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Siemens
QAX34.3 – Room unit with PPS2 interface
CM2N1640en_04
Building Technologies
30 Jun 2009
Engineering notes
The room unit receives its power from the connected controller via the PPS2 interface
(low voltage, SELV).
Only one room unit can be connected to an RX... room controller.
When connecting a room unit to a PXC… automation station, the room unit must be
Address 1 (this address is permanently programmed in the room unit).
The room unit must be connected to the room controller with a two-core twisted pair
cable. See the relevant installation guide (RXC: CA110334; RXB & RXL: CM110381;
RXA: CA2Z3884). Unscreened cable may be used.
Mounting instructions
The device is suitable both for surface mounting and for installation in a recessed
conduit box
The unit should not be mounted in recesses, shelving, behind curtains or doors or
above or near direct heat sources
Avoid direct sun and draughts
The conduit must be sealed on the device side, as currents of air in the conduit can
affect the sensor reading
The admissible ambient conditions must be observed.
Mounting instructions are enclosed with the device.
A set of fixing accessories is enclosed with the device.
Installation
Local installation regulations must be observed.
The equipment is not protected against accidental connection to AC 230 V.
Commissioning
After an interruption of the connection to the PPS2 interface, communication is only
re-established when the connected room controller next polls the PPS2 addresses.
The cycle times are as follows:
RXA: 10 seconds; RXB, RXL, and RXC: 3 minutes; PX: 30 seconds
When the supply voltage is connected (via the PPS2 interface) or in the event of a reset
via the room controller, the following routine is executed in the room unit:
Step Function
Description
1 LCD
test All segments of the display module are operated for
approx. 3 s
2 Identification
by controller
Until the controller recognizes the room unit as a PPS2
user, the display reads:
3 Ready
for
operation
1 s after recognition by the controller, the room unit is
ready for operation
STOP
Warning
Start-up
characteristics