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Siemens
RDU341 Basic Documentation
CE1P3172en
Building Technologies
2015-06-08
3.11.2 Description of communication objects
Obj
Object name
Function
Type/ length
Flags
1
System time
Time and
date
19.001
8 Byte
CWU
System time for display on the room thermostat. See parameter
P07 (3 or 4)
3
Time of day
Time and
date
10.001
3 Byte
CWU
Another object for receiving the time of day for display on the room
thermostat. See parameter P07 (3 or 4)
4
Fault information
Alarm
Info
219.001
6 Byte
CT
Common alarm output. If an alarm occurs, the alarm number is
transmitted
5
Fault state
Faulty /
normal
1.005
1 bit
CT
Common alarm output. If an alarm occurs, the alarm flag is set
6
Fault
transmission
Enable /
disable
1.003
1 bit
CWU
A supervisor alarm system can disable the broadcasting of alarms
by the devices. This has no impact on the local display of alarms.
After a timeout of 48 hours, the sending of faults will automatically
be enabled again.
7
Room operating
mode:
Preselection
Auto
Comfort
PreComf.
Economy
Protection
20.102
1 Byte
CWTU
Controls the room operating mode selection of the thermostat via
bus.
The command can also be submitted as four 1-bit communication
objects (8...11). The last interaction wins – either from local
operating mode button or via bus.
Note: The thermostat will transform Precomfort either into
Economy or Comfort (selectable via P88).
8
9
10
11
Operating mode:
Preselection
Auto
Comf
Eco
Prot
Trigger
1.017
1 bit
CW
Switch room operating mode to either Auto, Comfort, Economy or
Protection.
The last interaction wins – either from the local operating mode
button or via bus.
12
Room operating
mode: Time
switch
Comfort
Economy
PreComf.
Protection
20.102
1 Byte
CWU
This information is provided by a central time switch or a
supervisor and defines the actual HVAC operating mode.
The command can also be submitted via three 1-bit
communication objects (13...15).
Protection has the highest priority and cannot be overridden.
Note: The thermostat will transform Precomfort either into
Economy or Comfort (selectable P88).
13
14
15
Time switch
Comfort
Economy
Protection
Trigger
1.017
1 bit
CW
Switch the HVAC mode to either Comfort, Economy or Protection
mode.
Obj
Object name
Function
Type/ length
Flags
16
Room operating
mode: State
Comfort
Economy
Protection
20.102
1 Byte
CRT
Effective room operating mode used by the thermostat
(considering time switch, user selection, window contact, etc.) This
state information is available via one 8-bit enumeration or three 1-
bit communication objects (17...19). Note: The thermostat does not
support Precomfort.
17
18
19
Room operating
mode:
State Comfort
State Economy
State Protection
ON
OFF
1.002
1 bit
CT
Corresponding communication object sends "True"
20
Window state
Open
Closed
1.019
1 bit
CWU
The thermostat is set to Economy mode if value “1” (open) is
received. It switches back to the previous mode when the value is
“0” (closed).
"Window state" is sent e.g by a KNX switch or a KNX presence
detector. It has the same effect as the local operating mode
switchover contact X1, X2 (parameter P38, P40).
Only one input source must be used, either local input X1/X2 or
KNX bus.
21
Room temperature
Temp.
value
9.001
2 Bytes
CRT
The value of the room temperature measured via built-in or
external sensor is available via this communication object.
22
Room temperature:
Comfort basic
setpoint
Temp.
value
9.001
2 Bytes
CWU
If function "Temporary setpoint" is enabled via parameter P69, then
after an operating mode change, the setpoint adjustments made by
the user and via communication object 23 will be dismissed and
the thermostat will be reset to the Comfort basic setpoint.
Note: Setpoints that have been changed via the local HMI may be
overwritten during a system startup from a central master
controller, e.g.RMB795.
The Comfort basic setpoint is stored in EEPROM (see section
3.3.2).
à
The service life of the EEPROM depends on the number
of write cycles. Never write this communication object cyclically!
23
Room temperature:
Comfort setpoint
Temp.
value
9.001
2 Bytes
CWTU
Communication object used to shift the setpoint used by the
thermostat (see section 3.3.2). Same priority as local setpoint shift
on the thermostat. The last intervention wins.
Note: The Comfort basic setpoint (object 22) will not be changed.
24
Room temperature:
Current setpoint
Temp.
value
9.001
2 Bytes
CRT
Current setpoint, including shift, compensation, etc., used by the
thermostat for temperature control
25
Control output
VAV
0…100% 5.001
8 bit
CRT
Indicates the position of the air damper. E.g. single duct
26
Heating output
primary
0…100% 5.001
8 bit
CRT
Indicates the position of the heating actuator of the auxiliary
heating. E.g. single duct with electric heater application: Output of
the electric heater.
