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5 Connecting to power supply
PLICSMOBILE • Mobile network unit PLICSMOBILE T81
55234-EN-191217
With this version, the PLICSMOBILE T81 and a 4 … 20 mA/HART
sensors are each powered via a separate power supply. Here, the
measured values can be transmitted via radio communication and
the 4 … 20 mA HART signal of the sensor is available in parallel for
processing, e.g. via a PLC.
5.3 HART communication
If the sensors are connected to PLICSMOBILE, HART communica-
tion is ensured and no additional HART resistor must be looped.
If the internal resistance of the connected power supply for the sensor
is less than 230 Ω, the HART signal is extremely damped or short-
circuited. Digital communication with PLICSCOM is then no longer
possible. With low impedance processing systems, a resistance of
approx. 230 Ω must be looped into the 4 … 20 mA/HART cable. This
resistance is already integrated in PLICSMOBILE T81 and can be
looped automatically into the circuit by selecting the appropriate wires
(see wiring plans with or without HART resistor).
The connection to power supply is carried out as described in the
respective operating instructions manual.
Note:
When connecting more than one HART sensor, a different address
must be assigned to each sensor (address range 1-15). Address 0
(mode 4 … 20 mA) may not be used. When assigning an address,
only one sensor should be connected to PLICSMOBILE T81. If con-
nection is already completed, the wiring must be briefly undone for
addressing. Depending on the installation location of the sensors, it
can be advantageous to carry out this addressing before installing
and connecting the sensors. This can be conveniently carried out
e.g. in the workshop. You only need a 24 Volt power supply as well as
an indicating and adjustment module PLICSCOM or the adjustment
software PACTware with VEGACONNECT.
The HART protocol enables the connection of up to two masters on
the same line (Primary/Secondary Master). The PLICSMOBILE T81
works as Primary Master in the factory setting. If another master is to
be connected, e.g. for parameterization of the sensor, it must work as
a Secondary Master. If this is not possible, the PLICSMOBILE T81
can alternatively be reconfigured as a Secondary Master.
5.4 Connection steps sensor connection cable
The sensor connection cable is used for transmission of the meas-
ured value from the sensors to the PLICSMOBILE T81. In addition, it
can also transmit the voltage supply for all connected sensors.
The sensor connection cable is available in Ex version (blue)
as well as in non-Ex version (black). It can be ordered in three
lengths (5/10/25 m) and can be shortened afterwards to individual
lengths. On one end there is a ready-for-use plug for connection to
PLICSMOBILE T81. On the other end are free cable ends for direct
connection to the sensor.
Separate voltage sup-
ply for sensor and
PLICSMOBILE
HART resistor with com-
mon power supply
HART resistor with sepa-
rate power supply
HART address
HART master mode
