Instructions

NetTEST II Menu Guide
12 © KUNBUS
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.