Drawing a dataflow using tikz

Question

I'm trying to draw the following dataflow diagram in tikz:

Here is what I got so far:

\documentclass[10pt,a4paper]{article}
\usepackage[english]{babel}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{decorations.markings,positioning,petri}
\begin{document}
\begin{tikzpicture}[thick,
    node distance=2cm,
    on grid,
    every transition/.style={fill=black,minimum width=.1cm, minimum height=0.9cm},
    every label/.style={black!75}]
    node distance=2cm,
    on grid,
    every transition/.style={fill=black,minimum width=.1cm, minimum height=0.9cm},
    every label/.style={black!75}]
  \node[place, label=above:$n_1$] (n1) {+};
  \node[place, right=of n1, label=above:$n_2$] (n2) {$\times 2$};
  \node[place, right=of n2, label=above:$n_3$] (n3) {+};
  \node[place, below=of n2, label=above:$n_4$] (n4) {+1};
  \node[place, right=of n3, label=above:$n_5$] (n5) {$\Delta(0)$};
  \node[right of=n5] (x) {X};
  \node[below of=n5] (y) {Y};
  \node[left of=n1] (i) {Input};
\draw[->] (n1) edge (n2.west);
  \draw[->] (n2) edge (n3.west);
  \draw[->, to path={-| (\tikztotarget)}] (n4) edge (n3.south);
  \draw[->] (n3) edge (n5.west);
  \draw[->] (n5) edge (x);
  \draw[->] (n4) edge (y);
  \draw[->] (i) edge (n1.west);
  \draw[->, to path={|- (\tikztotarget)}] (i) edge (n4.west);
\end{tikzpicture}
\end{document}

As you can see, drawing the nodes work fine but I'm having trouble getting the edges right. I want the edges to be angled and also there to be dots so it's clear where the flow branches.

I updated my code with edge drawing commands. I still cannot get the feedback edge right nor do I get dots where the edges branches.

Answer 1

Try the following:

%\documentclass[10pt,a4paper]{article}
\documentclass[border=3.141592mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                chains,
                decorations.markings,
                positioning,
                shadows, }
\begin{document}
    \begin{tikzpicture}[
node distance = 7mm and 11mm,
  start chain = A going right,
     C/.style = {circle, minimum size=11mm, inner sep=1pt, outer sep=0pt,
                 draw, semithick, fill=gray!30},
   dot/.style = {circle, fill, inner sep=2pt, outer sep = 0pt,
                 node contents={}},
every label/.style = {font=\small\sffamily},
 every path/.style = {-Straight Barb}
                        ] 
\coordinate[label=above right:input] (in);
\node (d1) [dot, right=of in];
    \begin{scope}[nodes = {C, on chain=A, join=by ->}] 
\node (n1) [C, right=of d1]   {+};  % A-1
\node (n2) [C]   {$\times 2$};
\node (n3) [C]   {+};
\node (n4) [C]   {$\Delta(0)$};     % A-4
    \end{scope}
\node (d2) [dot, right=of A-4];
\coordinate[right=of d2, label=above left:X] (x);
%
\node (A-5) [C, below=of A-2] {+1};
\node (d3)  [dot, at={(A-5 -| A-3)}];
\coordinate[right=of d3, label=above left:Y] (y);
%
\draw   (d2) |- ([yshift=7mm] A-1.north) edge (A-1)
        (in) to (A-1) (d3) edge (A-3)   (A-4) edge (x)
        (A-5) edge (y);
\draw   (d1) |- (A-5);
\end{tikzpicture}
\end{document}

Edit: Ar adding labels the chain had to be handled different as above: it should be add to C nodes style. Doing this, macro join had to be interrupted because it should not connect last Cnode in code with others. In this case thescope` is not needed anymore.

\documentclass[border=3.141592mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                backgrounds,
                chains,
                positioning}
\makeatletter
\tikzset{suspend join/.code={\def\tikz@after@path{}}}
\makeatother
\begin{document}
    \begin{tikzpicture}[
node distance = 7mm and 11mm,
  start chain = going right,
     C/.style = {circle, minimum size=11mm, inner sep=1pt, outer sep=0pt,
                 draw, semithick, fill=gray!30, drop shadow,
                 on chain, join= by ->},
   dot/.style = {circle, fill, inner sep=2pt, outer sep = 0pt,
                 node contents={}},
every label/.style = {label distance=5pt, inner sep=1pt, 
                      font=\small\sffamily, fill=white},
 every path/.style = {-Straight Barb}
                        ]
\coordinate[label=above right:input] (in);
\node (d1) [dot, right=of in];
\node (n1) [C,label=$n_1$,
            right=of d1]    {+};

\node (n2) [C,label=$n_2$]  {$\times 2$};
\node (n3) [C,label=$n_3$]  {+};
\node (n4) [C,label=$n_4$]  {$\Delta(0)$}; 
\node (d2) [dot, on chain];
\coordinate[on chain, 
            label=above left:X] (x);
\node (n5) [C, suspend join,
            below=of n2,
            label=$n_5$]   {+1};
\node (d3) [dot, at={(n5 -| n3)}];
\coordinate[right=of d3, label=above left:Y] (y);
%
\scoped[on background layer]
\draw   (d2) |- ([yshift=7mm] n1.north) edge (n1)
        (in) to (n1) (d3) edge (n3)   (n4) edge (x)
        (n5) edge (y);
\draw   (d1) |- (n5);
    \end{tikzpicture}
\end{document}