Thank you,
what I understand is that I should say the worker "connect to a different Port".
Then I have a new problem: I need two workers using the same COM-Port.
I think it is impossible to let two workers connect to the same port.

The reason for the two workers:

With two workers reading & writing is possible at the same time.
With just one worker every read, blocks writing for about one second.
I tried for hours to make it non-blocking and then decided to use threads (and that really worked well).

I am not sure, but I think generating workers first, then Tk has the following reason:
The copy of everything in memory (when generating the threads) disturbs Tk.
(https://www.perlmonks.org/?node_id=585533)
I think the use of fork() would lead to the same Problem

I think the solution i should try, is to have two seperate scripts running (one for Tk and one for the I/O).

Therefore i read a lot about IPC today, but ran into many traps.
Not using fork seems to make "easy" IPC impossible (or am I wrong?)
What is the easiest way to let two seperate Perl-Scripts "talk" to each other?

Unix Domain Sockets seem not to work on Windows.

I am willing to read, learn and try a lot but at moment everything seems to lead to new problems far beyond my knowledge.

EDIT: I found solutions.
No more threads in Tk script...
open3 opens the script (from gui) for serial I/O.
The new difficulty was to read non-blocking from that so gui won't freeze:
Solution: gui asks second script for the number of answers it will deliver, second script answers with number. gui reads just #number times.(so that there is definitly an answer)
Then display, then redo.
Works for now...
But now I have to understand how to work with errors on a script started by "open3"
(But I'm really happy that it is possible)
I love Perl because it really keeps easy things easy and makes impossible things possible.
A workmate asked me "why I learn such an old language" - and I really had enough answers.
No answer for me here but also no "RTFM you idiot" I think thats very special to the Perl community - Thank you all for that.

In reply to Re^2: Tk and threads and Control::CLI- change Port-(Object) in Tk an let workers know by notworx
in thread Tk and threads and Control::CLI- change Port-(Object) in Tk an let workers know by notworx

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