Shield Connection; Bus Termination - Drehmo c-matic Operating Manual

- The shielding of the PROFIBUS cable has to be tightened securely by means of the
respective cable clamps
- The cable glands have to be fastened with the prescribed torque value in order to
guarantee the specified IP grade.
For the crimping of the ferrules we recommend the usage of the crimping tool from company
WAGO - Variocrimp 4. Uniform, compact crimping on all four sides for high conductor retention is
best suited for the used terminals.

3.4 Shield connection

The strain relief clamps for the PROFIBUS cable and the A/D input cable may be used for the
cable shielding – instead of the preferred usage of EMC cable glands. The strain relief clamps are
electrical connected via a RC combination to the housing. By means of this, highly frequent
signals can be deflected to the housing. Current flow over the shielding due to stray electric
currents in the overall plant installation can be avoided. In case of a good potential equalization
between the connected field devices, the RC combinations can be short-circuit via the according
switches in order to have an optimized conduction of possible disturbance signals from the cable
shield to the housing.

3.5 Bus termination

RS485 segments have to be terminated and conditioned at the beginning and the end in order to
define the signal levels and avoid signal reflections. On the appropriate actuators, the termination
switch S1 for BUS1 and S2 for BUS2 has to be in position „TERM" (termination active). If the
termination is active, the outgoing PROFIBUS signal is decoupled from the incoming signal. By
means of this, subsequent field devices are disconnected from the master. If subsequent field
devices are existing, the termination switch S1 resp. S2 have to be in the position „IN=OUT"
(termination inactive).
Active conditioning of the fieldbus signals in case of activated termination is only given, if
the actuator electronic is powered via the mains power connection or the optional
existing external 24V DC supply.
DREHMO - MaticC Profibus DPV0/DPV1
Complementary operating manual
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