Operating Instructions

Table Of Contents
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Siemens RXB (KNX) application library RXB Description of functions for FC-10, FC-11, FC-12, FC-13 CM110385en_08
Building Technologies Temperature measurement 2013-06-17
7 Temperature measurement
7.1 Room temperature measurement
The value valid for temperature control can originate in various sources:
A room unit via PPS2 7.1.1
An analog sensor via analog input B1 7.1.2
Mean value of several sensors 7.1.3
The bus. 7.1.6
If none of these sources supplies a valid room temperature, the following will happen:
the controller uses the mean value from the effective heating and cooling setpoints
for control until a valid measured value is again received
the controller issues an alarm "Room temp. sensor error"
the bus output sends 0°C
if slaves are connected, they receive an invalid temperatur (327.67°C)
if a room unit is connected to a slave, the slave uses the temperature value of its
room unit when two heartbeat periods have elapsed.
7.1.1 Local temperature sensor at PPS2 interface
PPS2 (CP+, CP-)
QAX3...
RXB2...
10385Z12
If a QAX...room unit (with a PPS2 interface)
is connected to the controller, the room
temperature is measured by the
temperature sensor built into the room unit.
7.1.2 Local temperature sensor at analog input
B1
QAA24
RXB2...
10385Z13
Alternatively, an LG-Ni1000 sensor, type
QAA24, may be connected to analog input B1
of the room controller.
The controller detects automatically whether a room unit or an LG-Ni1000 sensor is
connected. No configuration is required. The basic Room sensor setting can be left
unchanged (see page 121).
Supply temperature sensor for FNC08: see section 7.3.
Sources
Invalid temperature
Note