Default Output Via Building Automation - X92 - Siemens LMV27.100x2 Basic Documentation

Building Technologies
9.3 Default output via building automation – X92
To control the LMV27, the BAC system can predefine an output via a bus system. The
Building automation is connected to the LMV27 via the X92 interface.
Burner startup can take place only when contact X5-03 pin 1 is closed (load controller
On / Off).
For more detailed information about the connection of BAC systems to LMV27, refer to
chapter Connection to superposed systems in this document and to the Modbus User
Documentation (A7541).
Minimum positioning step
To avoid unnecessary positioning steps of the actuators when the predefined target
output varies, a minimum positioning step can be set. The LMV27 changes the output
only if the change in target output exceeds the minimum positioning step. The minimum
positioning step only becomes active in modulating operation.
No. Parameter
123.0 Minimum output positioning step: Output building automation
Behavior in the event the building automation and control system fails
If the LMV27 receives no more data from building automation, it delivers the output set
via parameter 148. The time that elapses until communication breakdown is detected
can be set via parameter 142.
No. Parameter
Setback time in the event of communication breakdown
142 Setting values
0 = deactivate
1...7200 s
Predefined output in the event of communication breakdown with building
automation
Setting values:
For modulating operation, the setting range is as follows:
0...19.9 = burner off
20...100 = 20...100% burner output (20 = low-fire position)
148
For multistage operation, use the following settings:
0 = burner OFF
P1...P3 = stage 1...stage 3
Invalid = no output predefined by the building automation in the event of
communication breakdown
Default setting: Invalid
Setting choices:
a) Set default output via parameter 148 to undefined (--)
In the event communication breaks down, the last valid preselected output is
maintained. The next load controller activated in accordance with the priority
(refer to chapter Prioritization of load controller sources) ensures control from
this output position.
b) Set default output via parameter 148 to 0, 20...100% or multistage
If communication breaks down, the output requested by building automation
becomes invalid and the output set via parameter 148 is delivered.
 Note
In that case, outputs via load controllers having a priority lower than building
automation cannot be delivered.
Basic Documentation LMV27...
9 Connection to load controllers
85/219
CC1P7541en
17.12.2018