Viessmann Vitodens 200 Service Instructions Manual page 91

Extensions for external connections . . .
External extension H1
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
sA Cylinder primary pump
sK DHW circulation pump (only for
weather-compensated opera-
tion)
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 (terminals 1 - 2)
(only for weather-compen-
sated operation)
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
91