Siemens SIMATIC NET PROFIBUS, Owner'S Manual

Page: 86 / 490

Configuring Networks
3-20
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
Power Budget for OLM G11-1300, G12-1300 for One Point-to-Point
Link at Wavelength
λ
= 1310 nm
Attenuation on the cable
Fiber type Attenuation
a
FOC
Cable length
L
62.5/125
µ
m 1.0 dB/km 9 km L* a
FOC
= 9.0 dB
+
Attenuation for connectors
a
Conn
Number +
1 dB 0 Number *
a
Conn
0 dB
Attenuation caused by splices +
a
Spl
Number
0.2 dB 5 Number * a
Spl
1.0 dB
Attenuation of the transmission path a
Path
= 10.0 dB
Data of the OLM/G11-1300, G12-1300 power that
can be coupled into 62.5/125
µ
m fibers
P
out, min
–17 dBm
Receiver sensitivity
Prec
, min
–29 dBm
Maximum permitted attenuation a
max
= P
out, min
– P
rec, min
= 12 dB
Link power margin a
max
– a
Path
= 2 dB
The transmission path can be implemented as planned.
Note
The maximum length of fiber-optic cable that can be supplied in one piece depends on the
cable type but is approximately 3 km per drum. Longer links must therefore be put together
using more than one piece of cable. To connect the sections of cable, coupling elements or
splices must be used reducing the maximum possible cable length due to their attenuation.