CE1P2522E / 30.03.2000
Basic Documentation RVL470
Siemens Building Technologies
10/68
Acquisition of measured values
Landis & Staefa Division
4. Acquisition of measured values
4.1.1. Room temperature (A6, B5)
4.1.1.1. Measurement
The following choices exist:
•
A room temperature sensor QAA24 can be connected to terminal B5
•
A room unit QAW50 or QAW70 can be connected to terminal A6
•
A unit can be connected to each of the two terminals. In that case, the RVL470 can ascer-
tain the average of the two measurements.
The other room unit functions will not be affected by averaging
4.1.1.2. Handling of faults
If there is a short-circuit or an interruption in one of the two measuring circuits, the con-
trol will respond as follows:
•
No sensor (operating line 65 = 0):
A short-circuit or open-circuit has no impact on the control. A fault status message will
not be generated
•
Room unit sensor QAW... (operating line 65 = 1):
In the event of a short-circuit or open-circuit, the control continues to operate de-
pending on the function of the room model. A fault status message will be generated
•
Room temperature sensor QAA24 (operating line 65 = 2):
In the event of a short-circuit or open-circuit, the control continues to operate de-
pending on the function of the room model. A fault status message will be generated
•
Average value (operating line 65 = 3):
In the event of a short-circuit or open-circuit in one of the two measuring circuits, the
control continues to operate with the normally working measuring circuit. A fault
status message will be generated.
In the case of a short-circuit or open-circuit in both measuring circuits, the control
continues to operate depending on the function of the room model. Two fault status
messages will be generated
•
Automatic mode (operating line 65 = A):
Since the controller itself decides how it acquires the room temperature, no fault
status messages can be generated
4.1.1.3. Room
model
The RVL470 features a room model which simulates the development of the room tem-
perature. In plants with no measurement of the room temperature, it can provide certain
room functions (e.g. quick setback).
For more details, refer to section "8.4.4. Room model temperature".
4.1.2. Flow and boiler temperature (B1)
4.1.2.1. Measurement
The flow or boiler temperature is acquired with one or two sensors. Two sensors con-
nected in parallel are used to ascertain the average value. The temperature sensors
used must always have a sensing element LG-Ni 1000
Ω
.