My suggestion is to use an application with a GUI, ie., Dia. The application can export to LATEX PGF macro's. "Dia is a GTK+ based diagram creation program for GNU/Linux, MacOS X, Unix, and Windows, and is released under the GPL license." (https://wiki.gnome.org/action/show/Apps/Dia?action=show&redirect=Dia).
You can easily include the diagram as follows in your document, for example:
\usepackage{tikz}
\begin{document}
\vspace{1em}
\begin{figure}[bth]
\centering
\input{connect-two-blocks.pgf}
\caption[Connect two blocks]{Connect two blocks.}
\label{fig:connecttwoblocks}
\end{figure}
\end{document}
The pgf file below contains the connecttwoblocks figure drawn with Dia. Note that the size of the text "Valx" and "Name" can be adjusted with the scale property [framed,scale=0.7,every node/.style={scale=0.8}].
\ifx\du\undefined
\newlength{\du}
\fi
\setlength{\du}{15\unitlength}
\begin{tikzpicture}[framed,scale=0.45,every node/.style={scale=0.8}]
\pgftransformxscale{1.000000}
\pgftransformyscale{-1.000000}
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\fill (7.350000\du,2.350000\du)--(7.350000\du,15.500000\du)--(18.350000\du,15.500000\du)--(18.350000\du,2.350000\du)--cycle;
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{{1.000000\du}{1.000000\du}}{0\du}
\pgfsetdash{{1.000000\du}{1.000000\du}}{0\du}
\pgfsetmiterjoin
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (7.350000\du,2.350000\du)--(7.350000\du,15.500000\du)--(18.350000\du,15.500000\du)--(18.350000\du,2.350000\du)--cycle;
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node at (12.850000\du,9.120000\du){};
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\fill (8.950000\du,4.300000\du)--(8.950000\du,6.550000\du)--(16.550000\du,6.550000\du)--(16.550000\du,4.300000\du)--cycle;
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{}{0pt}
\pgfsetdash{}{0pt}
\pgfsetmiterjoin
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (8.950000\du,4.300000\du)--(8.950000\du,6.550000\du)--(16.550000\du,6.550000\du)--(16.550000\du,4.300000\du)--cycle;
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node at (12.750000\du,5.620000\du){Val1};
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\fill (9.025000\du,7.350000\du)--(9.025000\du,9.750000\du)--(16.475000\du,9.750000\du)--(16.475000\du,7.350000\du)--cycle;
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{}{0pt}
\pgfsetdash{}{0pt}
\pgfsetmiterjoin
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (9.025000\du,7.350000\du)--(9.025000\du,9.750000\du)--(16.475000\du,9.750000\du)--(16.475000\du,7.350000\du)--cycle;
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node at (12.750000\du,8.745000\du){Val2};
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\fill (9.025000\du,10.550000\du)--(9.025000\du,13.100000\du)--(16.475000\du,13.100000\du)--(16.475000\du,10.550000\du)--cycle;
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{}{0pt}
\pgfsetdash{}{0pt}
\pgfsetmiterjoin
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (9.025000\du,10.550000\du)--(9.025000\du,13.100000\du)--(16.475000\du,13.100000\du)--(16.475000\du,10.550000\du)--cycle;
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node at (12.750000\du,12.020000\du){Val3};
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node[anchor=west] at (7.700000\du,1.600000\du){Name1};
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\fill (23.905000\du,2.275000\du)--(23.905000\du,15.425000\du)--(34.905000\du,15.425000\du)--(34.905000\du,2.275000\du)--cycle;
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{{1.000000\du}{1.000000\du}}{0\du}
\pgfsetdash{{1.000000\du}{1.000000\du}}{0\du}
\pgfsetmiterjoin
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (23.905000\du,2.275000\du)--(23.905000\du,15.425000\du)--(34.905000\du,15.425000\du)--(34.905000\du,2.275000\du)--cycle;
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node at (29.405000\du,9.045000\du){};
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\fill (25.505000\du,4.225000\du)--(25.505000\du,6.475000\du)--(33.105000\du,6.475000\du)--(33.105000\du,4.225000\du)--cycle;
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{}{0pt}
\pgfsetdash{}{0pt}
\pgfsetmiterjoin
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (25.505000\du,4.225000\du)--(25.505000\du,6.475000\du)--(33.105000\du,6.475000\du)--(33.105000\du,4.225000\du)--cycle;
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node at (29.305000\du,5.545000\du){Val1};
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\fill (25.580000\du,7.275000\du)--(25.580000\du,9.675000\du)--(33.030000\du,9.675000\du)--(33.030000\du,7.275000\du)--cycle;
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{}{0pt}
\pgfsetdash{}{0pt}
\pgfsetmiterjoin
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (25.580000\du,7.275000\du)--(25.580000\du,9.675000\du)--(33.030000\du,9.675000\du)--(33.030000\du,7.275000\du)--cycle;
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node at (29.305000\du,8.670000\du){Val2};
\definecolor{dialinecolor}{rgb}{1.000000, 1.000000, 1.000000}
\pgfsetfillcolor{dialinecolor}
\fill (25.580000\du,10.475000\du)--(25.580000\du,13.025000\du)--(33.030000\du,13.025000\du)--(33.030000\du,10.475000\du)--cycle;
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{}{0pt}
\pgfsetdash{}{0pt}
\pgfsetmiterjoin
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (25.580000\du,10.475000\du)--(25.580000\du,13.025000\du)--(33.030000\du,13.025000\du)--(33.030000\du,10.475000\du)--cycle;
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node at (29.305000\du,11.945000\du){Val3};
% setfont left to latex
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\node[anchor=west] at (24.650000\du,1.700000\du){Name2};
\pgfsetlinewidth{0.100000\du}
\pgfsetdash{}{0pt}
\pgfsetdash{}{0pt}
\pgfsetbuttcap
{
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetfillcolor{dialinecolor}
% was here!!!
\pgfsetarrowsend{stealth}
\definecolor{dialinecolor}{rgb}{0.000000, 0.000000, 0.000000}
\pgfsetstrokecolor{dialinecolor}
\draw (16.599699\du,5.402364\du)--(25.505000\du,5.350000\du);
}
\end{tikzpicture}