
Functions
KNX communications
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4.12.8 Fault and alarms function on KNX
A fault is sent on the bus in the event of a fault (e.g., digital fault input, dewpoint,
communication configuration, etc.).
An RDG2..KN room thermostat monitors the bus and sends a fault, if the fault has
the highest alarm priority. This ensures that the management station does not miss
any alarms.
The alarm with the highest priority is displayed first and sent over the bus if alarms
occur at the same time.
Fault transmission is different in LTE-Mode and S-Mode:
S-Mode
LTE-Mode
Fault state
Alarm info (error code + internal
information)
Fault information (internal information)
Alarm text (default text can be edited
with ACS tool)
The table below shows error codes and default alarm texts.
Priorities Fault
Thermostat Fault information on bus
Display
Error code
Default fault
text
Text
adjustable
1)
-
No fault
---
0
No fault
✓
1
Bus power
supply
2)
BUS
5000
No bus
power
supply
---
2
Device
address error
Addr
6001
>1 id device
address
---
3
Condensation
COND
4930
Condensati
on in the
room
✓
4
External fault
input X1
AL1
9001
Fault input 1
✓
5
External fault
input X2
AL2
9002
Fault input 2
✓
6
External fault
input U1
AL3
9003
Fault input 3
✓
7
Clean filter
reminder
FIL
3911
Dirty filter
✓
1)
Default alarm texts are stored in the thermostat’s non-volatile memory and can
be adjusted using the ACS commissioning tool.
2)
This error is not sent over the bus (because there is no bus, not enough bus
power supply, bus is overloaded or bus signal is distorted).
●
Priority order is #1…7
●
External faults #4…6: If faults are active, the display shows AL1, AL2, AL3,
alternating. Only the fault with the highest priority is sent over the bus.
A supervisor alarm system may command the thermostat to stop sending faults to
the bus via the communication object "Fault transmission" (disable/enable).
This has no impact on the local display of faults.
After a timeout of 48 hours, the sending of faults is automatically enabled again.
Priority of alarms
Fault transmission