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Building Technologies Division  Basic documentation LMV36...  CC1P7544en 
Infrastructure & Citiies Sector  10 Connection to load controllers  25.09.2013 
 
Behavior in the event the building automation and control system fails 
 
If the basic unit system receives no more data from the system, 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 
142  Setback time in the event of communication breakdown 
 
Setting value: 
0 = inactive 
1…7200 s 
148  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 
 
For multistage operation, use the following settings: 
0 = burner OFF, P1, P2, P3 
Invalid = no output predefined by the BAC system in the event of 
communication breakdown 
 
Default setting: Invalid 
149  Fuel 1: 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 
 
For multistage operation, use the following settings: 
0 = burner OFF, P1, P2, P3 
Invalid = no output predefined by the BAC system in the event of 
communication breakdown 
 
Default setting: Invalid 
 
Setting choices: 
a)  Output preset with parameter 148 set 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 sources) ensures control from this output 
position. 
b)  Output preset via parameter 148 set to 0, 20…100%, or parameterized as 
multistage: 
If communication breaks down, the output requested by the BAC system is set 
invalid and the output set via parameter 148 is delivered. 
 
Note 
In that case, outputs via load controllers with a priority lower than that of the 
BAC system cannot be delivered.