NetTEST II Menu Guide
12
©
COMSOFT
5.2.1.2 Test with no terminators
At the beginning of each test, the
Test with no term.
must be
carried out. For this, the
NetTEST II
must be connected to
one end of the PROFIBUS segment. Now the user makes sure
that all bus termination resistors (terminators) in the bus
segment are switched off resp. removed. Furthermore, no
Master may send data via the bus. Then the
Test with no term.
can be carried out. If, by accident, a bus terminator or Master
should be active in the segment, the
NetTEST II
recognizes
and indicates this at once. Only if no more resistance in the
thread is activated and all Masters are deactivated, the
NetTEST II
informs about:
•
Line impedance
•
Line length (segment length)
Detections in segments with PROFIBUS plugs with a
disconnection function can be tricky. If, e.g., in the
middle of a segment, the terminator of such a plug is
activated, the
NetTEST II
recognizes it, if it is measured
from the entrance side. However, if the measurement is
made from the other end of the plug, measuring is made
into the open end and a cable length, shorter than the one
expected, is indicated. Therefore please check very
thoroughly if all bus terminators are switched off.
Another possibility of finding such a plug is measuring
from the other side of the bus.
Содержание NetTEST II
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