Viessmann Vitocal 350-A Installation And Service Instructions Manual page 147

Control unit diagnostics
Message
System characteristics Cause
«CC Coding card
«CD KM BUS Vitocom
«CE KM BUS ext. CE
(cont.)
Coding card cannot be
read
Communication error -
KM BUS Vitocom 100
Communication error -
KM BUS external exten-
sion H1
Troubleshooting
Measures
■ Check coding card and
replace if required.
■ Check PCB 2 (main
PCB) and replace if
required.
■ Check programming
unit of heat pump con-
trol unit and connecting
cable; replace if
required.
Check Vitocom 100 con-
nections and connecting
cables.
Check connections
3X1.25 and 3X2.25 KM
BUS. A fluctuating DC
voltage between approx.
20 V and 30 V can be
measured at the termi-
nals.
Check external exten-
sion H1 connections and
connecting cables.
Check connections
3X1.25 and 3X2.25 KM
BUS. A fluctuating DC
voltage between approx.
20 V and 30 V can be
measured at the termi-
nals.
147