Siemens SIMATIC NET PG PROFIBUS Operating Instructions Manual page 24

Commissioning
5.2 Installation
Connecting the optical bus cables
Image 5-4
A = CH2, optical receiver
B = CH2, optical transmitter
C = CH3, optical receiver
D = CH3, optical transmitter
Connect the individual PROFIBUS OBTs using a duplex fiber-optic cable fitted with two pairs
of simplex connectors.
Make sure that an optical input is connected to an optical output (crossover connection).
Provide adequate strain relief for the fiber-optic cable and remember the minimum bend radii
of the FO cable.
Close unused FO cable sockets with the supplied plastic plugs. Incident light from the
surroundings can cause disturbances on the PROFIBUS network particularly, if the
surroundings are very bright.
Remember the minimum and maximum length of the FO cable and the permitted fiber types
listed in Table 1 and in the technical specifications.
Make sure that no dust gets into the optical components. Dust in the optical components can
make them unusable.
24
View of the module from the side with the optical channels CH2 and CH3
PROFIBUS Optical Bus Terminal (OBT)
Operating Instructions, 04/2016, C79000-G8976-C122-07