Siemens SIMATIC NET PROFIBUS Owner's Manual page 353

6ZB5530–3AC30–0BA1
5.2.1 Point–to–Point–Link
Slave
Master
PROFIBUS
master network segment
Master
Master
Figure 2: Point-to-Point Link with Two PROFIBUS ILMs
Figure 2 describes the typical layout of a PROFIBUS network with master and slave nodes and an infrared
transmission link with two PROFIBUS ILMs. The infrared transmission link is implemented as a point-to-point
link by the two PROFIBUS ILMs. In this situation, the two PROFIBUS ILMs replace a cable connection
between the two network segments. Remember that only slave nodes are permitted in the slave network
segments.
+
Make sure that the terminating resistors are activated at the segment ends (either in the bus
connector or in a PROFIBUS ILM).
Cascading is a further application for a point-to-point link.
Note
This "cascading with PROFIBUS ILM" mode is possible, but does involve a risk when operating PROFIBUS.
The transmission using an infrared link is generally more susceptible to problems than transmission via cable
(optical or electric).
Infrared
transmission link
0.5 to 15 m
ILM
PROFIBUS
slave network segment
11
Infrared Link Modul (ILM)
Slave
ILM
Slave
Slave
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