Viessmann Vitodens 333 Service Instructions Manual page 97

Extensions for external connections
External extension H1 (accessories)
The external extension is connected
to the boiler control unit via the KM
BUS. The following functions can be
controlled or processed simulta-
neously via the extension:
A
Mains isolator (on site)
sÖ
Heating circuit pump for the
heating circuit without mixer
sK
DHW circulation pump
fÖ
Power supply
gÖ
Central fault message
Function description
(cont.)
aVD
&
External blocking
(terminals 2 - 3)
&
External demand
(terminals 1 - 2)
&
External heating program
changeover (terminal 1 - 2)
The allocation of function
"External heating program
changeover" is set via coding
address "91".
aVF External set value 0 to 10 V
aVG KM BUS
97