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Building Technologies User Manual OCI600 74 319 0002 0 c
HVAC Products Remedy in the event of problems with the LPB 15.07.2005
6 Remedy in the event of
problems with the LPB
6.1 General note
To ensure correct engineering of buses and to facilitate the
successful solution of problems in connection with the LPB, a
number of parameters such as cross-sectional area of the
cable, total cable length, distances to the next power source,
and distances between 2 LPB partners must be taken into
consideration. This complex subject cannot be fully covered
in the present document.
If you require additional information on engineering, or if you
encounter major problems in connection with this subject,
please contact your Siemens Service.
6.2 Selected phenomena and
proposals for remedy
After a bus settling time of 3 seconds, there is no power on
the bus.
Possible causes:
• There is no central bus power supply, or it is incorrectly
connected
• The central bus power supply is defective
• There is a short-circuit on the bus line between bus
power supply and measuring point
• The bus line is interrupted
Remedy:
Test the bus line for continuity and check the connection.
The bus voltage (bus level) throughout the network is below
9.5 V (make measurement when there is no communication
on the bus).
Possible causes:
• The bus power supply is not sufficient
Note
No bus voltage
Voltage too low
throughout the
network
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