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Siemens
QAX33.1 – Room unit with PPS2 interface
CA2N1642en_02
Building Technologies
30 Jun 2009
Installation notes
Local installation regulations must be observed.
The room unit is not protected against connection to AC 230 V.
Commissioning notes
After an interrupt of the PPS2 interface the communication will only be re-established
when the connected controller polls the PPS2 addresses. The duration of the corre-
sponding cycle is:
RXA: 10 sec; RXB, RXL and RXC: 3 min; PX: 30 sec.
The following routine occurs in the room unit when the power supply is connected (via
the PPS2 interface) or after a reset via the controller:
Step Function Description
1
LED test
The LEDs are operated in sequence for 1 s each
2 Device
ready
After a delay of 1 s the device will be ready for PPS2 communi-
cation. The actual control mode is displayed after a further delay
of 5 s.
Technical data
Supply voltage
Operating voltage range
SELV / PELV DC 12 ... 15 V
The room unit receives its power from the connected controller, via the PPS2 interface
Power consumption (from controller)
Max. 0.10 VA
Function data
Temperature sensor
Measuring element
NTC resistor
Measuring range
0 ... 40 °C
Response
time
8 min
Accuracy (5 ... 30 °C)
0.5 K
Accuracy
(25
°C)
0.25 K
Setpoint
correction
Correction range (determined by controller) max.
12 K (default
3 K)
Accuracy over full correction range
10 %
Indication (control mode)
2 LEDs, yellow
Interfaces
Type of interface between controller and
room unit
PPS2
(point-to-point interface, Version 2)
Baud rate
4.8 kbit/s
Cable connections
Connection terminals (screw terminals)
Stranded or solid conductors
0.8 ... 2.5 mm
2
Single cable length controller – Room unit
See Installation guidelines:
DESIGO RXC: CA110334,
DESIGO RXB & RXL: CM110381
DESIGO RXA: CA2Z3884
DESIGO PX: CA110396
Cable type
2-core or 4-core, twisted pairs,
unscreened
Connecting cable for service tool
Off-the-shelf, max. 3 m
Housing protection standard Protection standard to EN 60529
IP 30
Protection class
Insulation protection class
III
STOP
Note!
Response on start-up
