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Building Technologies   Basic documentation LMV37.4...  CC1P7546en 
  9 Connection to load controllers  17.12.2018 
 
Behavior in the event the building automation and control system fails 
 
If the LMV37.4 receives no more data from building automation, it will deliver the output 
set with 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 = deactivated 
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 (20 = low-fire position) 
 
For multistage operation, use the following settings: 
0 = burner OFF 
P1...P3 = stage 1...stage 3 
 
Invalid = no output predefined by the building automation system in the event 
of communication breakdown 
 
Default setting: Invalid 
 
Setting choices: 
a)  Set output specification in 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)  Output preset via parameter 148 set to 0, 20…100%, or parameterized as 
multistage: 
If communication breaks down, the output requested by the building automation 
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 
building automation system cannot be delivered.