Beckhoff CU1521 Series - Application with CU1521 and CU1521-0010

Commissioning/application notes
CU1521-xxxx, CU1561 37Version: 2.5
5.2.3 Application with CU1521 and CU1521-0010
Application with CU1521 and CU1521-0010
The CU1521, CU1521-0010 are intended for application with optical fiber cables with the following
characteristics:
• SC duplex connector.
• CU1521: Duplex multimode 50/125 µm or 62.5/125 µm (inner/outer core diameter). The use of both
diameters is possible. However, the use of 50/125 µm is recommended due to the lower attenuation.
• CU1521-0010: Duplex single-mode 9/125 µm (inner/outer core diameter). A typically usable cable can
be manufactured according to the specification ITU-T G.652.D (0.4.4dBm/km at 1300nm).
Recommended connectors
The use of SC/PC connectors is recommended for connecting to the CU1521, CU1521-0010. The
advantage of the "PC" (physical contact) version of this connector is the crowned end face, which
allows the region of the fiber core that is relevant to transmission to be optimally joined when the
connector is pushed together. Other versions include, for instance, the SC/UPC (ultra-polish PC),
SC/HRL (high return loss) and the SC/APC plug (angled physical contact).
An additional feature of these connectors is that light that is reflected by the connector's end face,
which is at an angle of about 8° to the fiber axis, is refracted from the core by the cladding glass into
the air. This avoids interference with the data transmission, optimizing the core size of the back-
scatter.
50/125 µm or 62.5/125 µm
The use of both diameters is possible. However, the use of 50/125 µm is recommended due to the
lower attenuation.
In optical fibers the wavelengths 850 nm and 1300 nm are usually used for data transfer. Commercially
available optical fiber cables are usually optimized for application in one of these ranges, since signal
attenuation is frequency-dependent (like in copper cable), so that large ranges of several km can be
achieved for the respective wavelength. In general, optical fiber cables exhibit a lower attenuation at a
wavelength of 1300 nm than at 850 nm.
In the CU1521, CU1521-0010 a transceiver with the wavelength of 1300 nm is used.
Range and bandwidth product
Optical fiber cables are available in different qualities from reputable manufacturers. One of the
relevant parameters for the user is the frequency-dependent bandwidth product of a cable, specified
in [MHz*km]. The greater the bandwidth product, the lower the attenuation, and therefore the larger
the range that can be achieved with this cable (see ITU-T G-651). To maximize the range with the
CU1521, CU1521-0010 optical fiber cables with a maximum high bandwidth product at 1300 nm
should therefore be used. We recommend optical fiber cables from the OM2 class (EN50173:2002).
Standard optical fiber cables have a minimum bandwidth product of 500 MHz*km at 1300 nm,
higher-quality cables are suitable for distances > 500 m over > 1000 MHz*km.
For maximum distances the remote counterpart of the CU1521, CU1521-0010 should also support
such ranges.
Installation notes
The following parameters must be taken into account in the installation of optical fiber cables
• permitted bending radius
• permitted tensile strength
• sensitivity of the exposed contact ends
Further information can be found in the following documents:
• ITU recommendation ITU-T G.651 - G.655
• EN 50173:2002
• EN 60793-2