Hello Roland,

Your 1st schema is wrong !!!

Because you are connecting the upper "rt" socket with the "E" socket on the SAME POWER LINE (DC PS). This is wrong because the upper "rt" socket is the digital signal, thus you are connecting together a digital signal and a dc power -> Guaranteed smoke

Here is the translation of the 5211 manual (old version of 2011):

Attention!
In case of separate switching voltage supply (according to figure 2) do not connect the red wire "E" and the red cable of the digital circuit together! Only the ground lines (brown) are coupled.

However, the red socket "E" must always be connected according to either figure 1 or figure 2, otherwise the decoder cannot generate voltage pulses at its outputs..

In your case, the upper "rt" and "bn" socket should be connected to other 5211 (lower "rt" and "bn" sockets), or left unconnected, and the "E" socket connected to other "E" socket.

Here is an example ...


Cheers
Fabrice

PS: in addition, I attach my old 5211 doc viesmann-5211.pdf (403kb) downloaded 24 time(s).

Got it - glad I asked to confirm . Thank you both for the reply and the diagram.