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Siemens
QAX32.1 – Room unit with PPS2 interface
CA2N1641en_03
Building Technologies
2015-12-23
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
corresponding 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
communication. The actual control mode is displayed after a
further delay of 5 s.
Technical data
Supply voltage
Operating voltage range
DC 12...15 V (SELV)
DC 12…15 V class 2 (US)
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
Protection data
Housing protection
IP 30 to EN 60529
Protection class
III to EN 60730-1
Ambient conditions
IEC 721
Operation
Transport
Ambient air conditions
Class 3K5
Class 2K3
Temperature
0 ... 50 °C
– 25 ... 70 °C
Humidity
< 85 %rH
< 95 %rH
Mechanical conditions
Class 3M2
Class 2M2
Response on start-up
