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Siemens Building Technologies Basic Documentation RVL471 CE1P2524E
HVAC Products 4 Acquisition of measured values 23.10.2002
4 Acquisition of measured values
4.1 Room temperature (A6, B5)
4.1.1 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
• 2 units can be connected to the terminals. In this case, the RVL471 can ascertain the
average of the 2 measurements. The other room unit functions will not be affected by
averaging
4.1.2 Handling faults
If there is a short-circuit or open-circuit in one of the 2 measuring circuits, the control
responds as follows, depending on the room temperature source (setting on operating
line 65):
• No sensor (operating line 65 = 0):
A short-circuit or open-circuit has no impact on the control. An error 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 with the
room model, depending on the function. An error 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 with the
room model, depending on the function. An error message will be generated
• Average value (operating line 65 = 3):
In the event of a short-circuit or open-circuit in one of the 2 measuring circuits, the
control continues to operate with the normally working measuring circuit. An error
message will be generated.
In the case of a short-circuit or open-circuit in both measuring circuits, the control con-
tinues to operate with the room model, depending on the function. 2 error messages
will be generated
• Automatic mode (operating line 65 = A):
Since the controller itself decides how it acquires the room temperature, error mes-
sages cannot be generated.
4.1.3 Room model
The RVL471 features a room model. It simulates the progression 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 detailed information, refer to section 10.4.4, "Room model temperature".
4.2 Flow and boiler temperature (B1)
4.2.1 Measurement
The flow or boiler temperature is acquired with one or 2 sensors. 2 sensors connected
in parallel are used to ascertain the average value. The temperature sensors used must
always have a sensing element LG-Ni
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