Using tikz Calc package to add cordinates

Question

I would like to draw the line shown in the right hand side of the attached figure from Node 3 to the line between Node 1 and Node 2.

(Note line with should be same width as all other lines.)

I have tried to use the tikz calc package to work out the correct position for the line. But have been unable to work out the syntax.

The picture on the left has side is what my example code is currently achieving. The end point of the line is being positioned at the west on Node 3 at the y coordinate of the line from Node 1 to Node 2.

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{positioning,calc}

\tikzset{block/.style={rectangle,draw}}

\begin{document}
\begin{tikzpicture}

\node[block] (node1) {node1};
\node[block, right=of node1] (node2) {node2};
\draw (node1.east) -- (node2.west);

\node [block, above=of node1, xshift=-0.5cm] (node3) {node3};
\draw (node3.east) -- +(1.,0) -- (node3.east |- node1);

%\draw (node3.east) -- +(1.,0) -- ($(node3.east)+(1.,0)$ |- node1);

\end{tikzpicture}
\end{document}

Answer 1

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{positioning,calc}

\tikzset{block/.style={rectangle,draw}}

\begin{document}
\begin{tikzpicture}

\node[block] (node1) {node1};
\node[block, right=of node1] (node2) {node2};
\draw (node1.east) -- (node2.west) coordinate[midway] (A);

\node [block, above=of node1, xshift=-0.5cm] (node3) {node3};

\draw (node3.east) -| (A);


\end{tikzpicture}
\end{document}

Answer 2

You do not even need calc for that.

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{positioning}

\tikzset{block/.style={rectangle,draw}}

\begin{document}
\begin{tikzpicture}

\node[block] (node1) {node1};
\node[block, right=of node1] (node2) {node2};
\draw (node1.east) -- (node2.west);

\node [block, above=of node1, xshift=-0.5cm] (node3) {node3};
\draw (node3.east) -- +(1.,0) -- ([xshift=1cm]node3.east |- node1);

\end{tikzpicture}
\end{document}

Answer 3

You only need to modify one code

\documentclass{minimal}
\usepackage{tikz}
\usetikzlibrary{positioning,calc}

\tikzset{block/.style={rectangle,draw}}

\begin{document}
\begin{tikzpicture}

\node[block] (node1) {node1};
\node[block, right=of node1] (node2) {node2};
\draw (node1.east) -- (node2.west);

\node [block, above=of node1, xshift=-0.5cm] (node3) {node3};


\draw (node3.east) -- +(1,0) -| ($(node1)!.5!(node2)$);

%\draw (node3.east) -- +(1.,0) -- ($(node3.east)+(1.,0)$ |- node1);

\end{tikzpicture}
\end{document}

($(node1)!.5!(node2)$) Represents the midpoint of two nodes