Viessmann VITODENS 300 Service Instructions Manual page 98

Function description
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:
sÖ Heating circuit pump for the
heating circuit without mixer
sA Cylinder primary pump
sK DHW circulation pump
fÖ Power supply
gÖ Fault notification
98
(cont.)
aVD External blocking
(terminals 2 - 3)
External demand
(terminals 1 - 2)
External operating mode chan-
geover (terminal 1 - 2)
The allocation of the "External
heating program changeover"
function is selected via coding
address "91".
aVF External set value 0 - 10 V
aVG KM BUS