\newwrite, pgfplotstable: Put generated rows together to one pgfplotstable (follow-up question)

Question

I get a Code from @egreg that create rows in outwritten textfiles in a loop.
I need to put all these rows together in 1 pgfplotstable, that means something like

\ifnum\the\filecount=1 \pgfplotstableread[col sep=comma]{data\the\filecount.txt}{\main}\else 
\pgfplotstableread[col sep=comma]{data\the\filecount.txt}{\temp}
% \pgfplotstablevertcat{\main}{\temp}  % <--- Does not work!

How do I have to place the pgfplotstablevertcat-command?

Note that for my main algorithm, I have to charge contents of the preceding rows in subsequent rows. I would therefore leave it for the first time in this elaborate output method. The later main code may be discussed and simplified later.

\documentclass[a4paper]{article}
\usepackage{pgfplotstable}

\newcount\filecount
\newwrite\cisout
\begin{document}

\filecount=1
\def\aaa{file number \the\filecount}%
\loop
\immediate\openout\cisout=data\the\filecount.txt
\immediate\write\cisout{%
111, 222,   \aaa
}
\immediate\closeout\cisout
\ifnum\the\filecount=1 \pgfplotstableread[col sep=comma]{data\the\filecount.txt}{\main}\else 
\pgfplotstableread[col sep=comma]{data\the\filecount.txt}{\temp}
% \pgfplotstablevertcat{\main}{\temp}  % <--- Does not work!
\fi
\advance\filecount by 1
\ifnum\filecount<5
\repeat

\section{The Main Table is incomplete}
\pgfplotstabletypeset[col sep=comma, string type]{\main}

\section{The last Temp-Table}
\pgfplotstabletypeset[col sep=comma, string type]{\temp}

\section{Input Test}
\input{data1.txt} \\
\input{data2.txt}\\
\input{data3.txt}\\
\input{data4.txt}
\end{document}

Answer 1

It works alike this way:

\documentclass[a4paper]{article}
\usepackage{pgfplotstable}

\pgfplotstableset{string type}

\newcount\filecount
\newwrite\cisout
\begin{document}

\filecount=1
\def\aaa{\the\filecount}%
\loop
\immediate\openout\cisout=data\the\filecount.txt
\immediate\write\cisout{%
111, 222,  \aaa
}
\immediate\closeout\cisout
\ifnum\the\filecount=1 \pgfplotstableread[col sep=comma, string type]{data\the\filecount.txt}{\main}%
\else \pgfplotstableread[col sep=comma, string type]{data\the\filecount.txt}{\temp}%
\pgfplotstablevertcat{\main}{\temp}% <--- Does  work!
\fi%
\advance\filecount by 1
\ifnum\filecount<5
\repeat

\section{The Main Table is incomplete}
\pgfplotstabletypeset[col sep=comma, string type]{\main}

\section{The last Temp-Table}
\pgfplotstabletypeset[col sep=comma, string type]{\temp}

\section{Input Test}
\input{data1.txt} \\
\input{data2.txt}\\
\input{data3.txt}\\
\input{data4.txt}
\end{document}