English 04/00 BT 200
(S)J31069-D0075-U001-A2-6318
Page 16
4.5 Reflection Test
The reflection test can be used to determine a
faulty location (e.g., short circuit) or to confirm
the distance measurement (not via repeater).
Reflections can occur, for example, in the fol-
lowing situations:
-
Stub lines exist.
-
Too many terminating resistors have be-
en inserted, or none have been inserted.
-
Change to a wrong type of cable occurs
within the measuring path.
Performing the test
Disconnect master from the bus, and make
sure that:
-
the bus termination has power
-
no bus communication occurs
-
no test plug connector is connected.
Connect BT 200 to one end of the line.
Start reflection measurement.
Test results
If no reflection (i.e., fault) is detected, the fol-
lowing message appears.
If a reflection is detected, the following mes-
sage appears.
The number in the display specifies the di-
stance in meters from the measuring point to
the faulty point.
If the distance of the reflection measurement
corresponds to a previous distance measu-
rement, this distance measurement is confir-
med. The wiring of the bus segment which
was measured is correct.