Dimensioning of a fieldbus segment, Fieldbarrier – VEGA FIELDBARRIER User Manual
Page 26
FieldBarrier
Subject to reasonable modifications due to technical advances.
Copyright Pepperl+Fuchs, Printed in Germany
Pepperl+Fuchs Group • Tel.: Germany +49-621-776-0 • USA +1-330-4253555 • Singapore +65-67-799091 • Internet www.pepperl-fuchs.com
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• By possibility 1, the trunk is directed into the FieldBarrier through one of the EEx e
cable glands and back out through the second EEx e cable gland.
• By possibility 2, the FieldBarrier is connected to the trunk via a junction box Care
must be taken here that the connection line between the junction box and FieldBar-
rier is < 1 m.
The transmitters integrated into the FieldBarrier are used to transfer impedances con-
nected to the outputs to the trunk.
6.3
Dimensioning of a fieldbus segment
Dimensioning of a fieldbus segment is described in the
• Instruction manual/manual segment coupler.
• Instruction manual/manual Fieldbus components.
However, the calculation of maximum permissible line length described there is only
valid if each fieldbus station of a segment has a linear characteristic input curve.
To simplify dimensioning of a fieldbus segment, Pepperl+Fuchs has
developed the software tool "segmentchecker" that makes the necessary calcula-
tions. You can download this tool from the home page www.segmentchecker.com.
6.4
Terminating the trunk with a fieldbus terminating resistor.
The transmission line of a fieldbus application must be equipped with a fieldbus ter-
minator. The fieldbus resistor must be mounted in such a manner as to ensure the
longest possible line length between the segment coupler/power repeater/power con-
ditioner and the fieldbus terminating resistor.
The P+F FieldBarrier Segment Checker for FOUNDATION Fieldbus software pro-
gram shows where the fieldbus terminating resistor should be wired in.
From the point of view of the trunk, each wired output of a FieldBarrier
represents a spur.
The FieldBarrier has a non-linear characteristic input curve.
An external terminating resistor can also be used.