VRP10-O
PROFIBUS-PA OPTICAL REPEATER
INSTALLATION, OPERATION AND CONFIGURATION MANUAL
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1.3.
INSTALLATION
VRP10-O repeaters are easy to install and allow users to extend a PROFIBUS-PA segment up to 4 km
(2.5 mi). It can also be connected to different ground references, bringing an unprecedented advantage
once one of the major problems in digital network on the factory floor are just noise and current flowing
through the ground conductor due to ground differential between distant areas.
The figure below illustrates an application assembly between remote areas.
Occasionally, there might be adjustments in the PROFIBUS-DP master configuration, when
communication is not established successfully. The solution is setting TSL (time slot) and TTR (Token
Rotation Time). TSL is given in bit times and means the time PROFIBUS-DP master will wait for a slave
response before re-sending a frame or even send a new frame. TTR is given in bit times and is usually
calculated by the configuration tools. It is the time to pass the token across the network and return to its
original master. When working with multiple masters this includes the total time for each master to complete
its I/O cycle, pass the token to the next master and get token back to the original master. Some factors
directly influence the TTR: baud rate, number of slaves with cyclic data exchange, total number of I/O during
data exchange and quantity of masters.
It is possible to set several optical segments in cascade (a combination cable of PROFIBUS-PA + fiber
optics + PROFIBUS-PA cable). Eventually it might be necessary to adjust TSL and TTR parameters on
cyclic DP master configuration, as explained above. Figure below illustrates an application assembly
between remote areas.
Figure 1.3 - VRP10-O insulating control networks, allowing different ground references.
