Commissioning/application notes
EK110x, EK15xx
56
Version: 3.6
5
Commissioning/application notes
5.1
Configuration overview
More detailed information on the configuration settings can be found in the
EtherCAT system documentation
on the Beckhoff website.
5.2
Application notes
5.2.1
Optical fiber application notes
Fig. 39:
EK1501
5.2.1.1
Notes on suitable optical fiber cables
General information on optical fiber types
Optical fiber are available as multimode and single mode types with different step and graded indices.
Step and graded index
Optical fiber cables consist of 2 concentric materials, the core and cladding, plus a protective (colored)
jacket. The core and the cladding have a different index of refraction, causing the light waves (modes; a
mode is a natural wave in the optical fiber) to be reflected back into the core at the boundary. Due to the step
change in the index of refraction this type of fiber is referred to as step index. A gradual/parabolic transition
between the index of refraction in the core and the coating (referred to as graded index) can be achieved by
mixing the materials. In a graded index fiber the modes are gradually diffracted back to the core, leading to
propagation-time compensation and significantly higher quality of the light pulse at the outlet compared with
a multimode step index fiber, where the different light modes have different signal run times (mode
dispersion) with associated front distortion.
