Siemens SIMATIC NET PROFIBUS - Manual (Page 251)

Testing PROFIBUS
A-11
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
OTDR Evaluation
The OTDR provides the measurement results graphically
Distance
Start of fiber
Coupling
Fusion splice
Bonding splice
End of fiber
Backscatter
Power ]dB[
Figure A-5 Representation of the OTDR Measurement Results
Figure A-5 clearly illustrates that the power of the launched light reduces
constantly along the fiber-optic link. There are significant jumps at the coupling
points of the fiber.
The following conclusions can be drawn from these results:
S Whether the coupling points should be replaced due to excessive attenuation
S Whether the fiber has been damaged when installing the cable
S
The distance between the impairments and the start of the fiber
Based on this information,
S
defects resulting from installation can be eliminated,
S
fiber-optic links can be documented in detail and, if problems are occurring, can
be compared with the link at the time it was installed (warranty or not).