Viessmann VITOTRONIC 200 Service Instructions Manual page 60

Troubleshooting
Messages
(cont.)
Message
Code/system characteris-
tics
CE KM BUS extension
Functions for compo-
nents connected to exter-
nal extension H1 are not
available.
Example:
■ No swimming pool
heating.
■ No switching of lag
heat pumps in a cas-
cade.
■ No external demand/
blocking, external
changeover of operat-
ing status, or external
control of mixers and
pumps.
CF Communication module
No communication via
LON.
60
Cause
Communication fault KM
BUS external exten-
sion H1.
LON communication
module not plugged in or
faulty.
Measures
Check external exten-
sion H1 connections and
connecting cables.
Check connection aVG
KM BUS (see page 172).
A fluctuating DC voltage
between approx. 20 V and
30 V can be measured at
the terminals.
If required, replace com-
ponents in the following
order:
■ LON communication
module.
■ Controller and sensor
PCB (see page 172).