Siemens SIMATIC NET PROFIBUS - Manual (Page 391)

Infrared Link Modul (ILM) 6ZB5530–3AC30–0BA1
49 Copyright
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by Siemens
11.1 Illumination Range
To determine the arrangement of two PROFIBUS ILMs on an infrared transmission link, the illumination range
of the sending PROFIBUS ILM must be known. The receive cone is broader so that with the half-duplex
transmission used with PROFIBUS the restriction results from the narrower cone.
Note
Each PROFIBUS ILM on an infrared link must be arranged and aligned so that it reaches its partner with its
transmit cone.
The illumination range of the sender is shown in Figure 19. In the range from 0.5 to 12 m, there is adequate
illumination density in a solid angle of
)
/– 10 degrees with free emission without shadows caused by
obstacles. At 12 m distance from the sending PROFIBUS ILM, there is an illuminated circular area with a
diameter of approximately 4 m. Although the send window of the PROFIBUS ILM is neither round nor square,
from a distance of 2 m the illuminated area is practically round since from this distance the light source can be
assumed to be a point.
At a distance greater than 12 m, in the same way as the illumination provided by a spotlight, the illuminated
area starts to reduce. At 15 m distance, an illuminated area of 2 m diameter is guaranteed.
Note
These data are only guaranteed when the windows of the PROFIBUS ILM are clean. From time to time, the
window should be cleaned using a clean soft cloth as usual with other optical devices or glasses. Under no
circumstances should aggressive or abrasive cleaning agents be used.
Condensation on the window or wetting with water or other liquids reduces the illumination range. With
condensation, a reduction of approximately half of the maximum range has been measured. If the liquid
produces bubbles, the reduction is sometimes even higher since not only the optical attenuation but also the
optical refraction of the liquid takes effect.