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HART multidrop mode
VEGATRENN 141 •
If the resistance of the connected processing system is less than
230 Ω, the digital adjustment signal is extremely damped or short-cir-
cuited. Digital communication with the PC is then no longer possible.
With low impedance processing systems, a resistor of approx. 230 Ω
must be looped into the 4 ... 20 mA cable. This resistor is already inte-
grated in VEGATRENN 141 and can be chosen through the selection
of the respective terminals.
No additional resistor is required in the sensor circuit for direct con-
nection of a HART-Master. When connecting a VEGADIS 82, the com-
munication resistor in the VEGADIS 82 must be deactivated.
In HART multidrop mode, the measured values are transmitted
on the same cable (bus) as the digital HART signals. An analogue
4 ... 20 mA transmission is not possible, the current is limited to 4 mA.
An own, unambiguous address (address range 1-15) must be as-
signed to each connected sensor. In this mode, up to five sensors can
be connected to one channel.
Information:
When using a HART resistor, keep in mind that there is an additional
voltage loss. You can find details in chapter " Technical data".
5.2
Connection procedure
The pluggable terminals can be removed as needed to allow more
convenient connection. To make the electrical connection, proceed as
follows:
1. Mount the instrument as described in the previous chapter
2. Connect sensor cable to terminal 1/2, and where applicable, con-
nect the shielding
3. Connect switched-off power supply to terminal 16/17
4. Connect processing circuit, e.g. from PLC to terminal 11/12 or
10/12 (with HART resistor), and shielding, if necessary
The electrical connection is finished.
Note:
If several sensors should be connected in HART multidrop mode, a
respective HART address must be assigned to each sensor before
connecting to VEGATRENN 141.
5 Connecting to power supply
11
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