
+      minimum width=3*\dx, 
+      minimum height=3*\dx, 
+      xshift=2.5*\dx,
+      fill=white] (tp1) {TLMPlugin};
+
+\node[rectangle, draw, thick, 
+      minimum width=3*\dx, 
+      minimum height=3*\dx, 
+      xshift=-2.5*\dx,
+      fill=white] (fl) {FMILibrary};
+
+\node[rectangle, draw, thick, 
+      minimum width=3*\dx, 
+      minimum height=3*\dx, 
+      xshift=-7.5*\dx] (fmu) {xmodel.fmu};
+
+\node[rectangle, draw, thick, 
+      minimum width=3.5*\dx, 
+      minimum height=5*\dx, 
+      text depth=5*\dx-20pt,
+      xshift=9.25*\dx,
+      fill=white] () {TLMManager};
+
+\node[rectangle, draw, thick, 
+      minimum width=3*\dx, 
+      minimum height=3*\dx, 
+      xshift=7.5*\dx,
+      fill=white] (tp2) {TLMPlugin};
+
+\draw[thick,->,very thick] (fmu) edge[bend left] (fl);
+\draw[thick,<-,very thick] (fmu) edge[bend right] (fl);
+\draw[thick,->,very thick] (fl) edge[bend left] (tp1);
+\draw[thick,<-,very thick] (fl) edge[bend right] (tp1);
+\draw[thick,->,very thick] (tp1) edge[bend left] (tp2);
+\draw[thick,<-,very thick] (tp1) edge[bend right] (tp2);
+\end{tikzpicture}
+\caption{FMIWrapper uses FMILibrary to import FMUs, and TLMPlugin for socket communication.}
+\label{fig:overview}
+\end{figure}
+
+Both FMI for co-simulation and FMI for model exchange are supported. 
+Model exchange requires a solver in the wrapper executable.
+For this reason, the CVODE and IDA solvers from the Sundials package are included.