Viessmann VITOCAL 300-A Installation And Service Instructions Manual page 74

Installation sequence
Electrical connections in the control unit
PCB 3 (sensor PCB)
X1 Sensor connections and KM BUS:
& Outside temperature
& Heating water buffer cylinder
temperature
& Boiler temperature, external
heat source
& Flow temperature, heating cir-
cuit with mixer M2
&
System flow temperature
& Secondary flow temperature
& DHW cylinder temperature, top/
bottom
& Remote control connection for
heating circuits with/without
mixer A1, M2, M3
74
(cont.)
X2 Common earth connection (GND)
X5 Terminal for electrical connecting
cable (LV)