Prioritization Of Load Sources; Emergency Operation With Several Load Controllers; Manual Control - Siemens LMV37.4 Series Basic Documentation

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Building Technologies Division
Industry Sector

9.7 Prioritization of load sources

To simplify the system's configuration, the load source must be selected. The system
automatically detects the available load sources and selects them. If several load
sources are connected, they are selected according to the following priorities:
Parameter 942 Priority
1 highest
1 2
2 3
3 4
4 5
5 6 lowest
Note!
When the Switching back to pilot function is used, the load controller inputs OPEN
CLOSE (X5-03 pin 2 and 3) are not available (refer to chapter Switching back to pilot).
Analog input X64 is used as the power source in this case.
The active load source can be read out via parameter 942.

9.7.1 Emergency operation with several load controllers

By making use of the prioritization described above, it is also possible to implement
emergency operation. Should the building automation and control system fail (provided
parameter 148 is set to undefined (--)), the unit switches automatically over to the
external load controller.
A load controller can be connected via analog input or – if existing – via contacts.

9.7.2 Manual control

If the external load controller via analog input or contacts is not used, a simple manual
output adjustment via switch can be implemented by cutting the connection to the load
controller for switching from automatic to manual operation. In that case, the system
switches to the external load controller via contact. A switch for Open/Close or stage
2/stage 3 can then be connected to the load controller's terminals.
Basic documentation LMV37.4...
9 Connection to load controllers
Active load source
Chapter Controller-ON contact X5-03, pin 1
When the input is activated, the other load
sources are assessed according to their
priorities. When the input is deactivated, the
burner is OFF
Chapter Output with curve settings
Chapter Manual output
Chapter Load controller via building automation
X92
Chapter External load controller via analog input
X64 pin 1/pin 2
Chapter External load controller via contacts X5-
03, pin 2/pin 3
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CC1P7546en
20.09.2013