VEGA VEGASTAB 692 MD - Manual (Page 11)

VEGASTAB 692 MD 11
4 Setup
4.1 General information on HART ®
multidrop
As a rule, a HART ® sensor outputs a current
of 4...20 mA, proportional to the measured
value. Multidrop mode means that the sensor
always consumes a constant current of 4 mA.
The measured value is therefore no longer
transmitted by means of the strength of the
current, but exclusively through a digital
signal superimposed on the current. This
way, up to 15 HART
® sensors can be oper-
ated on one two-wire cable. However, before
connecting several sensors, each individual
sensor must be switched to multidrop mode
and have its own address (1-15) assigned
by VVO.
Keep in mind that the software VVO supports
the multidrop mode of HART
® sensors only in
version 2.60 and higher, and Visual VEGA
only in version 4.50 and higher.
Setup
4.2 Procedure
• Connect VEGASTAB 692 MD to power
supply.
• Connect VEGACONNECT 3 to VEGASTAB
692 MD and the serial interface of your PC.
• Connect the first HART ® sensor and adjust
to multidrop and instrument address 1 via
the software VVO (see chapter "4.3 Ad-
dress assignment with VVO").
• A HART ® load resistance must not be con-
nected as usual to the sensor cable, since
it is already integrated in VEGASTAB 692
MD
• Disconnect voltage from the first sensor
and mark address 1 outside on its hous-
ing.
• Connect the second sensor and set it to
multidrop with address 2 and mark it.
• Assign an address to all other sensors in
the same way and mark them.
• Connect all sensors to VEGASTAB 692 MD
and start the setup with VVO. Note that this
can last a few minutes depending on the
number of connected sensors.
• Check if all sensors are displayed in VVO.
• Carry out adjustment and parameter set-
ting of the individual sensors or measure-
ment loops.
• If all measurements work satisfactorily,
Visual VEGA can be installed for measured
value enquiry. If this is to be done by re-
mote enquiry via modem (previously con-
nected via a direct connection), the modem
connection cable for VEGACONNECT 3
(MODEM.KX) must be used. The con-
nected modem is then automatically initial-
ised with the correct interface parameters
by VEGACONNECT 3. The initialisation is
confirmed by the lighting of the AA-LED on
the modem.
Further information on modem operation
can be found in the operating instructions
manual Remote parameter adjustment
Remote parameter adjustment Remote parameter adjustment Remote parameter adjustment Remote parameter adjustment.