Application With Ek1521 And Ek1521-0010 - Beckhoff EtherCAT EK112 Series Manual

3.3.4

Application with EK1521 and EK1521-0010

Application with EK1521 and EK1521-0010
The EK1521, EK1521-0010 is intended for application with optical fiber cables with the following
characteristics:
• SC duplex connector
• EK1521: 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.
• EK1521-0010: 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 dBm/km at 1300 nm).
Recommended connectors
The use of SC/PC connectors is recommended for connecting to the EK1521, EK1521-0010. 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 fiber-optic 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. Fiber-optic cables in the 1300 nm window generally have lower
attenuation than cables in the 850 nm window.
In the EK1521, EK1521-0010 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). For achieving the maximum
range with the EK1521, EK1521-0010, optical fibers with a maximum bandwidth product of 1300 nm
should therefore be used; we recommended using class OM2 optical fibers (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. In order to achieve
the maximum range, the device to which the EK1521, EK1521-0010 is connected must also support
such ranges.
Installation notes
• 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
EK112x, EK15xx Version: 3.6
Commissioning/application notes
45