Configuring Networks
3-15
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
Power Budget
The power budget of an optical link not only takes into account the attenuation in
the fiber itself, temperature and aging effects but also the attenuation values of the
connectors and splices and therefore provides exact information about whether or
not an optical link can be implemented. The starting point for calculating the
maximum transmission path length is the minimum transmitter power that can be
coupled into the fiber type. To simplify matters, the budget is calculated in dBm and
dB.
The following is subtracted from the minimum transmitter power:
S
The attenuation of the fiber a
FOC
[in dB/km or dB/m] (see manufacturers data)
S
The input power required at the receiver
The coupling losses at the send and receive diodes are already taken into account
in the information about the transmitter power and receiver sensitivity.
Plastic and PCF FO Cables
Plastic and PCF FO cables can only be used on short distances due to their
relatively high fiber attenuation. They are installed in one piece. Fiber-optic
connections with couplers or splices should not be considered since they further
reduce the distance that can be covered.
The maximum permitted cable lengths are listed in Tables 3-7 and 3-8.
Glass FO Cables
Glass FO cables can span distances in the kilometer range. It is often not possible
to install cables over such distances in one piece. The fiber-optic path must then
be put together in cable sections.
The couplers or splices where the sections are joined always involve certain
attenuation losses.
With transmission paths using glass fibers, the following aspects must also be
taken into account:
S
The attenuation of splices
S
The attenuation of connectors
S
When calculating the power budget, a link power margin of at least 3 dB (at a
wavelength of 860 nm) or at least 2 dB (at a wavelength of 1300 nm) must be
maintained.
Splices
Along with the splices, future repair splices must also be taken into account.
Depending on the route of the cables and the risk of mechanical damage, one or
more future repairs (approximately 1 per 500 m) should also be included in the
budget. A repair always means two splices since a new section of cable must be
inserted (the length depending on the accuracy of the test equipment).
Summary of Contents for SIMATIC NET PROFIBUS
Page 10: ...Contents viii PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 ...
Page 11: ...PROFIBUS NETWORKS 1 ...
Page 26: ...PROFIBUS NETWORKS 1 16 PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 ...
Page 241: ...A 1 PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 Testing PROFIBUS A ...
Page 254: ...Testing PROFIBUS A 14 PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 ...
Page 288: ...Installing LAN Cables C 26 PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 ...
Page 325: ...F 1 PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 Dimension Drawings F ...
Page 338: ...Dimension Drawings F 14 PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 ...
Page 396: ...Infrared Link Modul ILM 6ZB530 3AC30 0BA1 54 Copyright by Siemens ...
Page 434: ......
Page 438: ...Contents ii PROFIBUS Optical Bus Terminal OBT C79000 G8976 C122 02 Contents ...
Page 450: ...Network Topology 4 4 PROFIBUS Optical Bus Terminal OBT C79000 G8976 C122 02 ...
Page 458: ...Installation and Startup 5 8 PROFIBUS Optical Bus Terminal OBT C79000 G8976 C122 02 ...
Page 460: ...Troubleshooting 6 2 PROFIBUS Optical Bus Terminal OBT C79000 G8976 C122 02 ...
Page 464: ...Technical Specifications 7 4 PROFIBUS Optical Bus Terminal OBT C79000 G8976 C122 02 ...
Page 468: ...References 9 2 PROFIBUS Optical Bus Terminal OBT C79000 G8976 C122 02 ...
Page 470: ...Abbreviations 10 2 PROFIBUS Optical Bus Terminal OBT C79000 G8976 C122 02 ...
Page 478: ...References I 4 PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 ...
Page 488: ...Glossary Glossary 8 PROFIBUS Networks SIMATIC NET 6GK1970 5CA20 0AA1 Release 2 05 2000 ...