IDENT-I • IRI-KHD2-4HB5, IRI-KHA6-4HB5
Installation
Subject to reasonable modifications due to technical advances.
Copyright Fuchs, Printed in Germany
Fuchs Group • Tel.: Germany (06 21) 7 76-0 • USA (330) 4 25 35 55 • Singapore 7 79 90 91 • Internet http://www.pepperl-fuchs.com
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5.4.3
Special connection information for the INTERBUS cable
Ring closure switch
A key feature of the INTERBUS system is its physical ring structure. Each connected
unit lies in the bus between two other subscribers. If this is not the case, e.g. a bus
terminal at the end of a branch, the ring line in the affected unit must be closed.
This ring closure takes place automatically when the Sub-D connections are used.
If you use the screw terminals on the IRI-KHD2-4HB5/IRI-KHA6-4HB5 to connect the
bus line, you must move the rotary switch labelled "S1" for the ring closure to the
proper position (see figure 5.6). The ring closure switch is located on the top of the
unit.
Figure 5.6
Ring closure switch
If leads with double shielding are used, e.g. metallic wire mesh and
metallic foil, they must be connected to each other using a low imped-
ance connection at one end of the cable.
Many noise impulses come from the supply cables, e.g. switch-on cur-
rent of a motor. For this reason, running the supply cables in parallel
with the data/signal cables, especially in the same cable duct, should be
avoided.
The ring closure must only be activated at an open branch end! All sub-
sequent units will otherwise be cut off from communications.
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S1
